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<front>
<title abbrev="RTP payload format for VVC">RTP Payload Format for Versatile <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" submissionType
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<front>
<title abbrev="RTP Payload Format for VVC">RTP Payload Format for Versatile
Video Coding (VVC)</title>
<seriesInfo name="RFC" value="9328"/>
<author initials="S." surname="Zhao" fullname="Shuai Zhao"> <author initials="S." surname="Zhao" fullname="Shuai Zhao">
<organization>Intel</organization> <organization>Intel</organization>
<address> <address>
<postal> <postal>
<street>2200 Mission College Blvd</street> <street>2200 Mission College Blvd</street>
<city>Santa Clara</city> <city>Santa Clara</city>
<code>95054</code> <code>95054</code>
<country>USA</country> <country>United States of America</country>
</postal> </postal>
<email>shuai.zhao@ieee.org</email> <email>shuai.zhao@ieee.org</email>
</address> </address>
</author> </author>
<author initials="S." surname="Wenger" fullname="Stephan Wenger"> <author initials="S." surname="Wenger" fullname="Stephan Wenger">
<organization>Tencent</organization> <organization>Tencent</organization>
<address> <address>
<postal> <postal>
<street>2747 Park Blvd</street> <street>2747 Park Blvd</street>
<city>Palo Alto</city> <city>Palo Alto</city>
<code>94588</code> <code>94588</code>
<country>USA</country> <country>United States of America</country>
</postal> </postal>
<email>stewe@stewe.org</email> <email>stewe@stewe.org</email>
</address> </address>
</author> </author>
<author initials="Y." surname="Sanchez" fullname="Yago Sanchez"> <author initials="Y." surname="Sanchez" fullname="Yago Sanchez">
<organization>Fraunhofer HHI</organization> <organization>Fraunhofer HHI</organization>
<address> <address>
<postal> <postal>
<street>Einsteinufer 37</street> <street>Einsteinufer 37</street>
<city>Berlin</city> <city>Berlin</city>
skipping to change at line 60 skipping to change at line 60
<email>yago.sanchez@hhi.fraunhofer.de</email> <email>yago.sanchez@hhi.fraunhofer.de</email>
</address> </address>
</author> </author>
<author initials="Y.-K." surname="Wang" fullname="Ye-Kui Wang"> <author initials="Y.-K." surname="Wang" fullname="Ye-Kui Wang">
<organization>Bytedance Inc.</organization> <organization>Bytedance Inc.</organization>
<address> <address>
<postal> <postal>
<street>8910 University Center Lane</street> <street>8910 University Center Lane</street>
<city>San Diego</city> <city>San Diego</city>
<code>92122</code> <code>92122</code>
<country>USA</country> <country>United States of America</country>
</postal> </postal>
<email>yekui.wang@bytedance.com</email> <email>yekui.wang@bytedance.com</email>
</address> </address>
</author> </author>
<author initials="M." surname="&nbsp;M Hannuksela" fullname="Miska M. Hannuk sela"> <author initials="M." surname=" M Hannuksela" fullname="Miska M. Hannuksela" >
<organization>Nokia Technologies</organization> <organization>Nokia Technologies</organization>
<address> <address>
<postal> <postal>
<street>Hatanpään valtatie 30</street> <street>Hatanpään valtatie 30</street>
<city>Tampere</city> <city>Tampere</city>
<code>33100</code> <code>33100</code>
<country>Finland</country> <country>Finland</country>
</postal> </postal>
<email>miska.hannuksela@nokia.com</email> <email>miska.hannuksela@nokia.com</email>
</address> </address>
</author> </author>
<date year="2022" month="December"/>
<date year="2022" month="August" day="01"/> <area>art</area>
<area>ART</area>
<workgroup>avtcore</workgroup> <workgroup>avtcore</workgroup>
<keyword>Internet-Draft</keyword> <keyword>H.266</keyword>
<keyword>ISO/IEC 23090-3</keyword>
<keyword>MPEG-I Part 3</keyword>
<keyword>RTP Payload</keyword>
<keyword>Video</keyword>
<abstract> <abstract>
<t> This memo describes an RTP payload format for the Versatile Video Cod
<t>This memo describes an RTP payload format for the video coding ing (VVC)
standard ITU-T Recommendation H.266 and ISO/IEC International specification, which was published as both ITU-T Recommendation H.266 and ISO/
Standard 23090-3, both also known as Versatile Video Coding (VVC) and IEC
developed by the Joint Video Experts Team (JVET). The RTP payload International Standard 23090-3. VVC was developed by the Joint Video Experts
Team (JVET). The RTP payload
format allows for packetization of one or more Network Abstraction format allows for packetization of one or more Network Abstraction
Layer (NAL) units in each RTP packet payload as well as fragmentation Layer (NAL) units in each RTP packet payload, as well as fragmentation
of a NAL unit into multiple RTP packets. The payload format has wide of a NAL unit into multiple RTP packets. The payload format has wide
applicability in videoconferencing, Internet video streaming, and applicability in videoconferencing, Internet video streaming, and
high-bitrate entertainment-quality video, among other applications.</t> high-bitrate entertainment-quality video, among other applications.</t>
</abstract> </abstract>
</front> </front>
<middle> <middle>
<section anchor="introduction">
<section anchor="introduction"><name>Introduction</name> <name>Introduction</name>
<t>The Versatile Video Coding specification was formally published as both
<t>The Versatile Video Coding specification was formally published as both ITU-T ITU-T Recommendation H.266 <xref target="VVC"/> and ISO/IEC International Stand
Recommendation H.266 <xref target="VVC"/> and ISO/IEC International Standard 23 ard 23090-3 <xref target="ISO23090-3"/>. VVC is reported to provide significant
090-3 <xref target="ISO23090-3"/>. VVC is reported to provide significant codin coding efficiency gains over High Efficiency Video Coding <xref target="HEVC"/>
g efficiency gains over High Efficiency Video Coding <xref target="HEVC"/>, also , also known as H.265, and other earlier video codecs.</t>
known as H.265, and other earlier video codecs.</t> <t>This memo specifies an RTP payload format for VVC. It shares its
basic design with the NAL-unit-based RTP
<t>This memo specifies an RTP payload format for VVC. It shares its payload formats of Advanced Video Coding (AVC) <xref target="RFC6184"/>, Scalabl
basic design with the NAL (Network Abstraction Layer) unit based RTP e Video Coding
payload formats of AVC Video Coding <xref target="RFC6184"/>, Scalable Video Cod (SVC) <xref target="RFC6190"/>, and High Efficiency Video Coding (HEVC) <xref ta
ing rget="RFC7798"/>, as well as
(SVC) <xref target="RFC6190"/>, High Efficiency Video Coding (HEVC) <xref target
="RFC7798"/> and
their respective predecessors. With respect to design their respective predecessors. With respect to design
philosophy, security, congestion control, and overall implementation philosophy, security, congestion control, and overall implementation
complexity, it has similar properties to those earlier payload format complexity, it has similar properties to those earlier payload format
specifications. This is a conscious choice, as at least RFC 6184 is specifications. This is a conscious choice, as at least <xref target="RFC6184"/ > is
widely deployed and generally known in the relevant implementer widely deployed and generally known in the relevant implementer
communities. Certain scalability-related mechanisms known from <xref target="RF C6190"/> were incorporated into this document, as VVC version 1 supports tempora l, spatial, and communities. Certain scalability-related mechanisms known from <xref target="RF C6190"/> were incorporated into this document, as VVC version 1 supports tempora l, spatial, and
signal-to-noise ratio (SNR) scalability.</t> signal-to-noise ratio (SNR) scalability.</t>
<section anchor="overview-of-the-vvc-codec">
<section anchor="overview-of-the-vvc-codec"><name>Overview of the VVC Codec</nam <name>Overview of the VVC Codec</name>
e> <t>VVC and HEVC share a similar hybrid video codec design. In this
<t>VVC and HEVC share a similar hybrid video codec design. In this
memo, we provide a very brief overview of those features of VVC memo, we provide a very brief overview of those features of VVC
that are, in some form, addressed by the payload format specified that are, in some form, addressed by the payload format specified
herein. Implementers have to read, understand, and apply the ITU-T/ISO/IEC spec ifications pertaining to VVC to arrive at herein. Implementers have to read, understand, and apply the ITU-T/ISO/IEC spec ifications pertaining to VVC to arrive at
interoperable, well-performing implementations.</t> interoperable, well-performing implementations.</t>
<t>Conceptually, both VVC and HEVC include a Video Coding Layer (VCL),
<t>Conceptually, both VVC and HEVC include a Video Coding Layer (VCL),
which is often used to refer to the coding-tool features, and a NAL, which which is often used to refer to the coding-tool features, and a NAL, which
is often used to refer to the systems and transport interface aspects of the cod ecs.</t> is often used to refer to the systems and transport interface aspects of the cod ecs.</t>
<section anchor="coding-tool-features-informative">
<section anchor="coding-tool-features-informative"><name>Coding-Tool Features (i <name>Coding-Tool Features (Informative)</name>
nformative)</name> <t>Coding-tool features are described below with occasional reference
to
<t>Coding tool features are described below with occasional reference to the coding-tool set of HEVC, which is well known in the community.</t>
the coding tool set of HEVC, which is well known in the community.</t> <t>Similar to earlier hybrid-video-coding-based standards, including
<t>Similar to earlier hybrid-video-coding-based standards, including
HEVC, the following basic video coding design is employed by VVC. HEVC, the following basic video coding design is employed by VVC.
A prediction signal is first formed by either intra- or motion- A prediction signal is first formed by either intra- or motion-
compensated prediction, and the residual (the difference between the compensated prediction, and the residual (the difference between the
original and the prediction) is then coded. The gains in coding original and the prediction) is then coded. The gains in coding
efficiency are achieved by redesigning and improving almost all parts efficiency are achieved by redesigning and improving almost all parts
of the codec over earlier designs. In addition, VVC includes several of the codec over earlier designs. In addition, VVC includes several
tools to make the implementation on parallel architectures easier.</t> tools to make the implementation on parallel architectures easier.</t>
<t>Finally, VVC includes temporal, spatial, and SNR scalability, as we
<t>Finally, VVC includes temporal, spatial, and SNR scalability as well ll
as multiview coding support.</t> as multiview coding support.</t>
<dl newline="true" spacing="normal">
<t>Coding blocks and transform structure</t> <dt>Coding blocks and transform structure</dt>
<dd>Among major coding-tool differences between HEVC and VVC, one of
<t>Among major coding-tool differences between HEVC and VVC, one of
the important improvements is the more flexible coding tree structure the important improvements is the more flexible coding tree structure
in VVC, i.e., multi-type tree. In addition to quadtree, binary and in VVC, i.e., multi-type tree. In addition to quadtree, binary and
ternary trees are also supported, which contributes significant ternary trees are also supported, which contributes significant
improvement in coding efficiency. Moreover, the maximum size of a improvement in coding efficiency. Moreover, the maximum size of a
coding tree unit (CTU) is increased from 64x64 to 128x128. To coding tree unit (CTU) is increased from 64x64 to 128x128. To
improve the coding efficiency of chroma signal, luma chroma separated improve the coding efficiency of chroma signal, luma-chroma-separated
trees at CTU level may be employed for intra-slices. The square transforms trees at CTU level may be employed for intra slices. The square transforms
in HEVC are extended to non-square transforms for rectangular blocks in HEVC are extended to non-square transforms for rectangular blocks
resulting from binary and ternary tree splits. Besides, VVC supports resulting from binary and ternary tree splits. Besides, VVC supports
multiple transform sets (MTS), including DCT-2, DST-7, and DCT-8 as well multiple transform sets (MTSs), including DCT-2, DST-7, and DCT-8, as well
as the non-separable secondary transform. The transforms used in VVC as the non-separable secondary transform. The transforms used in VVC
can have different sizes with support for larger transform sizes. For DCT-2, can have different sizes with support for larger transform sizes. For DCT-2,
the transform sizes range from 2x2 to 64x64, and for DST-7 and DCT-8, the the transform sizes range from 2x2 to 64x64, and for DST-7 and DCT-8, the
transform sizes range from 4x4 to 32x32. In addition, VVC also transform sizes range from 4x4 to 32x32. In addition, VVC also
support sub-block transform for both intra and inter coded blocks. support sub-block transform for both intra- and inter-coded blocks.
For intra coded blocks, intra sub-partitioning (ISP) may be used to For intra-coded blocks, intra sub-partitioning (ISP) may be used to
allow sub-block based intra prediction and transform. For inter allow sub-block-based intra prediction and transform. For inter blocks, sub-blo
blocks, sub-block transform may be used assuming that only a part of ck transform may be used assuming that only a part of
an inter-block has non-zero transform coefficients.</t> an inter block has non-zero transform coefficients.</dd>
<dt>Entropy coding</dt>
<t>Entropy coding</t> <dd>Similar to HEVC, VVC uses a single entropy-coding engine, which is
based on context adaptive binary arithmetic coding <xref target="CABAC"/>
<t>Similar to HEVC, VVC uses a single entropy-coding engine, which is
based on context adaptive binary arithmetic coding <xref target="CABAC"/>,
but with the support of multi-window sizes. The window sizes can be but with the support of multi-window sizes. The window sizes can be
initialized differently for different context models. Due to such a initialized differently for different context models. Due to such a
design, it has more efficient adaptation speed and better coding design, it has more efficient adaptation speed and better coding
efficiency. A joint chroma residual coding scheme is applied to efficiency. A joint chroma residual coding scheme is applied to
further exploit the correlation between the residuals of two color further exploit the correlation between the residuals of two color
components. In VVC, different residual coding schemes are applied components. In VVC, different residual coding schemes are applied
for regular transform coefficients and residual samples generated for regular transform coefficients and residual samples generated
using transform-skip mode.</t> using transform-skip mode.</dd>
<dt>In-loop filtering</dt>
<t>In-loop filtering</t> <dd>VVC has more feature support in loop filters than HEVC. The
<t>VVC has more feature support in loop filters than HEVC. The
deblocking filter in VVC is similar to HEVC but operates at a deblocking filter in VVC is similar to HEVC but operates at a
smaller grid. After deblocking and sample adaptive offset (SAO), an smaller grid. After deblocking and sample adaptive offset (SAO), an
adaptive loop filter (ALF) may be used. As a Wiener filter, ALF adaptive loop filter (ALF) may be used. As a Wiener filter, ALF
reduces distortion of decoded pictures. Besides, VVC introduces a reduces distortion of decoded pictures. Besides, VVC introduces a
new module called luma mapping with chroma scaling new module called luma mapping with chroma scaling
to fully utilize the dynamic range of signal so that rate-distortion to fully utilize the dynamic range of signal so that rate-distortion
performance of both Standard Dynamic Range (SDR) and High Dynamic Range (HDR) co performance of both Standard Dynamic Range (SDR) and High Dynamic Range (HDR) co
ntent is improved.</t> ntent is improved.</dd>
<dt>Motion prediction and coding</dt>
<t>Motion prediction and coding</t> <dd>Compared to HEVC, VVC introduces several improvements in this area
.
<t>Compared to HEVC, VVC introduces several improvements in this area.
First, there is the adaptive motion vector resolution (AMVR), which First, there is the adaptive motion vector resolution (AMVR), which
can save bit cost for motion vectors by adaptively signaling motion can save bit cost for motion vectors by adaptively signaling motion
vector resolution. Then the affine motion compensation is included vector resolution. Then, the affine motion compensation is included
to capture complicated motion like zooming and rotation. Meanwhile, to capture complicated motion-like zooming and rotation. Meanwhile,
prediction refinement with the optical flow with affine mode (PROF) prediction refinement with the optical flow (PROF) with affine mode
is further deployed to mimic affine motion at the pixel level. is further deployed to mimic affine motion at the pixel level.
Thirdly the decoder side motion vector refinement (DMVR) is a method Thirdly, the decoder-side motion vector refinement (DMVR) is a method
to derive MV vector at decoder side based on block matching so that fewer bits m to derive the motion vector at the decoder side based on block matching so that
ay be spent fewer bits may be spent
on motion vectors. Bi-directional optical flow (BDOF) is a similar on motion vectors. Bidirectional optical flow (BDOF) is a similar
method to PROF. BDOF adds a sample wise offset at 4x4 sub-block level that is d method to PROF. BDOF adds a sample-wise offset at the 4x4 sub-block level that
erived with equations based on gradients of the prediction samples and a motion is derived with equations based on gradients of the prediction samples and a mot
difference relative to CU motion vectors. Furthermore, merge with motion vector ion difference relative to coding-unit (CU) motion vectors. Furthermore, merge
difference (MMVD) with motion vector difference (MMVD)
is a special mode, which further signals a limited set of motion is a special mode that further signals a limited set of motion
vector differences on top of merge mode. In addition to MMVD, there vector differences on top of merge mode. In addition to MMVD, there
are another three types of special merge modes, i.e., sub-block are another three types of special merge modes, i.e., sub-block
merge, triangle, and combined intra-/inter-prediction (CIIP). Sub-block merge l ist includes one candidate of sub-block temporal motion merge, triangle, and combined intra/inter prediction (CIIP). The sub-block merg e list includes one candidate of sub-block temporal motion
vector prediction (SbTMVP) and up to four candidates of affine motion vector prediction (SbTMVP) and up to four candidates of affine motion
vectors. Triangle is based on triangular block motion compensation. vectors. Triangle is based on triangular block motion compensation.
CIIP combines intra- and inter- predictions with weighting. CIIP combines intra and inter predictions with weighting.
Adaptive weighting may be employed with a block-level tool called Adaptive weighting may be employed with a block-level tool called
bi-prediction with CU based weighting (BCW) which provides more bi-prediction with CU-based weighting (BCW), which provides more
flexibility than in HEVC.</t> flexibility than in HEVC.</dd>
<dt>Intra prediction and intra coding</dt>
<t>Intra prediction and intra-coding</t> <dd>To capture the diversified local image texture directions with fin
er
<t>To capture the diversified local image texture directions with finer
granularity, VVC supports 65 angular directions instead of 33 granularity, VVC supports 65 angular directions instead of 33
directions in HEVC. The intra mode coding is based on a 6-most-probable-mode sc heme, and the 6 most probable modes are derived using directions in HEVC. The intra mode coding is based on a 6-most-probable-modes s cheme, and the 6 most probable modes are derived using
the neighboring intra prediction directions. In addition, to deal the neighboring intra prediction directions. In addition, to deal
with the different distributions of intra prediction angles for with the different distributions of intra prediction angles for
different block aspect ratios, a wide-angle intra prediction (WAIP) different block aspect ratios, a wide-angle-intra-prediction (WAIP)
scheme is applied in VVC by including intra prediction angles scheme is applied in VVC by including intra prediction angles
beyond those present in HEVC. Unlike HEVC which only allows using beyond those present in HEVC. Unlike HEVC, which only allows using
the most adjacent line of reference samples for intra prediction, the most adjacent line of reference samples for intra prediction,
VVC also allows using two further reference lines, as known as VVC also allows using two further reference lines, known as
multi-reference-line (MRL) intra prediction. The additional multi-reference-line (MRL) intra prediction. The additional
reference lines can be only used for the 6 most probable intra prediction reference lines can be only used for the 6 most probable intra prediction
modes. To capture the strong correlation between different colour modes. To capture the strong correlation between different color
components, in VVC, a cross-component linear mode (CCLM) is components, in VVC, a cross-component linear mode (CCLM) is
utilized which assumes a linear relationship between the luma sample values and their associated chroma samples. For intra prediction, utilized, which assumes a linear relationship between the luma sample values and their associated chroma samples. For intra prediction,
VVC also applies a position-dependent prediction combination (PDPC) VVC also applies a position-dependent prediction combination (PDPC)
for refining the prediction samples closer to the intra prediction for refining the prediction samples closer to the intra prediction
block boundary. Matrix-based intra prediction (MIP) modes are also block boundary. Matrix-based intra prediction (MIP) modes are also
used in VVC which generates an up to 8x8 intra prediction block used in VVC, which generates an up to 8x8 intra prediction block
using a weighted sum of downsampled neighboring reference samples, using a weighted sum of downsampled neighboring reference samples,
and the weights are hardcoded constants.</t> and the weights are hard-coded constants.</dd>
<dt>Other coding-tool features</dt>
<t>Other coding-tool features</t> <dd>VVC introduces dependent quantization (DQ) to reduce quantization
error by state-based switching between two quantizers.</dd>
<t>VVC introduces dependent quantization (DQ) to reduce quantization </dl>
error by state-based switching between two quantizers.</t> </section>
<section anchor="systems-and-transport-interfaces-informative">
</section> <name>Systems and Transport Interfaces (Informative)</name>
<section anchor="systems-and-transport-interfaces-informative"><name>Systems and <t>VVC inherits the basic systems and transport interface designs
Transport Interfaces (informative)</name>
<t>VVC inherits the basic systems and transport interfaces designs
from HEVC and AVC. These include the NAL-unit-based syntax from HEVC and AVC. These include the NAL-unit-based syntax
structure, the hierarchical syntax and data unit structure, the structure, the hierarchical syntax and data unit structure, the
supplemental enhancement information (SEI) message mechanism, and the supplemental enhancement information (SEI) message mechanism, and the
video buffering model based on the hypothetical reference decoder video buffering model based on the hypothetical reference decoder
(HRD). The scalability features of VVC are conceptually similar to (HRD). The scalability features of VVC are conceptually similar to
the scalable variant of HEVC known as SHVC. The hierarchical syntax the scalable extension of HEVC, known as SHVC. The hierarchical syntax
and data unit structure consists of parameter sets at various levels and data unit structure consists of parameter sets at various levels
(decoder, sequence (pertaining to all), sequence (pertaining to a single), (i.e., decoder, sequence (pertaining to all), sequence (pertaining to a single), and
picture), picture-level header parameters, slice-level header parameters, and lo wer-level parameters.</t> picture), picture-level header parameters, slice-level header parameters, and lo wer-level parameters.</t>
<t>A number of key components that influenced the network abstraction
<t>A number of key components that influenced the network abstraction layer design of VVC, as well as this memo, are described below</t>
layer design of VVC as well as this memo are described below</t> <dl newline="true" spacing="normal">
<dt>Decoding capability information</dt>
<t>Decoding capability information</t> <dd>The decoding capability information (DCI) includes parameters that
stay constant for the lifetime of a VVC bitstream in the duration of a video co
<t>The decoding capability information includes parameters that stay constant fo nference, continuous video stream, and similar, i.e., any video that is processe
r the lifetime of a VVC bitstream in the duration of a video conference, continu d by a decoder between setup and teardown. For streaming, the requirement of co
ous video stream, and similar—any video that is processed by a decoder between s nstant parameters pertains through splicing. Such information includes profile,
etup and teardown. For streaming, the requirement of constant parameters pertai level, and sub-profile information to determine a maximum capability interop poi
ns through splicing. Such information includes profile, level, and sub-profile i nt that is guaranteed to never be exceeded, even if splicing of video sequences
nformation to determine a maximum capability interop point that is guaranteed to occurs within a session. It further includes constraint fields (most of which ar
be never exceeded, even if splicing of video sequences occurs within a session. e flags), which can optionally be set to indicate that the video bitstream will
It further includes constraint fields (most of which are flags), which can opti be constrained in the use of certain features, as indicated by the values of tho
onally be set to indicate that the video bitstream will be constrained in the us se fields. With this, a bitstream can be labeled as not using certain tools, whi
e of certain features as indicated by the values of those fields. With this, a b ch allows, among other things, for resource allocation in a decoder implementati
itstream can be labeled as not using certain tools, which allows among other thi on.</dd>
ngs for resource allocation in a decoder implementation.</t> <dt>Video parameter set</dt>
<dd>The video parameter set (VPS) pertains to one or more coded video
<t>Video parameter set</t> sequences (CVSs) of multiple layers covering the same range of access units and
includes, among other information, decoding dependency expressed as information
<t>The video parameter set (VPS) pertains to one or more coded video sequences ( for reference-picture-list construction of enhancement layers. The VPS provides
CVSs) of multiple layers covering the same range of access units, and includes, a "big picture" of a scalable sequence, including what types of operation points
among other information, decoding dependency expressed as information for refere are provided; the profile, tier, and level of the operation points; and some ot
nce picture list construction of enhancement layers. The VPS provides a "big pic her high-level properties of the bitstream that can be used as the basis for ses
ture" of a scalable sequence, including what types of operation points are provi sion negotiation and content selection, etc. One VPS may be referenced by one or
ded, the profile, tier, and level of the operation points, and some other high-l more sequence parameter sets.</dd>
evel properties of the bitstream that can be used as the basis for session negot <dt>Sequence parameter set</dt>
iation and content selection, etc. One VPS may be referenced by one or more sequ <dd>The sequence parameter set (SPS) contains syntax elements pertaini
ence parameter sets.</t> ng to a coded layer video sequence (CLVS), which is a group of pictures belongin
g to the same layer, starting with a random access point, and followed by pictur
<t>Sequence parameter set</t> es that may depend on each other until the next random access point picture. In
MPEG-2, the equivalent of a CVS was a group of pictures (GOP), which normally st
<t>The sequence parameter set (SPS) contains syntax elements pertaining to a cod arted with an I frame and was followed by P and B frames. While more complex in
ed layer video sequence (CLVS), which is a group of pictures belonging to the sa its options of random access points, VVC retains this basic concept. One remarka
me layer, starting with a random access point, and followed by pictures that may ble difference of VVC is that a CLVS may start with a Gradual Decoding Refresh (
depend on each other, until the next random access point picture. In MPEG-2, th GDR) picture without requiring presence of traditional random access points in t
e equivalent of a CVS was a group of pictures (GOP), which normally started with he bitstream, such as instantaneous decoding refresh (IDR) or clean random acces
an I frame and was followed by P and B frames. While more complex in its option s (CRA) pictures. In many TV-like applications, a CVS contains a few hundred mil
s of random access points, VVC retains this basic concept. One remarkable differ liseconds to a few seconds of video. In video conferencing (without switching Mu
ence of VVC is that a CLVS may start with a Gradual Decoding Refresh (GDR) pictu ltipoint Control Units (MCUs) involved), a CVS can be as long in duration as the
re, without requiring presence of traditional random access points in the bitstr whole session.</dd>
eam, such as instantaneous decoding refresh (IDR) or clean random access (CRA) p <dt>Picture and adaptation parameter set</dt>
ictures. In many TV-like applications, a CVS contains a few hundred milliseconds <dd>The picture parameter set (PPS) and the adaptation parameter set (
to a few seconds of video. In video conferencing (without switching MCUs involv APS) carry information pertaining to zero or more pictures and zero or more sli
ed), a CVS can be as long in duration as the whole session.</t> ces, respectively. The PPS contains information that is likely to stay constant
from picture to picture, at least for pictures for a certain type, whereas the A
<t>  PS contains information, such as adaptive loop filter coefficients, that are lik
 </t> ely to change from picture to picture or even within a picture. A single APS is
referenced by all slices of the same picture if that APS contains information ab
<t>Picture and adaptation parameter set</t> out luma mapping with chroma scaling (LMCS) or a scaling list. Different APSs co
ntaining ALF parameters can be referenced by slices of the same picture.</dd>
<t>The picture parameter set and the adaptation parameter set (PPS and APS, resp <dt>Picture header</dt>
ectively) carry information pertaining to zero or more pictures and zero or mor <dd>A picture header (PH) contains information that is common to all s
e slices, respectively. The PPS contains information that is likely to stay cons lices that belong to the same picture. Being able to send that information as a
tant from picture to picture, at least for pictures for a certain type-whereas t separate NAL unit when pictures are split into several slices allows for saving
he APS contains information, such as adaptive loop filter coefficients, that are bitrate, compared to repeating the same information in all slices. However, ther
likely to change from picture to picture or even within a picture. A single APS e might be scenarios where low-bitrate video is transmitted using a single slice
is referenced by all slices of the same picture if that APS contains informatio per picture. Having a separate NAL unit to convey that information incurs in an
n about luma mapping with chroma scaling (LMCS) or scaling list. Different APSs overhead for such scenarios. For such scenarios, the picture header syntax stru
containing ALF parameters can be referenced by slices of the same picture.</t> cture is directly included in the slice header, instead of its own NAL unit. The
mode of the picture header syntax structure being included in its own NAL unit
<t>Picture header</t> or not can only be switched on/off for an entire CLVS and can only be switched o
ff when, in the entire CLVS, each picture contains only one slice.</dd>
<t>A Picture Header contains information that is common to all slices that belon <dt>Profile, tier, and level</dt>
g to the same picture. Being able to send that information as a separate NAL uni <dd>The profile, tier, and level syntax structures in DCI, VPS, and SP
t when pictures are split into several slices allows for saving bitrate, compare S
d to repeating the same information in all slices. However, there might be scena contain profile, tier, and level information for all layers that refer
rios where low-bitrate video is transmitted using a single slice per picture. Ha
ving a separate NAL unit to convey that information incurs in an overhead for su
ch scenarios. For such scenarios, the picture header syntax structure is directl
y included in the slice header, instead of its own NAL unit. The mode of the pic
ture header syntax structure being included in its own NAL unit or not can only
be switched on/off for an entire CLVS, and can only be switched off when in the
entire CLVS each picture contains only one slice.</t>
<t>Profile, tier, and level</t>
<t>The profile, tier and level syntax structures in DCI, VPS and SPS
contain profile, tier, level information for all layers that refer
to the DCI, for layers associated with one or more output layer to the DCI, for layers associated with one or more output layer
sets specified by the VPS, and for any layer sets specified by the VPS, and for any layer
that refers to the SPS, respectively.</t> that refers to the SPS, respectively.</dd>
<dt>Sub-profiles</dt>
<t>Sub-profiles</t> <dd>Within the VVC specification, a sub-profile is a 32-bit number, co
ded according to ITU-T Recommendation T.35, that does not carry semantics. It is
<t>Within the VVC specification, a sub-profile is a 32-bit number, coded accordi carried in the profile_tier_level structure and hence is (potentially) present
ng to ITU-T Rec. T.35, that does not carry a semantics. It is carried in the pro in the DCI, VPS, and SPS. External registration bodies can register a T.35 codep
file_tier_level structure and hence (potentially) present in the DCI, VPS, and S oint with ITU-T registration authorities and associate with their registration a
PS. External registration bodies can register a T.35 codepoint with ITU-T regist description of bitstream restrictions beyond the profiles defined by ITU-T and
ration authorities and associate with their registration a description of bitstr ISO/IEC. This would allow encoder manufacturers to label the bitstreams generate
eam restrictions beyond the profiles defined by ITU-T and ISO/IEC. This would al d by their encoder as complying with such sub-profile. It is expected that upstr
low encoder manufacturers to label the bitstreams generated by their encoder as eam standardization organizations (such as Digital Video Broadcasting (DVB) and
complying with such sub-profile. It is expected that upstream standardization or Advanced Television Systems Committee (ATSC)), as well as walled-garden video se
ganizations (such as: DVB and ATSC), as well as walled-garden video services wil rvices, will take advantage of this labeled system. In contrast to "normal" prof
l take advantage of this labeled system. In contrast to "normal" profiles, it is iles, it is expected that sub-profiles may indicate encoder choices traditionall
expected that sub-profiles may indicate encoder choices traditionally left open y left open in the (decoder-centric) video coding specifications, such as GOP st
in the (decoder-centric) video coding specs, such as GOP structures, minimum/ma ructures, minimum/maximum Quantizer Parameter (QP) values, and the mandatory use
ximum QP values, and the mandatory use of certain tools or SEI messages.</t> of certain tools or SEI messages.</dd>
<dt>General constraint fields</dt>
<ul empty="true"><li> <dd>The profile_tier_level structure carries a considerable number of
constraint fields (most of which are flags), which an encoder can use to indicat
</li></ul> e to a decoder that it will not use a certain tool or technology. They were incl
uded in reaction to a perceived market need to label a bitstream as not exercisi
<t>General constraint fields</t> ng a certain tool that has become commercially unviable.</dd>
<dt>Temporal scalability support</dt>
<t>The profile_tier_level structure carries a considerable number of constraint <dd>VVC includes support of temporal scalability, by the inclusion of
fields (most of which are flags), which an encoder can use to indicate to a deco the signaling of TemporalId in the NAL unit header, the restriction that picture
der that it will not use a certain tool or technology. They were included in rea s of a particular temporal sublayer cannot be used for inter prediction referenc
ction to a perceived market need for labeled a bitstream as not exercising a cer e by pictures of a lower temporal sublayer, the sub-bitstream extraction process
tain tool that has become commercially unviable.</t> , and the requirement that each sub-bitstream extraction output be a conforming
bitstream. Media-Aware Network Elements (MANEs) can utilize the TemporalId in th
<t>Temporal scalability support</t> e NAL unit header for stream adaptation purposes based on temporal scalability.<
/dd>
<t>VVC includes support of temporal scalability, by inclusion of the signaling o <dt>Reference picture resampling (RPR)</dt>
f TemporalId in the NAL unit header, the restriction that pictures of a particul <dd>In AVC and HEVC, the spatial resolution of pictures cannot change
ar temporal sublayer cannot be used for inter prediction reference by pictures o unless a new sequence using a new SPS starts, with an intra random access point
f a lower temporal sublayer, the sub-bitstream extraction process, and the requi (IRAP) picture. VVC enables picture resolution change within a sequence at a pos
rement that each sub-bitstream extraction output be a conforming bitstream. Medi ition without encoding an IRAP picture, which is always intra coded. This featur
a-Aware Network Elements (MANEs) can utilize the TemporalId in the NAL unit head e is sometimes referred to as reference picture resampling (RPR), as the feature
er for stream adaptation purposes based on temporal scalability.</t> needs resampling of a reference picture used for inter prediction when that ref
erence picture has a different resolution than the current picture being decoded
<t>Reference picture resampling (RPR)</t> . RPR allows resolution change without the need of coding an IRAP picture and he
nce avoids a momentary bit rate spike caused by an IRAP picture in streaming or
<t>In AVC and HEVC, the spatial resolution of pictures cannot change unless a ne video conferencing scenarios, e.g., to cope with network condition changes. RPR
w sequence using a new SPS starts, with an Intra random access point (IRAP) pict can also be used in application scenarios wherein zooming of the entire video r
ure. VVC enables picture resolution change within a sequence at a position witho egion or some region of interest is needed.</dd>
ut encoding an IRAP picture, which is always intra-coded. This feature is someti <dt>Spatial, SNR, and multiview scalability</dt>
mes referred to as reference picture resampling (RPR), as the feature needs resa <dd><t>VVC includes support for spatial, SNR, and multiview scalabilit
mpling of a reference picture used for inter prediction when that reference pict y. Scalable video coding is widely considered to have technical benefits and enr
ure has a different resolution than the current picture being decoded. RPR allow ich services for various video applications. Until recently, however, the functi
s resolution change without the need of coding an IRAP picture and hence avoids onality has not been included in the first version of specifications of the vide
a momentary bit rate spike caused by an IRAP picture in streaming or video confe o codecs. In VVC, however, all those forms of scalability are supported in the f
rencing scenarios, e.g., to cope with network condition changes. RPR can also b irst version of VVC natively through the signaling of the nuh_layer_id in the NA
e used in application scenarios wherein zooming of the entire video region or so L unit header, the VPS that associates layers with the given nuh_layer_id to eac
me region of interest is needed.</t> h other, reference picture selection, reference picture resampling for spatial s
calability, and a number of other mechanisms not relevant for this memo.</t>
<ul empty="true"><li> <dl newline="true" spacing="normal">
<dt>Spatial scalability</dt>
</li></ul> <dd>With the existence of reference picture resampling (RPR), the
additional burden for scalability support is just a modification of the high-lev
<t>Spatial, SNR, and multiview scalability</t> el syntax (HLS). The inter-layer prediction is employed in a scalable system to
improve the coding efficiency of the enhancement layers. In addition to the spat
<t>VVC includes support for spatial, SNR, and multiview scalability. Scalable vi ial and temporal motion-compensated predictions that are available in a single-l
deo coding is widely considered to have technical benefits and enrich services f ayer codec, the inter-layer prediction in VVC uses the possibly resampled video
or various video applications. Until recently, however, the functionality has no data of the reconstructed reference picture from a reference layer to predict th
t been included in the first version of specifications of the video codecs. In V e current enhancement layer. The resampling process for inter-layer prediction,
VC, however, all those forms of scalability are supported in the first version o when used, is performed at the block level, reusing the existing interpolation p
f VVC natively through the signaling of the nuh_layer_id in the NAL unit header, rocess for motion compensation in single-layer coding. It means that no addition
the VPS which associates layers with given nuh_layer_id to each other, referenc al resampling process is needed to support spatial scalability.</dd>
e picture selection, reference picture resampling for spatial scalability, and a <dt>SNR scalability</dt>
number of other mechanisms not relevant for this memo.</t> <dd>SNR scalability is similar to spatial scalability except that
the resampling factors are 1:1. In other words, there is no change in resolution
<ul empty="true"><li> , but there is inter-layer prediction.</dd>
<t>Spatial scalability</t> <dt>Multiview scalability</dt>
<dd>The first version of VVC also supports multiview scalability,
<ul empty="true"><li> wherein a multi-layer bitstream carries layers representing multiple views, and
<t>With the existence of Reference Picture Resampling (RPR), the additional one or more of the represented views can be output at the same time.</dd>
burden for scalability support is just a modification of the high-level syntax ( </dl>
HLS). The inter-layer prediction is employed in a scalable system to improve the </dd>
coding efficiency of the enhancement layers. In addition to the spatial and tem <dt>SEI messages</dt>
poral motion-compensated predictions that are available in a single-layer codec, <dd>Supplemental enhancement information (SEI) messages are informatio
the inter-layer prediction in VVC uses the possibly resampled video data of the n in the bitstream that do not influence the decoding process as specified in th
reconstructed reference picture from a reference layer to predict the current e e VVC specification but address issues of representation/rendering of the decode
nhancement layer. The resampling process for inter-layer prediction, when used, d bitstream, label the bitstream for certain applications, and other, similar ta
is performed at the block-level, reusing the existing interpolation process for sks. The overall concept of SEI messages and many of the messages themselves has
motion compensation in single-layer coding. It means that no additional resampli been inherited from the AVC and HEVC specifications. Except for the SEI message
ng process is needed to support spatial scalability.</t> s that affect the specification of the hypothetical reference decoder (HRD), oth
</li></ul> er SEI messages for use in the VVC environment, which are generally useful also
</li></ul> in other video coding technologies, are not included in the main VVC specificati
on but in a companion specification <xref target="VSEI"/>.</dd>
<ul empty="true"><li> </dl>
<t>SNR scalability</t> </section>
</li></ul> <section anchor="high-level-picture-partitioning-informative">
<name>High-Level Picture Partitioning (Informative)</name>
<ul empty="true"><li> <t>VVC inherited the concept of tiles and wavefront parallel processin
<ul empty="true"><li> g (WPP) from HEVC, with some minor to moderate differences. The basic concept of
<t>SNR scalability is similar to spatial scalability except that the resampl slices was kept in VVC but designed in an essentially different form. VVC is th
ing factors are 1:1. In other words, there is no change in resolution, but there e first video coding standard that includes subpictures as a feature, which prov
is inter-layer prediction.</t> ides the same functionality as HEVC motion-constrained tile sets (MCTSs) but des
</li></ul> igned differently to have better coding efficiency and to be friendlier for usag
</li></ul> e in application systems. More details of these differences are described below.
</t>
<ul empty="true"><li> <dl newline="true" spacing="normal">
<t>Multiview scalability</t> <dt>Tiles and WPP</dt>
</li></ul> <dd>Same as in HEVC, a picture can be split into tile rows and tile
columns in VVC, in-picture prediction across tile boundaries is disallowed, etc.
<ul empty="true"><li> However, the syntax for signaling of tile partitioning has been simplified by u
<ul empty="true"><li> sing a unified syntax design for both the uniform and the non-uniform mode. In a
<t>The first version of VVC also supports multiview scalability, wherein a m ddition, signaling of entry point offsets for tiles in the slice header is optio
ulti-layer bitstream carries layers representing multiple views, and one or more nal in VVC, while it is mandatory in HEVC. The WPP design in VVC has two differe
of the represented views can be output at the same time.</t> nces compared to HEVC: i) the CTU row delay is reduced from two CTUs to one CTU,
</li></ul> and ii) signaling of entry point offsets for WPP in the slice header is optiona
</li></ul> l in VVC while it is mandatory in HEVC.</dd>
<dt>Slices</dt>
<t>SEI messages</t> <dd><t>In VVC, the conventional slices based on CTUs (as in HEVC) or m
acroblocks (as in AVC) have been removed. The main reasoning behind this archite
<t>Supplemental enhancement information (SEI) messages are information in the bi ctural change is as follows. The advances in video coding since 2003 (the public
tstream that do not influence the decoding process as specified in the VVC spec, ation year of AVC v1) have been such that slice-based error concealment has beco
but address issues of representation/rendering of the decoded bitstream, label me practically impossible due to the ever-increasing number and efficiency of in
the bitstream for certain applications, among other, similar tasks. The overall -picture and inter-picture prediction mechanisms. An error-concealed picture is
concept of SEI messages and many of the messages themselves has been inherited f the decoding result of a transmitted coded picture for which there is some data
rom the AVC and HEVC specs. Except for the SEI messages that affect the specific loss (e.g., loss of some slices) of the coded picture or a reference picture, as
ation of the hypothetical reference decoder (HRD), other SEI messages for use in at least some part of the coded picture is not error-free (e.g., that reference
the VVC environment, which are generally useful also in other video coding tech picture was an error-concealed picture). For example, when one of the multiple
nologies, are not included in the main VVC specification but in a companion spec slices of a picture is lost, it may be error-concealed using an interpolation of
ification <xref target="VSEI"/>.</t> the neighboring slices. While advanced video coding prediction mechanisms provi
de significantly higher coding efficiency, they also make it harder for machines
</section> to estimate the quality of an error-concealed picture, which was already a hard
<section anchor="high-level-picture-partitioning-informative"><name>High-Level P problem with the use of simpler prediction mechanisms. Advanced in-picture pred
icture Partitioning (informative)</name> iction mechanisms also cause the coding efficiency loss due to splitting a pictu
re into multiple slices to be more significant. Furthermore, network conditions
<t>VVC inherited the concept of tiles and wavefront parallel processing (WPP) fr become significantly better while, at the same time, techniques for dealing with
om HEVC, with some minor to moderate differences. The basic concept of slices wa packet losses have become significantly improved. As a result, very few impleme
s kept in VVC but designed in an essentially different form. VVC is the first vi ntations have recently used slices for maximum-transmission-unit-size matching.
deo coding standard that includes subpictures as a feature, which provides the s Instead, substantially all applications where low-delay error resilience is requ
ame functionality as HEVC motion-constrained tile sets (MCTSs) but designed diff ired (e.g., video telephony and video conferencing) rely on system/transport-lev
erently to have better coding efficiency and to be friendlier for usage in appli el error resilience (e.g., retransmission or forward error correction) and/or pi
cation systems. More details of these differences are described below.</t> cture-based error resilience tools (e.g., feedback-based error resilience, inser
tion of IRAPs, scalability with a higher protection level of the base layer, and
<t>Tiles and WPP</t> so on). Considering all the above, nowadays, it is very rare that a picture tha
t cannot be correctly decoded is passed to the decoder, and when such a rare cas
<t>Same as in HEVC, a picture can be split into tile rows and tile columns in VV e occurs, the system can afford to wait for an error-free picture to be decoded
C, in-picture prediction across tile boundaries is disallowed, etc. However, the and available for display without resulting in frequent and long periods of pict
syntax for signaling of tile partitioning has been simplified, by using a unifi ure freezing seen by end users.</t>
ed syntax design for both the uniform and the non-uniform mode. In addition, sig <t>Slices in VVC have two modes: rectangular slices and raster-scan sl
naling of entry point offsets for tiles in the slice header is optional in VVC w ices. The rectangular slice, as indicated by its name, covers a rectangular regi
hile it is mandatory in HEVC. The WPP design in VVC has two differences compared on of the picture. Typically, a rectangular slice consists of several complete t
to HEVC: i) The CTU row delay is reduced from two CTUs to one CTU; ii) signalin iles. However, it is also possible that a rectangular slice is a subset of a til
g of entry point offsets for WPP in the slice header is optional in VVC while it e and consists of one or more consecutive, complete CTU rows within a tile. A ra
is mandatory in HEVC.</t> ster-scan slice consists of one or more complete tiles in a tile raster-scan ord
er; hence, the region covered by raster-scan slices need not but could have a no
<t>Slices</t> n-rectangular shape, but it may also happen to have the shape of a rectangle. Th
e concept of slices in VVC is therefore strongly linked to or based on tiles ins
<t>In VVC, the conventional slices based on CTUs (as in HEVC) or macroblocks (as tead of CTUs (as in HEVC) or macroblocks (as in AVC).</t></dd>
in AVC) have been removed. The main reasoning behind this architectural change <dt>Subpictures</dt>
is as follows. The advances in video coding since 2003 (the publication year of <dd><t>VVC is the first video coding standard that includes the suppor
AVC v1) have been such that slice-based error concealment has become practically t of subpictures as a feature. Each subpicture consists of one or more complete
impossible, due to the ever-increasing number and efficiency of in-picture and rectangular slices that collectively cover a rectangular region of the picture.
inter-picture prediction mechanisms. An error-concealed picture is the decoding A subpicture may be either specified to be extractable (i.e., coded independentl
result of a transmitted coded picture for which there is some data loss (e.g., l y of other subpictures of the same picture and of earlier pictures in decoding o
oss of some slices) of the coded picture or a reference picture for at least som rder) or not extractable. Regardless of whether a subpicture is extractable or n
e part of the coded picture is not error-free (e.g., that reference picture was ot, the encoder can control whether in-loop filtering (including deblocking, SAO
an error-concealed picture). For example, when one of the multiple slices of a p , and ALF) is applied across the subpicture boundaries individually for each sub
icture is lost, it may be error-concealed using an interpolation of the neighbor picture.</t>
ing slices. While advanced video coding prediction mechanisms provide significan <t>Functionally, subpictures are similar to the motion-constrained til
tly higher coding efficiency, they also make it harder for machines to estimate e sets (MCTSs) in HEVC. They both allow independent coding and extraction of a r
the quality of an error-concealed picture, which was already a hard problem with ectangular subset of a sequence of coded pictures for use cases like viewport-de
the use of simpler prediction mechanisms. Advanced in-picture prediction mechan pendent 360-degree video streaming optimization and region of interest (ROI) app
isms also cause the coding efficiency loss due to splitting a picture into multi lications.</t>
ple slices to be more significant. Furthermore, network conditions become signif <t>There are several important design differences between subpictures
icantly better while at the same time techniques for dealing with packet losses and MCTSs. First, the subpictures featured in VVC allow motion vectors of a codi
have become significantly improved. As a result, very few implementations have r ng block to point outside of the subpicture, even when the subpicture is extract
ecently used slices for maximum transmission unit size matching. Instead, substa able by applying sample padding at the subpicture boundaries, in this case, simi
ntially all applications where low-delay error resilience is required (e.g., vid larly as at picture boundaries. Second, additional changes were introduced for t
eo telephony and video conferencing) rely on system/transport-level error resili he selection and derivation of motion vectors in the merge mode and in the decod
ence (e.g., retransmission, forward error correction) and/or picture-based error er-side motion vector refinement process of VVC. This allows higher coding effic
resilience tools (feedback-based error resilience, insertion of IRAPs, scalabil iency compared to the non-normative motion constraints applied at the encoder-si
ity with higher protection level of the base layer, and so on). Considering all de for MCTSs. Third, rewriting of slice headers (SHs) (and PH NAL units, when pr
the above, nowadays it is very rare that a picture that cannot be correctly deco esent) is not needed when extracting one or more extractable subpictures from a
ded is passed to the decoder, and when such a rare case occurs, the system can a sequence of pictures to create a sub-bitstream that is a conforming bitstream. I
fford to wait for an error-free picture to be decoded and available for display n sub-bitstream extractions based on HEVC MCTSs, rewriting of SHs is needed. Not
without resulting in frequent and long periods of picture freezing seen by end u e that, in both HEVC MCTSs extraction and VVC subpictures extraction, rewriting
sers.</t> of SPSs and PPSs is needed. However, typically, there are only a few parameter s
ets in a bitstream, whereas each picture has at least one slice; therefore, rewr
<t>Slices in VVC have two modes: rectangular slices and raster-scan slices. The iting of SHs can be a significant burden for application systems. Fourth, slices
rectangular slice, as indicated by its name, covers a rectangular region of the of different subpictures within a picture are allowed to have different NAL uni
picture. Typically, a rectangular slice consists of several complete tiles. Howe t types. Fifth, VVC specifies HRD and level definitions for subpicture sequences
ver, it is also possible that a rectangular slice is a subset of a tile and cons , thus the conformance of the sub-bitstream of each extractable subpicture seque
ists of one or more consecutive, complete CTU rows within a tile. A raster-scan nce can be ensured by encoders.</t></dd>
slice consists of one or more complete tiles in a tile raster scan order, hence </dl>
the region covered by a raster-scan slices need not but could have a non-rectang </section>
ular shape, but it may also happen to have the shape of a rectangle. The concept <section anchor="NALUnitHeader">
of slices in VVC is therefore strongly linked to or based on tiles instead of C <name>NAL Unit Header</name>
TUs (as in HEVC) or macroblocks (as in AVC).</t> <t>VVC maintains the NAL unit concept of HEVC with modifications. VVC
<t>Subpictures</t>
<t>VVC is the first video coding standard that includes the support of subpictur
es as a feature. Each subpicture consists of one or more complete rectangular sl
ices that collectively cover a rectangular region of the picture. A subpicture m
ay be either specified to be extractable (i.e., coded independently of other sub
pictures of the same picture and of earlier pictures in decoding order) or not e
xtractable. Regardless of whether a subpicture is extractable or not, the encode
r can control whether in-loop filtering (including deblocking, SAO, and ALF) is
applied across the subpicture boundaries individually for each subpicture.</t>
<t>Functionally, subpictures are similar to the motion-constrained tile sets (MC
TSs) in HEVC. They both allow independent coding and extraction of a rectangular
subset of a sequence of coded pictures, for use cases like viewport-dependent 3
60° video streaming optimization and region of interest (ROI) applications.</t>
<t>There are several important design differences between subpictures and MCTSs.
First, the subpictures feature in VVC allows motion vectors of a coding block p
ointing outside of the subpicture even when the subpicture is extractable by app
lying sample padding at subpicture boundaries in this case, similarly as at pict
ure boundaries. Second, additional changes were introduced for the selection and
derivation of motion vectors in the merge mode and in the decoder side motion v
ector refinement process of VVC. This allows higher coding efficiency compared t
o the non-normative motion constraints applied at the encoder-side for MCTSs. Th
ird, rewriting of SHs (and PH NAL units, when present) is not needed when extrac
ting one or more extractable subpictures from a sequence of pictures to create a
sub-bitstream that is a conforming bitstream. In sub-bitstream extractions base
d on HEVC MCTSs, rewriting of SHs is needed. Note that in both HEVC MCTSs extrac
tion and VVC subpictures extraction, rewriting of SPSs and PPSs is needed. Howev
er, typically there are only a few parameter sets in a bitstream, while each pic
ture has at least one slice, therefore rewriting of SHs can be a significant bur
den for application systems. Fourth, slices of different subpictures within a pi
cture are allowed to have different NAL unit types. Fifth, VVC specifies HRD and
level definitions for subpicture sequences, thus the conformance of the sub-bit
stream of each extractable subpicture sequence can be ensured by encoders.</t>
</section>
<section anchor="NALUnitHeader"><name>NAL Unit Header</name>
<t>VVC maintains the NAL unit concept of HEVC with modifications. VVC
uses a two-byte NAL unit header, as shown in <xref target="vvc-nuh"/>. The payl oad uses a two-byte NAL unit header, as shown in <xref target="vvc-nuh"/>. The payl oad
of a NAL unit refers to the NAL unit excluding the NAL unit header.</t> of a NAL unit refers to the NAL unit excluding the NAL unit header.</t>
<figure anchor="vvc-nuh">
<figure anchor="vvc-nuh"><artwork><![CDATA[ <name>The Structure of the VVC NAL Unit Header</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
+---------------+---------------+ +---------------+---------------+
|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7| |0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F|Z| LayerID | Type | TID | |F|Z| LayerID | Type | TID |
+---------------+---------------+ +---------------+---------------+
]]></artwork>
The Structure of the VVC NAL Unit Header. </figure>
<t>The semantics of the fields in the NAL unit header are as specified
]]></artwork></figure>
<t>The semantics of the fields in the NAL unit header are as specified
in VVC and described briefly below for convenience. In addition to in VVC and described briefly below for convenience. In addition to
the name and size of each field, the corresponding syntax element the name and size of each field, the corresponding syntax element
name in VVC is also provided.</t> name in VVC is also provided.</t>
<dl newline="true" spacing="normal">
<ul empty="true"><li> <dt>F: 1 bit</dt>
<dd>forbidden_zero_bit. This field is required to be zero in VVC. No
</li></ul> te that the
<t>F: 1 bit</t>
<ul empty="true"><li>
<t>forbidden_zero_bit. Required to be zero in VVC. Note that the
inclusion of this bit in the NAL unit header was to enable inclusion of this bit in the NAL unit header was to enable
transport of VVC video over MPEG-2 transport systems (avoidance transport of VVC video over MPEG-2 transport systems (avoidance
of start code emulations) <xref target="MPEG2S"/>. In the context of this paylo ad format, of start code emulations) <xref target="MPEG2S"/>. In the context of this paylo ad format,
the value 1 may be used to indicate a syntax violation, e.g., for the value 1 may be used to indicate a syntax violation, e.g., for
a NAL unit resulted from aggregating a number of fragmented units a NAL unit resulted from aggregating a number of fragmented units
of a NAL unit but missing the last fragment, as described in the last sentence o of a NAL unit but missing the last fragment, as described in the last sentence o
f section 4.3.3.</t> f <xref target="funits"/>.</dd>
</li></ul> <dt>Z: 1 bit</dt>
<dd>nuh_reserved_zero_bit. This field is required to be zero in VVC,
<t>Z: 1 bit</t> and reserved
for future extensions by ITU-T and ISO/IEC.<br/>
<ul empty="true"><li> This memo does not overload the "Z" bit for local extensions a)
<t>nuh_reserved_zero_bit. Required to be zero in VVC, and reserved because overloading the "F" bit is sufficient and b)
for future extensions by ITU-T and ISO/IEC.<br /> in order to preserve the usefulness of this memo to possible future versions
This memo does not overload the "Z" bit for local extensions, as a) of <xref target="VVC"/>.</dd>
overloading the "F" bit is sufficient and b) <dt>LayerId: 6 bits</dt>
to preserve the usefulness of this memo to possible future versions <dd>nuh_layer_id. This field identifies the layer a NAL unit belongs
of <xref target="VVC"/>.</t> to, wherein
</li></ul>
<t>LayerId: 6 bits</t>
<ul empty="true"><li>
<t>nuh_layer_id. Identifies the layer a NAL unit belongs to, wherein
a layer may be, e.g., a spatial scalable layer, a quality scalable a layer may be, e.g., a spatial scalable layer, a quality scalable
layer, a layer containing a different view, etc.</t> layer, a layer containing a different view, etc.</dd>
</li></ul> <dt>Type: 5 bits</dt>
<dd>nal_unit_type. This field specifies the NAL unit type, as defined
<t>Type: 5 bits</t>
<ul empty="true"><li>
<t>nal_unit_type. This field specifies the NAL unit type as defined
in Table 5 of <xref target="VVC"/>. For a reference of all currently defined in Table 5 of <xref target="VVC"/>. For a reference of all currently defined
NAL unit types and their semantics, please refer to NAL unit types and their semantics, please refer to
Section 7.4.2.2 in <xref target="VVC"/>.</t> Section 7.4.2.2 in <xref target="VVC"/>.</dd>
</li></ul> <dt>TID: 3 bits</dt>
<dd>nuh_temporal_id_plus1. This field specifies the temporal
<t>TID: 3 bits</t>
<ul empty="true"><li>
<t>nuh_temporal_id_plus1. This field specifies the temporal
identifier of the NAL unit plus 1. The value of TemporalId is identifier of the NAL unit plus 1. The value of TemporalId is
equal to TID minus 1. A TID value of 0 is illegal to ensure that equal to TID minus 1. A TID value of 0 is illegal to ensure that
there is at least one bit in the NAL unit header equal to 1, so to enable the co there is at least one bit in the NAL unit header equal to 1 in order to enable t
nsideration of start code emulations in the NAL unit payload data independent of he consideration of start code emulations in the NAL unit payload data independe
the NAL unit header.</t> nt of the NAL unit header.</dd>
</li></ul> </dl>
</section>
</section> </section>
</section> <section anchor="overview-of-the-payload-format">
<section anchor="overview-of-the-payload-format"><name>Overview of the Payload F <name>Overview of the Payload Format</name>
ormat</name> <t>This payload format defines the following processes required for
<t>This payload format defines the following processes required for
transport of VVC coded data over RTP <xref target="RFC3550"/>:</t> transport of VVC coded data over RTP <xref target="RFC3550"/>:</t>
<ul spacing="normal">
<t><list style="symbols"> <li>usage of the RTP header with this payload format</li>
<t>Usage of RTP header with this payload format</t> <li>packetization of VVC coded NAL units into RTP packets using
<t>Packetization of VVC coded NAL units into RTP packets using
three types of payload structures: a single NAL unit packet, three types of payload structures: a single NAL unit packet,
aggregation packet, and fragment unit</t> aggregation packet, and fragment unit</li>
<t>Transmission of VVC NAL units of the same bitstream within a <li>transmission of VVC NAL units of the same bitstream within a
single RTP stream</t> single RTP stream</li>
<t>Media type parameters to be used with the Session Description <li>media type parameters to be used with the Session Description
Protocol (SDP) <xref target="RFC8866"/></t> Protocol (SDP) <xref target="RFC8866"/></li>
<t>Usage of RTCP feedback messages</t> <li>usage of RTCP feedback messages</li>
</list></t> </ul>
</section>
</section> </section>
</section> <section anchor="conventions">
<section anchor="conventions"><name>Conventions</name> <name>Conventions</name>
<t>The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", >REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>
"SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this d SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bc
ocument are to be interpreted as described in BCP 14 <xref target="RFC2119"/> <x p14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>
ref target="RFC8174"/> when, and only when, they appear in all capitals, as show " in this document are to be interpreted as described in BCP 14 <xref target="RF
n here.</t> C2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capita
ls, as shown here.</t>
</section> </section>
<section anchor="definitionsandabbr"><name>Definitions and Abbreviations</name> <section anchor="definitionsandabbr">
<name>Definitions and Abbreviations</name>
<section anchor="definitions"><name>Definitions</name> <section anchor="definitions">
<t>This document uses the terms and definitions of VVC. <xref target="definitio <name>Definitions</name>
nforvvc"/> <t>This document uses the terms and definitions of VVC. <xref target="d
efinitionforvvc"/>
lists relevant definitions from <xref target="VVC"/> for convenience. <xref tar get="def"/> lists relevant definitions from <xref target="VVC"/> for convenience. <xref tar get="def"/>
provides definitions specific to this memo. All the used terms and definitions provides definitions specific to this memo. All the used terms and definitions
in this memo are verbatim copies of <xref target="VVC"/> specification.</t> in this memo are verbatim copies from the <xref target="VVC"/> specificat
ion.</t>
<section anchor="definitionforvvc"><name>Definitions from the VVC Specification< <!-- Start of DNE "All the used terms and definitions in this memo are verbatim
/name> copies from the VVC specification.
-->
<t>Access unit (AU): A set of PUs that belong to different layers and <section anchor="definitionforvvc">
<name>Definitions from the VVC Specification</name>
<dl newline="true" spacing="normal">
<dt>Access unit (AU):</dt>
<dd>A set of PUs that belong to different layers and
contain coded pictures associated with the same time for output contain coded pictures associated with the same time for output
from the DPB.</t> from the DPB.</dd>
<dt>Adaptation parameter set (APS):</dt>
<t>Adaptation parameter set (APS): A syntax structure containing syntax <dd>A syntax structure containing syntax
elements that apply to zero or more slices as determined by zero or elements that apply to zero or more slices as determined by zero or
more syntax elements found in slice headers.</t> more syntax elements found in slice headers.</dd>
<dt>Bitstream:</dt>
<t>Bitstream: A sequence of bits, in the form of a NAL unit stream or <dd>A sequence of bits, in the form of a NAL unit stream or
a byte stream, that forms the representation of a sequence of AUs a byte stream, that forms the representation of a sequence of AUs
forming one or more coded video sequences (CVSs).</t> forming one or more coded video sequences (CVSs).</dd>
<dt>Coded picture:</dt>
<t>Coded picture: A coded representation of a picture comprising VCL <dd>A coded representation of a picture comprising VCL
NAL units with a particular value of nuh_layer_id within an AU and NAL units with a particular value of nuh_layer_id within an AU and
containing all CTUs of the picture.</t> containing all CTUs of the picture.</dd>
<dt>Clean random access (CRA) PU:</dt>
<t>Clean random access (CRA) PU: A PU in which the coded picture is a <dd>A PU in which the coded picture is a
CRA picture.</t> CRA picture.</dd>
<dt>Clean random access (CRA) picture:</dt>
<t>Clean random access (CRA) picture: An IRAP picture for which each <dd>An IRAP picture for which each
VCL NAL unit has nal_unit_type equal to CRA_NUT.</t> VCL NAL unit has nal_unit_type equal to CRA_NUT.</dd>
<dt>Coded video sequence (CVS):</dt>
<t>Coded video sequence (CVS): A sequence of AUs that consists, in <dd>A sequence of AUs that consists, in
decoding order, of a CVSS AU, followed by zero or more AUs that are decoding order, of a CVSS AU, followed by zero or more AUs that are
not CVSS AUs, including all subsequent AUs up to but not including not CVSS AUs, including all subsequent AUs up to but not including
any subsequent AU that is a CVSS AU.</t> any subsequent AU that is a CVSS AU.</dd>
<dt>Coded video sequence start (CVSS) AU:</dt>
<t>Coded video sequence start (CVSS) AU: An AU in which there is a PU <dd>An AU in which there is a PU
for each layer in the CVS and the coded picture in each PU is a CLVSS for each layer in the CVS and the coded picture in each PU is a CLVSS
picture.</t> picture.</dd>
<dt>Coded layer video sequence (CLVS):</dt>
<t>Coded layer video sequence (CLVS): A sequence of PUs with the same <dd>A sequence of PUs with the same
value of nuh_layer_id that consists, in decoding order, of a CLVSS PU, value of nuh_layer_id that consists, in decoding order, of a CLVSS PU,
followed by zero or more PUs that are not CLVSS PUs, including all followed by zero or more PUs that are not CLVSS PUs, including all
subsequent PUs up to but not including any subsequent PU that is a subsequent PUs up to but not including any subsequent PU that is a
CLVSS PU.</t> CLVSS PU.</dd>
<dt>Coded layer video sequence start (CLVSS) PU:</dt>
<t>Coded layer video sequence start (CLVSS) PU: A PU in which the coded <dd>A PU in which the coded
picture is a CLVSS picture.</t> picture is a CLVSS picture.</dd>
<dt>Coded layer video sequence start (CLVSS) picture:</dt>
<t>Coded layer video sequence start (CLVSS) picture: A coded picture that is an <dd>A coded picture that is an IRAP picture with NoOutputBeforeRecover
IRAP picture with NoOutputBeforeRecoveryFlag equal to 1 or a GDR picture with No yFlag equal to 1 or a GDR picture with NoOutputBeforeRecoveryFlag equal to 1.</d
OutputBeforeRecoveryFlag equal to 1.</t> d>
<dt>Coding Tree Block (CTB):</dt>
<t>Coding tree unit (CTU): A CTB of luma samples, two corresponding CTBs <dd>An NxN block of samples for some value of N such that the division
of a component
into CTBs is a partitioning.</dd>
<dt>Coding tree unit (CTU):</dt>
<dd>A CTB of luma samples, two corresponding CTBs
of chroma samples of a picture that has three sample arrays, or a CTB of chroma samples of a picture that has three sample arrays, or a CTB
of samples of a monochrome picture or a picture that is coded using of samples of a monochrome picture or a picture that is coded using
three separate colour planes and syntax structures used to code the three separate colour planes and syntax structures used to code the
samples.</t> samples.</dd>
<dt>Coding Unit (CU):</dt>
<t>Decoding Capability Information (DCI): A syntax structure containing <dd>A coding block of luma samples, two corresponding coding
syntax elements that apply to the entire bitstream.</t> blocks of chroma samples of a picture that has three sample arrays in the
single tree mode, or a coding block of luma samples of a picture that has
<t>Decoded picture buffer (DPB): A buffer holding decoded pictures for three sample arrays in the dual tree mode, or two coding blocks of chroma
samples of a picture that has three sample arrays in the dual tree mode, or
a coding block of samples of a monochrome picture, and syntax structures
used to code the samples.</dd>
<dt>Decoding Capability Information (DCI):</dt>
<dd>A syntax structure containing
syntax elements that apply to the entire bitstream.</dd>
<dt>Decoded picture buffer (DPB):</dt>
<dd>A buffer holding decoded pictures for
reference, output reordering, or output delay specified for the reference, output reordering, or output delay specified for the
hypothetical reference decoder.</t> hypothetical reference decoder.</dd>
<dt>Gradual decoding refresh (GDR) picture:</dt>
<t>Gradual decoding refresh (GDR) picture: A picture for which each VCL NAL unit <dd>A picture for which each VCL NAL unit has nal_unit_type equal to G
has nal_unit_type equal to GDR_NUT.</t> DR_NUT.</dd>
<dt>Instantaneous decoding refresh (IDR) PU:</dt>
<t>Instantaneous decoding refresh (IDR) PU: A PU in which the coded picture <dd>A PU in which the coded picture
is an IDR picture.</t> is an IDR picture.</dd>
<dt>Instantaneous decoding refresh (IDR) picture:</dt>
<t>Instantaneous decoding refresh (IDR) picture: An IRAP picture for <dd>An IRAP picture for
which each VCL NAL unit has nal_unit_type equal to IDR_W_RADL or IDR_N_LP.</t> which each VCL NAL unit has nal_unit_type equal to IDR_W_RADL or IDR_N_LP.</dd>
<dt>Intra random access point (IRAP) AU:</dt>
<t>Intra random access point (IRAP) AU: An AU in which there is a PU <dd>An AU in which there is a PU
for each layer in the CVS and the coded picture in each PU is an for each layer in the CVS and the coded picture in each PU is an
IRAP picture.</t> IRAP picture.</dd>
<dt>Intra random access point (IRAP) PU:</dt>
<t>Intra random access point (IRAP) PU: A PU in which the coded picture <dd>A PU in which the coded picture
is an IRAP picture.</t> is an IRAP picture.</dd>
<dt>Intra random access point (IRAP) picture:</dt>
<t>Intra random access point (IRAP) picture: A coded picture for which all VCL N <dd>A coded picture for which all VCL NAL units have the same value of
AL units have the same value of nal_unit_type in the range of IDR_W_RADL to CRA_ nal_unit_type in the range of IDR_W_RADL to CRA_NUT, inclusive.</dd>
NUT, inclusive.</t> <dt>Layer:</dt>
<dd>A set of VCL NAL units that all have a particular value of
<t>Layer: A set of VCL NAL units that all have a particular value of nuh_layer_id and the associated non-VCL NAL units.</dd>
nuh_layer_id and the associated non-VCL NAL units.</t> <dt>Network abstraction layer (NAL) unit:</dt>
<dd>A syntax structure containing
<t>Network abstraction layer (NAL) unit: A syntax structure containing
an indication of the type of data to follow and bytes containing an indication of the type of data to follow and bytes containing
that data in the form of an RBSP interspersed as necessary with emulation that data in the form of an RBSP interspersed as necessary with emulation
prevention bytes.</t> prevention bytes.</dd>
<dt>Network abstraction layer (NAL) unit stream:</dt>
<t>Network abstraction layer (NAL) unit stream: A sequence of NAL units.</t> <dd>A sequence of NAL units.</dd>
<dt>Output Layer Set (OLS):</dt>
<t>Output Layer Set (OLS): A set of layers for which one or more layers are spec <dd>A set of layers for which one or more layers are specified as the
ified as the output layers.</t> output layers.</dd>
<dt>Operation point (OP):</dt>
<t>Operation point (OP): A temporal subset of an OLS, identified by an <dd>A temporal subset of an OLS, identified by an
OLS index and a highest value of TemporalId.</t> OLS index and a highest value of TemporalId.</dd>
<dt>Picture Header (PH):</dt>
<t>Picture parameter set (PPS): A syntax structure containing syntax <dd>A syntax structure containing syntax elements that
apply to all slices of a coded picture.</dd>
<dt>Picture parameter set (PPS):</dt>
<dd>A syntax structure containing syntax
elements that apply to zero or more entire coded pictures as determined elements that apply to zero or more entire coded pictures as determined
by a syntax element found in each slice header.</t> by a syntax element found in each slice header.</dd>
<dt>Picture unit (PU):</dt>
<t>Picture unit (PU): A set of NAL units that are associated with each <dd>A set of NAL units that are associated with each
other according to a specified classification rule, are consecutive other according to a specified classification rule, are consecutive
in decoding order, and contain exactly one coded picture.</t> in decoding order, and contain exactly one coded picture.</dd>
<dt>Random access:</dt>
<t>Random access: The act of starting the decoding process for a <dd>The act of starting the decoding process for a
bitstream at a point other than the beginning of the stream.</t> bitstream at a point other than the beginning of the bitstream.</dd>
<dt>Raw Byte Sequence Payload (RBSP):</dt>
<t>Sequence parameter set (SPS): A syntax structure containing syntax <dd>A syntax structure containing an integer
number of bytes that is encapsulated in a NAL unit and is either empty or
has the form of a string of data bits containing syntax elements followed
by an RBSP stop bit and zero or more subsequent bits equal to 0.</dd>
<dt>Sequence parameter set (SPS):</dt>
<dd>A syntax structure containing syntax
elements that apply to zero or more entire CLVSs as determined by elements that apply to zero or more entire CLVSs as determined by
the content of a syntax element found in the PPS referred to by a the content of a syntax element found in the PPS referred to by a
syntax element found in each picture header.</t> syntax element found in each picture header.</dd>
<dt>Slice:</dt>
<t>Slice: An integer number of complete tiles or an integer number of <dd>An integer number of complete tiles or an integer number of
consecutive complete CTU rows within a tile of a picture that are consecutive complete CTU rows within a tile of a picture that are
exclusively contained in a single NAL unit.</t> exclusively contained in a single NAL unit.</dd>
<dt>Slice header (SH):</dt>
<t>Slice header (SH): A part of a coded slice containing the data elements <dd>A part of a coded slice containing the data elements
pertaining to all tiles or CTU rows within a tile represented in the slice.</t> pertaining to all tiles or CTU rows within a tile represented in the slice.</dd>
<dt>Sublayer:</dt>
<t>Sublayer: A temporal scalable layer of a temporal scalable bitstream <dd>A temporal scalable layer of a temporal scalable bitstream
consisting of VCL NAL units with a particular value of the TemporalId consisting of VCL NAL units with a particular value of the TemporalId
variable, and the associated non-VCL NAL units.</t> variable, and the associated non-VCL NAL units.</dd>
<dt>Subpicture:</dt>
<t>Subpicture: An rectangular region of one or more slices within a picture.</t> <dd>A rectangular region of one or more slices within a picture.</dd>
<dt>Sublayer representation:</dt>
<t>Sublayer representation: A subset of the bitstream consisting of NAL <dd>A subset of the bitstream consisting of NAL
units of a particular sublayer and the lower sublayers.</t> units of a particular sublayer and the lower sublayers.</dd>
<dt>Tile:</dt>
<t>Tile: A rectangular region of CTUs within a particular tile column and <dd>A rectangular region of CTUs within a particular tile column and
a particular tile row in a picture.</t> a particular tile row in a picture.</dd>
<dt>Tile column:</dt>
<t>Tile column: A rectangular region of CTUs having a height equal to <dd>A rectangular region of CTUs having a height equal to
the height of the picture and a width specified by syntax elements in the height of the picture and a width specified by syntax elements in
the picture parameter set.</t> the picture parameter set.</dd>
<dt>Tile row:</dt>
<t>Tile row: A rectangular region of CTUs having a height specified by <dd>A rectangular region of CTUs having a height specified by
syntax elements in the picture parameter set and a width equal to the syntax elements in the picture parameter set and a width equal to the
width of the picture.</t> width of the picture.</dd>
<dt>Video coding layer (VCL) NAL unit:</dt>
<t>Video coding layer (VCL) NAL unit: A collective term for coded slice NAL <dd>A collective term for coded slice NAL
units and the subset of NAL units that have reserved values of units and the subset of NAL units that have reserved values of
nal_unit_type that are classified as VCL NAL units in this Specification.</t> nal_unit_type that are classified as VCL NAL units in this Specification.</dd>
</dl>
</section> </section>
<section anchor="def"><name>Definitions Specific to This Memo</name> <section anchor="def">
<name>Definitions Specific to This Memo</name>
<t>Media-Aware Network Element (MANE): A network element, such as a <dl newline="true" spacing="normal">
<dt>Media-Aware Network Element (MANE):</dt>
<dd><t>A network element, such as a
middlebox, selective forwarding unit, or application-layer gateway middlebox, selective forwarding unit, or application-layer gateway
that is capable of parsing certain aspects of the RTP payload headers that is capable of parsing certain aspects of the RTP payload headers
or the RTP payload and reacting to their contents.</t> or the RTP payload and reacting to their contents.</t>
<aside>
<ul empty="true"><li> <t>Informative note: The concept of a MANE goes beyond normal rout
<t>Informative note: The concept of a MANE goes beyond normal routers ers
or gateways in that a MANE has to be aware of the signaling (e.g., or gateways in that a MANE has to be aware of the signaling (e.g.,
to learn about the payload type mappings of the media streams), to learn about the payload type mappings of the media streams),
and in that it has to be trusted when working with Secure RTP and in that it has to be trusted when working with Secure RTP
(SRTP). The advantage of using MANEs is that they allow packets (SRTP). The advantage of using MANEs is that they allow packets
to be dropped according to the needs of the media coding. For to be dropped according to the needs of the media coding. For
example, if a MANE has to drop packets due to congestion on a example, if a MANE has to drop packets due to congestion on a
certain link, it can identify and remove those packets whose certain link, it can identify and remove those packets whose
elimination produces the least adverse effect on the user elimination produces the least adverse effect on the user
experience. After dropping packets, MANEs must rewrite RTCP experience. After dropping packets, MANEs must rewrite RTCP
packets to match the changes to the RTP stream, as specified in packets to match the changes to the RTP stream, as specified in
Section 7 of <xref target="RFC3550"/>.</t> <xref target="RFC3550" section="7" sectionFormat="of" />.</t></aside></dd>
</li></ul> <dt>NAL unit decoding order:</dt>
<dd>A NAL unit order that conforms to the
<t>NAL unit decoding order: A NAL unit order that conforms to the
constraints on NAL unit order given in Section 7.4.2.4 in <xref target="VVC"/>, constraints on NAL unit order given in Section 7.4.2.4 in <xref target="VVC"/>,
follow the Order of NAL units in the bitstream.</t> follow the order of NAL units in the bitstream.</dd>
<dt>RTP stream (see <xref target="RFC7656"/>):</dt>
<t>RTP stream (See <xref target="RFC7656"/>): Within the scope of this memo, on <dd>Within the scope of this memo, one RTP stream is utilized to tra
e RTP stream is utilized to transport a VVC bitstream, which may contain one or nsport a VVC bitstream, which may contain one or more layers, and each layer may
more layers, and each layer may contain one or more temporal sublayers.</t> contain one or more temporal sublayers.</dd>
<dt>Transmission order:</dt>
<t>Transmission order: The order of packets in ascending RTP sequence <dd>The order of packets in ascending RTP sequence
number order (in modulo arithmetic). Within an aggregation packet, number order (in modulo arithmetic). Within an aggregation packet,
the NAL unit transmission order is the same as the order of the NAL unit transmission order is the same as the order of
appearance of NAL units in the packet.</t> appearance of NAL units in the packet.</dd>
</dl>
</section> <!-- End of DNE -->
</section> </section>
<section anchor="abbreviations"><name>Abbreviations</name> </section>
<section anchor="abbreviations">
<t>AU         Access Unit</t> <name>Abbreviations</name>
<dl newline="false" spacing="normal" indent="8">
<t>AP         Aggregation Packet</t> <dt>AU</dt>
<dd>Access Unit</dd>
<t>APS        Adaptation Parameter Set</t> <dt>AP</dt>
<dd>Aggregation Packet</dd>
<t>CTU        Coding Tree Unit</t> <dt>APS</dt>
<dd>Adaptation Parameter Set</dd>
<t>CVS        Coded Video Sequence</t> <dt>CTU</dt>
<dd>Coding Tree Unit</dd>
<t>DPB        Decoded Picture Buffer</t> <dt>CVS</dt>
<dd>Coded Video Sequence</dd>
<t>DCI        Decoding Capability Information</t> <dt>DPB</dt>
<dd>Decoded Picture Buffer</dd>
<t>DON        Decoding Order Number</t> <dt>DCI</dt>
<dd>Decoding Capability Information</dd>
<t>FIR        Full Intra Request</t> <dt>DON</dt>
<dd>Decoding Order Number</dd>
<t>FU         Fragmentation Unit</t> <dt>FIR</dt>
<dd>Full Intra Request</dd>
<t>GDR        Gradual Decoding Refresh</t> <dt>FU</dt>
<dd>Fragmentation Unit</dd>
<t>HRD        Hypothetical Reference Decoder</t> <dt>GDR</dt>
<dd>Gradual Decoding Refresh</dd>
<t>IDR        Instantaneous Decoding Refresh</t> <dt>HRD</dt>
<dd>Hypothetical Reference Decoder</dd>
<t>IRAP       Intra Random Access Point</t> <dt>IDR</dt>
<dd>Instantaneous Decoding Refresh</dd>
<t>MANE       Media-Aware Network Element</t> <dt>IRAP</dt>
<dd>Intra Random Access Point</dd>
<t>MTU        Maximum Transfer Unit</t> <dt>MANE</dt>
<dd>Media-Aware Network Element</dd>
<t>NAL        Network Abstraction Layer</t> <dt>MTU</dt>
<dd>Maximum Transfer Unit</dd>
<t>NALU       Network Abstraction Layer Unit</t> <dt>NAL</dt>
<dd>Network Abstraction Layer</dd>
<t>OLS        Output Layer Set</t> <dt>NALU</dt>
<dd>Network Abstraction Layer Unit</dd>
<t>PLI        Picture Loss Indication</t> <dt>OLS</dt>
<dd>Output Layer Set</dd>
<t>PPS        Picture Parameter Set <dt>PLI</dt>
<dd>Picture Loss Indication</dd>
<dt>PPS</dt>
<dd>Picture Parameter Set</dd>
<!-- <!--
RPS &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Reference Picture Set --></t> RPS &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Reference Picture Set -->
<dt>RPSI</dt>
<t>RPSI       Reference Picture Selection Indication</t> <dd>Reference Picture Selection Indication</dd>
<dt>SEI</dt>
<t>SEI        Supplemental Enhancement Information</t> <dd>Supplemental Enhancement Information</dd>
<dt>SLI</dt>
<t>SLI        Slice Loss Indication</t> <dd>Slice Loss Indication</dd>
<dt>SPS</dt>
<t>SPS        Sequence Parameter Set</t> <dd>Sequence Parameter Set</dd>
<dt>VCL</dt>
<t>VCL        Video Coding Layer</t> <dd>Video Coding Layer</dd>
<dt>VPS</dt>
<t>VPS        Video Parameter Set</t> <dd>Video Parameter Set</dd>
</dl>
</section> </section>
</section> </section>
<section anchor="RTPPayloadFormat"><name>RTP Payload Format</name> <section anchor="RTPPayloadFormat">
<name>RTP Payload Format</name>
<section anchor="RTPHeaderUsage"><name>RTP Header Usage</name> <section anchor="RTPHeaderUsage">
<name>RTP Header Usage</name>
<t>The format of the RTP header is specified in <xref target="RFC3550"/> (reprin <t>The format of the RTP header is specified in <xref target="RFC3550"/>
ted as (reprinted as
<xref target="rtp-hdr"/> for convenience). This payload format uses the fields of <xref target="rtp-hdr"/> for convenience). This payload format uses the fields of
the header in a manner consistent with that specification.</t> the header in a manner consistent with that specification.</t>
<t>The RTP payload (and the settings for some RTP header bits) for
<t>The RTP payload (and the settings for some RTP header bits) for aggregation packets and fragmentation units are specified in Sections
aggregation packets and fragmentation units are specified in <xref target="aps" format="counter"/> and <xref target="funits" format="counter"
<xref target="aps"/> and <xref target="funits"/>, respectively.</t> />, respectively.</t>
<figure anchor="rtp-hdr">
<figure anchor="rtp-hdr"><sourcecode type="~"><![CDATA[ <name>RTP Header According to RFC 3550</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V=2|P|X| CC |M| PT | sequence number | |V=2|P|X| CC |M| PT | sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp | | timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| synchronization source (SSRC) identifier | | synchronization source (SSRC) identifier |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| contributing source (CSRC) identifiers | | contributing source (CSRC) identifiers |
| .... | | .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
RTP Header According to [RFC3550] </figure>
<t>The RTP header information to be set according to this RTP payload
]]></sourcecode></figure>
<t>The RTP header information to be set according to this RTP payload
format is set as follows:</t> format is set as follows:</t>
<dl newline="true" spacing="normal">
<t>Marker bit (M): 1 bit</t> <dt>Marker bit (M): 1 bit</dt>
<dd>Set for the last packet, in transmission order, among each set of
<ul empty="true"><li> packets that contain NAL units of one access unit. This is in line with the norm
<t>Set for the last packet, in transmission order, among each set of packets t al use of the M bit in
hat contain NAL units of one access unit. This is in line with the normal use of video formats to allow an efficient playout buffer handling.</dd>
the M bit in <dt>Payload Type (PT): 7 bits</dt>
video formats to allow an efficient playout buffer handling.</t> <dd>The assignment of an RTP payload type for this new packet format
</li></ul>
<t>Payload Type (PT): 7 bits</t>
<ul empty="true"><li>
<t>The assignment of an RTP payload type for this new packet format
is outside the scope of this document and will not be specified is outside the scope of this document and will not be specified
here. The assignment of a payload type has to be performed either here. The assignment of a payload type has to be performed either
through the profile used or in a dynamic way.</t> through the profile used or in a dynamic way.</dd>
</li></ul> <dt>Sequence Number (SN): 16 bits</dt>
<dd>Set and used in accordance with <xref target="RFC3550"/>.</dd>
<t>Sequence Number (SN): 16 bits</t> <dt>Timestamp: 32 bits</dt>
<dd><t>The RTP timestamp is set to the sampling timestamp of the conte
<ul empty="true"><li> nt. A 90 kHz clock rate <bcp14>MUST</bcp14> be used. If the NAL unit has no tim
<t>Set and used in accordance with <xref target="RFC3550"/>.</t> ing properties of its own (e.g., parameter set and SEI NAL units), the RTP times
</li></ul> tamp <bcp14>MUST</bcp14> be set to the RTP timestamp of the coded pictures of th
e access unit in which the NAL unit (according to Section 7.4.2.4 of <xref targe
<t>Timestamp: 32 bits</t> t="VVC" />) is included. Receivers <bcp14>MUST</bcp14> use the RTP timestamp for
the display process, even when the bitstream contains picture timing SEI messag
<ul empty="true"><li> es or decoding unit information SEI messages, as specified in <xref target="VVC"
<t>The RTP timestamp is set to the sampling timestamp of the content. A 90 kHz />.</t>
clock rate MUST be used. If the NAL unit has no timing properties of its own ( <aside><t>Informative note: When picture timing SEI messages are prese
e.g., parameter set and SEI NAL units), the RTP timestamp MUST be set to the RTP nt, the RTP sender is responsible to ensure that the RTP timestamps are consiste
timestamp of the coded pictures of the access unit in which the NAL unit (accor nt with the timing information carried in the picture timing SEI messages.</t></
ding to Section 7.4.2.4 of <xref target="VVC"/>) is included. Receivers MUST use aside>
the RTP timestamp for the display process, even when the bitstream contains pic </dd>
ture timing SEI messages or decoding unit information SEI messages as specified <dt>Synchronization source (SSRC): 32 bits</dt>
in <xref target="VVC"/>.</t> <dd>Used to identify the source of the RTP packets.
</li></ul> A single SSRC is used for all parts of a single bitstream.</dd>
</dl>
<ul empty="true"><li> </section>
<ul empty="true"><li> <section anchor="PayloadHeaderUsage">
<t>Informative note: When picture timing SEI messages are present, the RTP s <name>Payload Header Usage</name>
ender is responsible to ensure that the RTP timestamps are consistent with the t <t>The first two bytes of the payload of an RTP packet are referred to
iming information carried in the picture timing SEI messages.</t>
</li></ul>
</li></ul>
<t>Synchronization source (SSRC): 32 bits</t>
<ul empty="true"><li>
<t>Used to identify the source of the RTP packets.
A single SSRC is used for all parts of a single bitstream.</t>
</li></ul>
</section>
<section anchor="PayloadHeaderUsage"><name>Payload Header Usage</name>
<t>The first two bytes of the payload of an RTP packet are referred to
as the payload header. The payload header consists of the same as the payload header. The payload header consists of the same
fields (F, Z, LayerId, Type, and TID) as the NAL unit header as shown fields (F, Z, LayerId, Type, and TID) as the NAL unit header shown
in <xref target="NALUnitHeader"/>, irrespective of the type of the payload struc ture.</t> in <xref target="NALUnitHeader"/>, irrespective of the type of the payload struc ture.</t>
<t>The TID value indicates (among other things) the relative importance
<t>The TID value indicates (among other things) the relative importance
of an RTP packet, for example, because NAL units belonging to higher of an RTP packet, for example, because NAL units belonging to higher
temporal sublayers are not used for the decoding of lower temporal temporal sublayers are not used for the decoding of lower temporal
sublayers. A lower value of TID indicates a higher importance. sublayers. A lower value of TID indicates a higher importance.
More-important NAL units MAY be better protected against transmission More important NAL units <bcp14>MAY</bcp14> be better protected against transmis sion
losses than less-important NAL units.</t> losses than less-important NAL units.</t>
</section>
</section> <section anchor="PayloadStructures">
<section anchor="PayloadStructures"><name>Payload Structures</name> <name>Payload Structures</name>
<t>Three different types of RTP packet payload structures are specified.
<t>Three different types of RTP packet payload structures are specified.
A receiver can identify the type of an RTP packet payload through the A receiver can identify the type of an RTP packet payload through the
Type field in the payload header.</t> Type field in the payload header.</t>
<t>The three different payload structures are as follows:</t>
<t>The three different payload structures are as follows:</t> <ul spacing="normal">
<li>Single NAL unit packet: Contains a single NAL unit in the payload,
<t><list style="symbols">
<t>Single NAL unit packet: Contains a single NAL unit in the payload,
and the NAL unit header of the NAL unit also serves as the payload and the NAL unit header of the NAL unit also serves as the payload
header. This payload structure is specified in <xref target="SingleNALUnit"/>.< header. This payload structure is specified in <xref target="SingleNALUnit"/>.<
/t> /li>
<t>Aggregation Packet (AP): Contains more than one NAL unit within <li>Aggregation Packet (AP): Contains more than one NAL unit within
one access unit. This payload structure is specified in <xref target="aps"/>.</ one access unit. This payload structure is specified in <xref target="aps"/>.</
t> li>
<t>Fragmentation Unit (FU): Contains a subset of a single NAL unit. <li>Fragmentation Unit (FU): Contains a subset of a single NAL unit.
This payload structure is specified in <xref target="funits"/>.</t> This payload structure is specified in <xref target="funits"/>.</li>
</list></t> </ul>
<section anchor="SingleNALUnit">
<section anchor="SingleNALUnit"><name>Single NAL Unit Packets</name> <name>Single NAL Unit Packets</name>
<t>A single NAL unit packet contains exactly one NAL unit and consists
<t>A single NAL unit packet contains exactly one NAL unit, and consists of a payload header, as defined in Table 5 of <xref target="VVC"/> (denoted here
of a payload header as defined in Table 5 of <xref target="VVC"/> (denoted here as PayloadHdr),
as PayloadHdr), following with a conditional 16-bit DONL field (in network byte order), and the
following with a conditional 16-bit DONL field (in network byte order), and the NAL unit payload data
NAL unit payload data
(the NAL unit excluding its NAL unit header) of the contained NAL (the NAL unit excluding its NAL unit header) of the contained NAL
unit, as shown in <xref target="single-nhr"/>.</t> unit, as shown in <xref target="single-nhr"/>.</t>
<figure anchor="single-nhr">
<figure anchor="single-nhr"><artwork><![CDATA[ <name>The Structure of a Single NAL Unit Packet</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PayloadHdr | DONL (conditional) | | PayloadHdr | DONL (conditional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| NAL unit payload data | | NAL unit payload data |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
The Structure of a Single NAL Unit Packet </figure>
<t>The DONL field, when present, specifies the value of the 16 least s
]]></artwork></figure> ignificant bits of the decoding order number of the contained NAL
unit. If sprop-max-don-diff (defined in <xref target="optionalParameters"/>) is
<t>The DONL field, when present, specifies the value of the 16 least greater than 0, the DONL field <bcp14>MUST</bcp14> be present, and the variable
significant bits of the decoding order number of the contained NAL DON for the
unit. If sprop-max-don-diff (see definition in <xref target="optionalParameters
"/>) is greater than 0, the DONL field MUST be present, and the variable DON for
the
contained NAL unit is derived as equal to the value of the DONL contained NAL unit is derived as equal to the value of the DONL
field. Otherwise (sprop-max-don-diff is equal to 0), the DONL field MUST NOT be field. Otherwise (sprop-max-don-diff is equal to 0), the DONL field <bcp14>MUST
present.</t> NOT</bcp14> be present.</t>
</section>
</section> <section anchor="aps">
<section anchor="aps"><name>Aggregation Packets (APs)</name> <name>Aggregation Packets (APs)</name>
<t>Aggregation packets (APs) can reduce
<t>Aggregation Packets (APs) can reduce
packetization overhead for small NAL units, such as most of the non-VCL NAL unit s, which are often only a few octets in size.</t> packetization overhead for small NAL units, such as most of the non-VCL NAL unit s, which are often only a few octets in size.</t>
<t>An AP aggregates NAL units of one access unit, and it <bcp14>MUST N
<t>An AP aggregates NAL units of one access unit and it MUST NOT contain NAL uni OT</bcp14> contain NAL units from more than one AU. Each NAL unit to be carried
ts from more than one AU. Each NAL unit to be carried in an AP is encapsulated i in an AP is encapsulated in an aggregation unit. NAL units aggregated in one AP
n an aggregation unit. NAL units aggregated in one AP are included in NAL unit are included in NAL-unit-decoding order.</t>
decoding order.</t> <t>An AP consists of a payload header, as defined in Table 5 of <xref
target="VVC"/> (denoted here as PayloadHdr with Type=28), followed by two or mor
<t>An AP consists of a payload header as defined in Table 5 of <xref target="VVC e aggregation units, as shown in <xref target="au-hdr"/>.</t>
"/> (denoted here as PayloadHdr with Type=28) followed by two or more aggregatio <figure anchor="au-hdr">
n units, as shown in <xref target="au-hdr"/>.</t> <name>The Structure of an Aggregation Packet</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
<figure anchor="au-hdr"><artwork><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PayloadHdr (Type=28) | | | PayloadHdr (Type=28) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| two or more aggregation units | | two or more aggregation units |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
The Structure of an Aggregation Packet </figure>
<t>The fields in the payload header of an AP are set as follows. The
]]></artwork></figure> F bit <bcp14>MUST</bcp14>
<t>The fields in the payload header of an AP are set as follows. The F bit MUST
be equal to 0 if the F bit of each aggregated NAL unit is equal to be equal to 0 if the F bit of each aggregated NAL unit is equal to
zero; otherwise, it MUST be equal to 1. The Type field MUST be equal zero; otherwise, it <bcp14>MUST</bcp14> be equal to 1. The Type field <bcp14>MU ST</bcp14> be equal
to 28.</t> to 28.</t>
<t>The value of LayerId <bcp14>MUST</bcp14> be equal to the lowest val
<t>The value of LayerId MUST be equal to the lowest value of LayerId of ue of LayerId of
all the aggregated NAL units. The value of TID MUST be the lowest all the aggregated NAL units. The value of TID <bcp14>MUST</bcp14> be the lowes
t
value of TID of all the aggregated NAL units.</t> value of TID of all the aggregated NAL units.</t>
<aside><t>Informative note: All VCL NAL units in an AP have the sa
<ul empty="true"><li> me TID
<t>Informative note: All VCL NAL units in an AP have the same TID
value since they belong to the same access unit. However, an AP value since they belong to the same access unit. However, an AP
may contain non-VCL NAL units for which the TID value in the NAL may contain non-VCL NAL units for which the TID value in the NAL
unit header may be different than the TID value of the VCL NAL unit header may be different than the TID value of the VCL NAL
units in the same AP.</t> units in the same AP.</t></aside>
</li></ul> <aside><t>Informative note: If a system envisions subpicture-level
or picture-level modifications, for example, by removing subpictures or picture
<ul empty="true"><li> s of a particular layer, a good design choice on the sender's side would be to a
<t>Informative Note: If a system envisions sub-picture level or picture level ggregate NAL units belonging to only the same subpicture or picture of a particu
modifications, for example by removing sub-pictures or pictures of a particular lar layer.</t></aside>
layer, a good design choice on the sender’s side would be to aggregate NAL units <t>An AP <bcp14>MUST</bcp14> carry at least two aggregation units and
belonging to only the same sub-picture or picture of a particular layer.</t> can carry as many
</li></ul>
<t>An AP MUST carry at least two aggregation units and can carry as many
aggregation units as necessary; however, the total amount of data in aggregation units as necessary; however, the total amount of data in
an AP obviously MUST fit into an IP packet, and the size SHOULD be an AP obviously <bcp14>MUST</bcp14> fit into an IP packet, and the size <bcp14>S HOULD</bcp14> be
chosen so that the resulting IP packet is smaller than the MTU size chosen so that the resulting IP packet is smaller than the MTU size
so to avoid IP layer fragmentation. An AP MUST NOT contain FUs in order to avoid IP layer fragmentation. An AP <bcp14>MUST NOT</bcp14> contain
specified in <xref target="funits"/>. APs MUST NOT be nested; i.e., an AP can the FUs
not contain another AP.</t> specified in <xref target="funits"/>. APs <bcp14>MUST NOT</bcp14> be nested, i.
e., an AP cannot contain another AP.</t>
<t>The first aggregation unit in an AP consists of a conditional 16-bit <t>The first aggregation unit in an AP consists of a conditional 16-bi
DONL field (in network byte order) followed by a 16-bit unsigned size t
information (in network byte order) that indicates the size of the DONL field (in network byte order), followed by 16 bits of unsigned size
NAL unit in bytes (excluding these two octets, but including the NAL information (in network byte order) that indicate the size of the
NAL unit in bytes (excluding these two octets but including the NAL
unit header), followed by the NAL unit itself, including its NAL unit unit header), followed by the NAL unit itself, including its NAL unit
header, as shown in <xref target="au-first-nhdr"/>.</t> header, as shown in <xref target="au-first-nhdr"/>.</t>
<figure anchor="au-first-nhdr">
<figure anchor="au-first-nhdr"><artwork><![CDATA[ <name>The Structure of the First Aggregation Unit in an AP</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : DONL (conditional) | NALU size | | : DONL (conditional) | NALU size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU size | | | NALU size | |
+-+-+-+-+-+-+-+-+ NAL unit | +-+-+-+-+-+-+-+-+ NAL unit |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : | :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
The Structure of the First Aggregation Unit in an AP </figure>
<aside><t>Informative note: The first octet of <xref target="au-fi
]]></artwork></figure> rst-nhdr"/> (indicated by the first colon) belongs to a previous aggregation uni
t. It is depicted to emphasize that aggregation units are octet aligned only. Si
<ul empty="true"><li> milarly, the NAL unit carried in the aggregation unit can terminate at the octet
<t>Informative Note: The first octet of <xref target="au-first-nhdr"/> (indica boundary.</t></aside>
ted by the first colon) belongs to a previous aggregation unit. It is depicted t <t>The DONL field, when present, specifies the value of the 16 least s
o emphasize that aggregation units are octet-aligned only. Similarly, the NAL un ignificant bits of the decoding order number of the aggregated NAL
it carried in the aggregation unit can terminate at the octet boundary.</t>
</li></ul>
<t>The DONL field, when present, specifies the value of the 16 least
significant bits of the decoding order number of the aggregated NAL
unit.</t> unit.</t>
<t>If sprop-max-don-diff is greater than 0, the DONL field <bcp14>MUST
<t>If sprop-max-don-diff is greater than 0, the DONL field MUST be present in an </bcp14> be present in an aggregation unit that is the first aggregation unit in
aggregation unit that is the first aggregation unit in an AP, and the variable an AP, and the variable DON for the aggregated NAL unit is derived as equal to
DON for the aggregated NAL unit is derived as equal to the value of the DONL fie the value of the DONL field, and the variable DON for an aggregation unit that i
ld, and the variable DON for an aggregation unit that is not the first aggregati s not the first aggregation unit in an AP-aggregated NAL unit is derived as equa
on unit in an AP aggregated NAL unit is derived as equal to the DON of the prece l to the DON of the preceding aggregated NAL unit in the same AP plus 1 modulo 6
ding aggregated NAL unit in the same AP plus 1 modulo 65536. Otherwise (sprop-ma 5536. Otherwise (sprop-max-don-diff is equal to 0), the DONL field <bcp14>MUST N
x-don-diff is equal to 0), the DONL field MUST NOT be present in an aggregation OT</bcp14> be present in an aggregation unit that is the first aggregation unit
unit that is the first aggregation unit in an AP.</t> in an AP.</t>
<t>An aggregation unit that is not the first aggregation unit in an AP
<t>An aggregation unit that is not the first aggregation unit in an AP will be followed immediately by 16 bits of unsigned size information
will be followed immediately by a 16-bit unsigned size information (in network byte order) that indicate the
(in network byte order) that indicates the size of the NAL unit in bytes (excluding these two octets but
size of the NAL unit in bytes (excluding these two octets, but
including the NAL unit header), followed by the NAL unit itself, including the NAL unit header), followed by the NAL unit itself,
including its NAL unit header, as shown in <xref target="au-not-first-nhdr"/>.</ t> including its NAL unit header, as shown in <xref target="au-not-first-nhdr"/>.</ t>
<figure anchor="au-not-first-nhdr">
<figure anchor="au-not-first-nhdr"><artwork><![CDATA[ <name>The Structure of an Aggregation Unit That Is Not the First Aggr
egation Unit in an AP</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : NALU size | NAL unit | | : NALU size | NAL unit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : | :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
The Structure of an Aggregation Unit That Is Not the First </figure>
Aggregation Unit in an AP <aside><t>Informative note: The first octet of <xref target="au-not-fi
rst-nhdr"/> (indicated by the first colon) belongs to a previous aggregation uni
]]></artwork></figure> t. It is depicted to emphasize that aggregation units are octet aligned only. Si
milarly, the NAL unit carried in the aggregation unit can terminate at the octet
<ul empty="true"><li> boundary.</t></aside>
<t>Informative Note: The first octet of <xref target="au-not-first-nhdr"/> (in <t><xref target="au-wout-donl"/> presents an example of an AP that con
dicated by the first colon) belongs to a previous aggregation unit. It is depict tains two aggregation
ed to emphasize that aggregation units are octet-aligned only. Similarly, the NA
L unit carried in the aggregation unit can terminate at the octet boundary.</t>
</li></ul>
<t><xref target="au-wout-donl"/> presents an example of an AP that contains two
aggregation
units, labeled as 1 and 2 in the figure, without the DONL field units, labeled as 1 and 2 in the figure, without the DONL field
being present.</t> being present.</t>
<figure anchor="au-wout-donl">
<figure anchor="au-wout-donl"><artwork><![CDATA[ <name>An Example of an AP Packet Containing Two Aggregation Units wit
hout the DONL Field</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Header | | RTP Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PayloadHdr (Type=28) | NALU 1 Size | | PayloadHdr (Type=28) | NALU 1 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 1 HDR | | | NALU 1 HDR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 1 Data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 1 Data |
| . . . | | . . . |
| | | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . | NALU 2 Size | NALU 2 HDR | | . . . | NALU 2 Size | NALU 2 HDR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 2 HDR | | | NALU 2 HDR | |
+-+-+-+-+-+-+-+-+ NALU 2 Data | +-+-+-+-+-+-+-+-+ NALU 2 Data |
| . . . | | . . . |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
An Example of an AP Packet Containing </figure>
Two Aggregation Units without the DONL Field <t><xref target="au-with-donl"/> presents an example of an AP that con
tains two aggregation
]]></artwork></figure>
<t><xref target="au-with-donl"/> presents an example of an AP that contains two
aggregation
units, labeled as 1 and 2 in the figure, with the DONL field being present.</t> units, labeled as 1 and 2 in the figure, with the DONL field being present.</t>
<figure anchor="au-with-donl">
<figure anchor="au-with-donl"><artwork><![CDATA[ <name>An Example of an AP Containing Two Aggregation Units with the D
ONL Field</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Header | | RTP Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PayloadHdr (Type=28) | NALU 1 DONL | | PayloadHdr (Type=28) | NALU 1 DONL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 1 Size | NALU 1 HDR | | NALU 1 Size | NALU 1 HDR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
skipping to change at line 1034 skipping to change at line 884
| | | |
+ . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : NALU 2 Size | | : NALU 2 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 2 HDR | | | NALU 2 HDR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 2 Data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 2 Data |
| | | |
| . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
An Example of an AP Containing </figure>
Two Aggregation Units with the DONL Field </section>
<section anchor="funits">
]]></artwork></figure> <name>Fragmentation Units</name>
<t>Fragmentation Units (FUs) are introduced to enable fragmenting a
</section>
<section anchor="funits"><name>Fragmentation Units</name>
<t>Fragmentation Units (FUs) are introduced to enable fragmenting a
single NAL unit into multiple RTP packets, possibly without single NAL unit into multiple RTP packets, possibly without
cooperation or knowledge of the <xref target="VVC"/> encoder. A fragment cooperation or knowledge of the <xref target="VVC"/> encoder. A fragment
of a NAL unit consists of an integer number of consecutive octets of of a NAL unit consists of an integer number of consecutive octets of
that NAL unit. Fragments of the same NAL unit MUST be sent in that NAL unit. Fragments of the same NAL unit <bcp14>MUST</bcp14> be sent in
consecutive order with ascending RTP sequence numbers (with no other consecutive order with ascending RTP sequence numbers (with no other
RTP packets within the same RTP stream being sent between the first RTP packets within the same RTP stream being sent between the first
and last fragment).</t> and last fragment).</t>
<t>When a NAL unit is fragmented and conveyed within FUs, it is referr
<t>When a NAL unit is fragmented and conveyed within FUs, it is referred ed
to as a fragmented NAL unit. APs MUST NOT be fragmented. FUs MUST to as a fragmented NAL unit. APs <bcp14>MUST NOT</bcp14> be fragmented. FUs <b
NOT be nested; i.e., an FU can not contain a subset of another FU.</t> cp14>MUST
NOT</bcp14> be nested, i.e., an FU cannot contain a subset of another FU.</t>
<t>The RTP timestamp of an RTP packet carrying an FU is set to the NALU- <t>The RTP timestamp of an RTP packet carrying an FU is set to the NAL
U-
time of the fragmented NAL unit.</t> time of the fragmented NAL unit.</t>
<t>An FU consists of a payload header as defined in Table 5 of <xref t
<t>An FU consists of a payload header as defined in Table 5 of <xref target="VVC arget="VVC"/> (denoted here as PayloadHdr with Type=29), an FU header of one oct
"/> (denoted here as PayloadHdr with Type=29), an FU header of one octet, a cond et, a conditional 16-bit DONL field (in network byte order), and an FU payload (
itional 16-bit DONL field (in network byte order), and an FU payload, as shown i as shown in <xref target="fu-payload"/>).</t>
n <xref target="fu-payload"/>.</t> <figure anchor="fu-payload">
<name> The Structure of an FU</name>
<figure anchor="fu-payload"><artwork><![CDATA[ <artwork name="" type="" align="left" alt=""><![CDATA[
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PayloadHdr (Type=29) | FU header | DONL (cond) | | PayloadHdr (Type=29) | FU header | DONL (cond) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| DONL (cond) | | | DONL (cond) | |
|-+-+-+-+-+-+-+-+ | |-+-+-+-+-+-+-+-+ |
| FU payload | | FU payload |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
The Structure of an FU </figure>
<t>The fields in the payload header are set as follows. The Type fiel
]]></artwork></figure> d
<bcp14>MUST</bcp14> be equal to 29. The fields F, LayerId, and TID <bcp14>MUST<
<t>The fields in the payload header are set as follows. The Type field /bcp14> be equal to
MUST be equal to 29. The fields F, LayerId, and TID MUST be equal to
the fields F, LayerId, and TID, respectively, of the fragmented NAL the fields F, LayerId, and TID, respectively, of the fragmented NAL
unit.</t> unit.</t>
<t>The FU header consists of an S bit, an E bit, an R bit, and a 5-bit
<t>The FU header consists of an S bit, an E bit, an R bit and a 5-bit FuType FuType
field, as shown in <xref target="fu-hdr"/>.</t> field, as shown in <xref target="fu-hdr"/>.</t>
<figure anchor="fu-hdr">
<figure anchor="fu-hdr"><artwork><![CDATA[ <name>The Structure of the FU Header</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
+---------------+ +---------------+
|0|1|2|3|4|5|6|7| |0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|S|E|P| FuType | |S|E|P| FuType |
+---------------+ +---------------+
]]></artwork>
The Structure of FU Header </figure>
<t>The semantics of the FU header fields are as follows:</t>
]]></artwork></figure> <dl newline="true" spacing="normal">
<dt>S: 1 bit</dt>
<t>The semantics of the FU header fields are as follows:</t> <dd>When set to 1, the S bit indicates the start of a fragmented NAL
<t>S: 1 bit</t>
<ul empty="true"><li>
<t>When set to 1, the S bit indicates the start of a fragmented NAL
unit, i.e., the first byte of the FU payload is also the first unit, i.e., the first byte of the FU payload is also the first
byte of the payload of the fragmented NAL unit. When the FU byte of the payload of the fragmented NAL unit. When the FU
payload is not the start of the fragmented NAL unit payload, the S payload is not the start of the fragmented NAL unit payload, the S
bit MUST be set to 0.</t> bit <bcp14>MUST</bcp14> be set to 0.</dd>
</li></ul> <dt>E: 1 bit</dt>
<dd>When set to 1, the E bit indicates the end of a fragmented NAL
<ul empty="true"><li>
</li></ul>
<t>E: 1 bit</t>
<ul empty="true"><li>
<t>When set to 1, the E bit indicates the end of a fragmented NAL
unit, i.e., the last byte of the payload is also the last byte of unit, i.e., the last byte of the payload is also the last byte of
the fragmented NAL unit. When the FU payload is not the last the fragmented NAL unit. When the FU payload is not the last
fragment of a fragmented NAL unit, the E bit MUST be set to 0.</t> fragment of a fragmented NAL unit, the E bit <bcp14>MUST</bcp14> be set to 0.</d
</li></ul> d>
<dt>P: 1 bit</dt>
<t>P: 1 bit</t> <dd>When set to 1, the P bit indicates the last FU of the last VCL N
AL unit of a coded picture, i.e., the last byte of the FU payload is also the la
<ul empty="true"><li> st byte of the last VCL NAL unit of the coded picture. When the FU payload is n
<t>When set to 1, the P bit indicates the last FU of the last VCL NAL unit of ot the last fragment of the last VCL NAL unit of a coded picture, the P bit <bcp
a coded picture, i.e., the last byte of the FU payload is also the last byte of 14>MUST</bcp14> be set to 0.</dd>
the last VCL NAL unit of the coded picture. When the FU payload is not the last <dt>FuType: 5 bits</dt>
fragment of the last VCL NAL unit of a coded picture, the P bit MUST be set to <dd>The field FuType <bcp14>MUST</bcp14> be equal to the field Type
0.</t> of the fragmented
</li></ul> NAL unit.</dd>
</dl>
<t>FuType: 5 bits</t> <t>The DONL field, when present, specifies the value of the 16 least s
ignificant bits of the decoding order number of the fragmented NAL
<ul empty="true"><li>
<t>The field FuType MUST be equal to the field Type of the fragmented
NAL unit.</t>
</li></ul>
<t>The DONL field, when present, specifies the value of the 16 least
significant bits of the decoding order number of the fragmented NAL
unit.</t> unit.</t>
<t>If sprop-max-don-diff is greater than 0,
<t>If sprop-max-don-diff is greater than 0, and the S bit is equal to 1, the DONL field <bcp14>MUST</bcp14> be present in th
and the S bit is equal to 1, the DONL field MUST be present in the e
FU, and the variable DON for the fragmented NAL unit is derived as FU, and the variable DON for the fragmented NAL unit is derived as
equal to the value of the DONL field. Otherwise (sprop-max-don-diff equal to the value of the DONL field. Otherwise (sprop-max-don-diff
is equal to 0, or the S bit is equal to 0), is equal to 0, or the S bit is equal to 0),
the DONL field MUST NOT be present in the FU.</t> the DONL field <bcp14>MUST NOT</bcp14> be present in the FU.</t>
<t>A non-fragmented NAL unit <bcp14>MUST NOT</bcp14> be transmitted in
<t>A non-fragmented NAL unit MUST NOT be transmitted in one FU; i.e., one FU, i.e.,
the Start bit and End bit must not both be set to 1 in the same FU the Start bit and End bit must not both be set to 1 in the same FU
header.</t> header.</t>
<t>The FU payload consists of fragments of the payload of the fragment
<t>The FU payload consists of fragments of the payload of the fragmented ed
NAL unit so that if the FU payloads of consecutive FUs, starting with NAL unit so that, if the FU payloads of consecutive FUs, starting with
an FU with the S bit equal to 1 and ending with an FU with the E bit an FU with the S bit equal to 1 and ending with an FU with the E bit
equal to 1, are sequentially concatenated, the payload of the equal to 1, are sequentially concatenated, the payload of the
fragmented NAL unit can be reconstructed. The NAL unit header of the fragmented NAL unit can be reconstructed. The NAL unit header of the
fragmented NAL unit is not included as such in the FU payload, but fragmented NAL unit is not included as such in the FU payload, but
rather the information of the NAL unit header of the fragmented NAL rather the information of the NAL unit header of the fragmented NAL
unit is conveyed in F, LayerId, and TID fields of the FU payload unit is conveyed in the F, LayerId, and TID fields of the FU payload
headers of the FUs and the FuType field of the FU header of the FUs. headers of the FUs and the FuType field of the FU header of the FUs.
An FU payload MUST NOT be empty.</t> An FU payload <bcp14>MUST NOT</bcp14> be empty.</t>
<t>If an FU is lost, the receiver <bcp14>SHOULD</bcp14> discard all fo
<t>If an FU is lost, the receiver SHOULD discard all following llowing
fragmentation units in transmission order corresponding to the same fragmentation units in transmission order, corresponding to the same
fragmented NAL unit, unless the decoder in the receiver is known to fragmented NAL unit, unless the decoder in the receiver is known to
be prepared to gracefully handle incomplete NAL units.</t> be prepared to gracefully handle incomplete NAL units.</t>
<t>A receiver in an endpoint or in a MANE <bcp14>MAY</bcp14> aggregate
<t>A receiver in an endpoint or in a MANE MAY aggregate the first n-1 the first n-1
fragments of a NAL unit to an (incomplete) NAL unit, even if fragment fragments of a NAL unit to an (incomplete) NAL unit, even if fragment
n of that NAL unit is not received. In this case, the n of that NAL unit is not received. In this case, the
forbidden_zero_bit of the NAL unit MUST be set to 1 to indicate a forbidden_zero_bit of the NAL unit <bcp14>MUST</bcp14> be set to 1 to indicate a
syntax violation.</t> syntax violation.</t>
</section>
</section> </section>
</section> <section anchor="DON">
<section anchor="DON"><name>Decoding Order Number</name> <name>Decoding Order Number</name>
<t>For each NAL unit, the variable AbsDon is derived, representing the
<t>For each NAL unit, the variable AbsDon is derived, representing the
decoding order number that is indicative of the NAL unit decoding decoding order number that is indicative of the NAL unit decoding
order.</t> order.</t>
<t>Let NAL unit n be the n-th NAL unit in transmission order within an
<t>Let NAL unit n be the n-th NAL unit in transmission order within an
RTP stream.</t> RTP stream.</t>
<t>If sprop-max-don-diff is equal to 0, AbsDon[n], the value of AbsDon f
<t>If sprop-max-don-diff is equal to 0, AbsDon[n], the value of AbsDon for NAL u or NAL unit n, is derived as equal to n.</t>
nit n, is derived as equal to n.</t> <t>Otherwise (sprop-max-don-diff is greater than 0), AbsDon[n] is derive
d as follows, where DON[n] is the value
<t>Otherwise (sprop-max-don-diff is greater than 0), AbsDon[n] is derived as fol
lows, where DON[n] is the value
of the variable DON for NAL unit n:</t> of the variable DON for NAL unit n:</t>
<ul spacing="normal">
<t><list style="symbols"> <li>If n is equal to 0 (i.e., NAL unit n is the very first NAL unit
<t>If n is equal to 0 (i.e., NAL unit n is the very first NAL unit in transmission order), AbsDon[0] is set equal to DON[0].</li>
in transmission order), AbsDon[0] is set equal to DON[0].</t> <li>Otherwise (n is greater than 0), the following applies for
<t>Otherwise (n is greater than 0), the following applies for derivation of AbsDon[n]:</li>
derivation of AbsDon[n]:</t> </ul>
</list></t> <artwork name="" type="" align="left" alt=""><![CDATA[
<figure><artwork><![CDATA[
If DON[n] == DON[n-1], If DON[n] == DON[n-1],
AbsDon[n] = AbsDon[n-1] AbsDon[n] = AbsDon[n-1]
If (DON[n] > DON[n-1] and DON[n] - DON[n-1] < 32768), If (DON[n] > DON[n-1] and DON[n] - DON[n-1] < 32768),
AbsDon[n] = AbsDon[n-1] + DON[n] - DON[n-1] AbsDon[n] = AbsDon[n-1] + DON[n] - DON[n-1]
If (DON[n] < DON[n-1] and DON[n-1] - DON[n] >= 32768), If (DON[n] < DON[n-1] and DON[n-1] - DON[n] >= 32768),
AbsDon[n] = AbsDon[n-1] + 65536 - DON[n-1] + DON[n] AbsDon[n] = AbsDon[n-1] + 65536 - DON[n-1] + DON[n]
If (DON[n] > DON[n-1] and DON[n] - DON[n-1] >= 32768), If (DON[n] > DON[n-1] and DON[n] - DON[n-1] >= 32768),
AbsDon[n] = AbsDon[n-1] - (DON[n-1] + 65536 - DON[n]) AbsDon[n] = AbsDon[n-1] - (DON[n-1] + 65536 - DON[n])
If (DON[n] < DON[n-1] and DON[n-1] - DON[n] < 32768), If (DON[n] < DON[n-1] and DON[n-1] - DON[n] < 32768),
AbsDon[n] = AbsDon[n-1] - (DON[n-1] - DON[n]) AbsDon[n] = AbsDon[n-1] - (DON[n-1] - DON[n])
]]></artwork></figure> ]]></artwork>
<t>For any two NAL units (m and n), the following applies:</t>
<t>For any two NAL units m and n, the following applies:</t> <ul spacing="normal">
<li>When AbsDon[n] is greater than AbsDon[m], this indicates that NAL
<t><list style="symbols"> unit n follows NAL unit m in NAL unit decoding order.</li>
<t>AbsDon[n] greater than AbsDon[m] indicates that NAL unit n follows NAL unit <li>When AbsDon[n] is equal to AbsDon[m], the NAL unit decoding order
m in NAL unit decoding order.</t> of the two NAL units can be in either order.</li>
<t>When AbsDon[n] is equal to AbsDon[m], the NAL unit decoding order of the tw <li>When AbsDon[n] is less than AbsDon[m], this indicates that NAL uni
o NAL units can be in either order.</t> t n precedes NAL unit m in decoding order.</li>
<t>AbsDon[n] less than AbsDon[m] indicates that NAL unit n precedes NAL unit m </ul>
in decoding order.</t> <aside><t>Informative note: When two consecutive NAL units in the NAL
</list></t>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: When two consecutive NAL units in the NAL
unit decoding order have different values of AbsDon, the unit decoding order have different values of AbsDon, the
absolute difference between the two AbsDon values may be absolute difference between the two AbsDon values may be
greater than or equal to 1.</t> greater than or equal to 1.</t></aside>
</li></ul> <aside><t>Informative note: There are multiple reasons to allow for
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: There are multiple reasons to allow for
the absolute difference of the values of AbsDon for two the absolute difference of the values of AbsDon for two
consecutive NAL units in the NAL unit decoding order to consecutive NAL units in the NAL unit decoding order to
be greater than one. An increment by one is not required, be greater than one. An increment by one is not required, as at the time of
as at the time of associating values of AbsDon to NAL units, associating values of AbsDon to NAL units,
it may not be known whether all NAL units are to be it may not be known whether all NAL units are to be
delivered to the receiver. For example, a gateway might delivered to the receiver. For example, a gateway might
not forward VCL NAL units of higher sublayers or some not forward VCL NAL units of higher sublayers or some
SEI NAL units when there is congestion in the network. In another example, the f irst intra-coded picture of a pre-encoded clip is transmitted in advance to ensu re that it is readily available in the receiver, and when transmitting the first intra-coded picture, the originator SEI NAL units when there is congestion in the network. In another example, the f irst intra-coded picture of a pre-encoded clip is transmitted in advance to ensu re that it is readily available in the receiver, and when transmitting the first intra-coded picture, the originator
does not exactly know how many NAL units will be encoded does not exactly know how many NAL units will be encoded
before the first intra-coded picture of the pre-encoded before the first intra-coded picture of the pre-encoded
clip follows in decoding order. Thus, the values of clip follows in decoding order. Thus, the values of
AbsDon for the NAL units of the first intra-coded picture AbsDon for the NAL units of the first intra-coded picture
of the pre-encoded clip have to be estimated when of the pre-encoded clip have to be estimated when
they are transmitted, and gaps in values of AbsDon may occur.</t> they are transmitted, and gaps in values of AbsDon may occur.</t></aside>
</li></ul> </section>
</li></ul> </section>
<section anchor="PacketizationRules">
</section> <name>Packetization Rules</name>
</section> <t>The following packetization rules apply:</t>
<section anchor="PacketizationRules"><name>Packetization Rules</name> <ul spacing="normal">
<li>If sprop-max-don-diff is greater than 0, the transmission order of N
<t>The following packetization rules apply:</t> AL units carried in the RTP
stream <bcp14>MAY</bcp14> be different than the NAL unit decoding order. Otherwi
<t><list style="symbols"> se (sprop-max-don-diff is equal to 0), the transmission order of NAL units carri
<t>If sprop-max-don-diff is greater than 0, the transmission order of NAL unit ed in the RTP stream <bcp14>MUST</bcp14> be the same as the NAL unit decoding or
s carried in the RTP der.</li>
stream MAY be different than the NAL unit decoding order. Otherwise (sprop-max-d <li>A NAL unit of a small size <bcp14>SHOULD</bcp14> be encapsulated in
on-diff is equal to 0), the transmission order of NAL units carried in the RTP s an
tream MUST be the same as the NAL unit decoding order.</t>
<t>A NAL unit of a small size SHOULD be encapsulated in an
aggregation packet together with one or more other NAL units in aggregation packet together with one or more other NAL units in
order to avoid the unnecessary packetization overhead for small order to avoid the unnecessary packetization overhead for small
NAL units. For example, non-VCL NAL units such as access unit NAL units. For example, non-VCL NAL units, such as access unit
delimiters, parameter sets, or SEI NAL units are typically small delimiters, parameter sets, or SEI NAL units, are typically small
and can often be aggregated with VCL NAL units without violating and can often be aggregated with VCL NAL units without violating
MTU size constraints.</t> MTU size constraints.</li>
<t>Each non-VCL NAL unit SHOULD, when possible from an MTU size match <li>Each non-VCL NAL unit <bcp14>SHOULD</bcp14>, when possible from an M
TU size match
viewpoint, be encapsulated in an aggregation packet together with viewpoint, be encapsulated in an aggregation packet together with
its associated VCL NAL unit, as typically a non-VCL NAL unit would its associated VCL NAL unit, as typically a non-VCL NAL unit would
be meaningless without the associated VCL NAL unit being be meaningless without the associated VCL NAL unit being
available.</t> available.</li>
<t>For carrying exactly one NAL unit in an RTP packet, a single NAL <li>For carrying exactly one NAL unit in an RTP packet, a single NAL
unit packet MUST be used.</t> unit packet <bcp14>MUST</bcp14> be used.</li>
</list></t> </ul>
</section>
</section> <section anchor="DepacketizationProcess">
<section anchor="DepacketizationProcess"><name>De-packetization Process</name> <name>De-packetization Process</name>
<t>The general concept behind de-packetization is to get the NAL units
<t>The general concept behind de-packetization is to get the NAL units
out of the RTP packets in an RTP stream and pass them to the decoder in the NAL out of the RTP packets in an RTP stream and pass them to the decoder in the NAL
unit decoding order.</t> unit decoding order.</t>
<t>The de-packetization process is implementation dependent. Therefore,
<t>The de-packetization process is implementation dependent. Therefore,
the following description should be seen as an example of a suitable the following description should be seen as an example of a suitable
implementation. Other schemes may be used as well, as long as the implementation. Other schemes may be used as well, as long as the
output for the same input is the same as the process described below. output for the same input is the same as the process described below.
The output is the same when the set of output NAL units and their The output is the same when the set of output NAL units and their
order are both identical. Optimizations relative to the described order are both identical. Optimizations relative to the described
algorithms are possible.</t> algorithms are possible.</t>
<t>All normal RTP mechanisms related to buffer management apply. In
<t>All normal RTP mechanisms related to buffer management apply. In
particular, duplicated or outdated RTP packets (as indicated by the particular, duplicated or outdated RTP packets (as indicated by the
RTP sequence number and the RTP timestamp) are removed. To RTP sequence number and the RTP timestamp) are removed. To
determine the exact time for decoding, factors such as a possible determine the exact time for decoding, factors, such as a possible
intentional delay to allow for proper inter-stream synchronization intentional delay to allow for proper inter-stream synchronization,
MUST be factored in.</t> <bcp14>MUST</bcp14> be factored in.</t>
<t>NAL units with NAL unit type values in the range of 0 to 27,
<t>NAL units with NAL unit type values in the range of 0 to 27,
inclusive, may be passed to the decoder. NAL-unit-like structures inclusive, may be passed to the decoder. NAL-unit-like structures
with NAL unit type values in the range of 28 to 31, inclusive, MUST with NAL unit type values in the range of 28 to 31, inclusive, <bcp14>MUST
NOT be passed to the decoder.</t> NOT</bcp14> be passed to the decoder.</t>
<t>The receiver includes a receiver buffer, which is used to compensate
<t>The receiver includes a receiver buffer, which is used to compensate for transmission delay jitter within individual RTP streams and to reorder NAL u
for transmission delay jitter within individual RTP stream, and to reorder NAL u nits from transmission order to the NAL unit decoding order. In this section, t
nits from transmission order to the NAL unit decoding order. In this section, t he
he
receiver operation is described under the assumption that there is no receiver operation is described under the assumption that there is no
transmission delay jitter within an RTP stream. To make a difference from a prac tical receiver buffer that is also used for compensation of transmission delay j itter, the transmission delay jitter within an RTP stream. To make a difference from a prac tical receiver buffer that is also used for compensation of transmission delay j itter, the
receiver buffer is hereafter called the de-packetization buffer in receiver buffer is hereafter called the de-packetization buffer in
this section. Receivers should also prepare for transmission delay this section. Receivers should also prepare for transmission delay
jitter; that is, either reserve separate buffers for transmission jitter, that is, either reserve separate buffers for transmission
delay jitter buffering and de-packetization buffering or use a delay jitter buffering and de-packetization buffering or use a
receiver buffer for both transmission delay jitter and de- receiver buffer for both transmission delay jitter and de-
packetization. Moreover, receivers should take transmission delay packetization. Moreover, receivers should take transmission delay
jitter into account in the buffering operation, e.g., by additional jitter into account in the buffering operation, e.g., by additional
initial buffering before starting of decoding and playback.</t> initial buffering before starting of decoding and playback.</t>
<t>The de-packetization process extracts the NAL units from the RTP packet
<t>The de-packetization process extracts the NAL units from the RTP packets in a s in an RTP stream as follows. When an RTP packet carries a single NAL unit pac
n RTP stream as follows. When an RTP packet carries a single NAL unit packet, t ket, the payload of the RTP packet is extracted as a single NAL unit, excluding
he payload of the RTP packet is extracted as a single NAL unit, excluding the DO the DONL field, i.e., third and fourth bytes, when sprop-max-don-diff is greater
NL field, i.e., third and fourth bytes, when sprop-max-don-diff is greater than than 0. When an RTP packet carries an aggregation packet, several NAL units ar
0. When an RTP packet carries an Aggregation Packet, several NAL units are extr e extracted from the payload of the RTP packet. In this case, each NAL unit cor
acted from the payload of the RTP packet. In this case, each NAL unit correspon responds to the part of the payload of each aggregation unit that follows the NA
ds to the part of the payload of each aggregation unit that follows the NALU siz LU size field, as described in <xref target="aps"/>. When an RTP packet carries
e field as described in Section 4.3.2. When an RTP packet carries a Fragmentati a Fragmentation Unit (FU), all RTP packets from the first FU (with the S field
on Unit (FU), all RTP packets from the first FU (with the S field equal to 1) of equal to 1) of the fragmented NAL unit up to the last FU (with the E field equal
the fragmented NAL unit up to the last FU (with the E field equal to 1) of the to 1) of the fragmented NAL unit are collected. The NAL unit is extracted from
fragmented NAL unit are collected. The NAL unit is extracted from these RTP pac these RTP packets by concatenating all FU payloads in the same order as the cor
kets by concatenating all FU payloads in the same order as the corresponding RTP responding RTP packets and appending the NAL unit header with the fields F, Laye
packets and appending the NAL unit header with the fields F, LayerId, and TID, rId, and TID set to equal the values of the fields F, LayerId, and TID in the pa
set to equal to the values of the fields F, LayerId, and TID in the payload head yload header of the FUs, respectively, and with the NAL unit type set equal to t
er of the FUs respectively, and with the NAL unit type set equal to the value of he value of the field FuType in the FU header of the FUs, as described in <xref
the field FuType in the FU header of the FUs, as described in Section 4.3.3.</t target="funits"/>.</t>
> <t>When sprop-max-don-diff is equal to 0, the de-packetization buffer size
is zero bytes, and the NAL units carried in the single RTP stream are directly
<t>When sprop-max-don-diff is equal to 0, the de-packetization buffer size is ze passed to the decoder in their transmission order, which is identical to their d
ro bytes, and the NAL units carried in the single RTP stream are directly passed ecoding order.</t>
to the decoder in their transmission order, which is identical to their decodin
g order.</t>
<!-- > Informative note: The mapping between RTP and NTP timestamps is
conveyed in RTCP SR packets. In addition, the mechanisms for
faster media timestamp synchronization discussed in {{RFC6051}} may
be used to speed up the acquisition of the RTP-to-wall-clock
mapping. -->
<t>When sprop-max-don-diff is greater than 0, the process described in the remai nder of this section <t>When sprop-max-don-diff is greater than 0, the process described in the remai nder of this section
applies.</t> applies.</t>
<t>There are two buffering states in the receiver: initial buffering and
<t>There are two buffering states in the receiver: initial buffering and
buffering while playing. Initial buffering starts when the reception buffering while playing. Initial buffering starts when the reception
is initialized. After initial buffering, decoding and playback are is initialized. After initial buffering, decoding and playback are
started, and the buffering-while-playing mode is used.</t> started, and the buffering-while-playing mode is used.</t>
<t>Regardless of the buffering state, the receiver stores incoming NAL uni
<t>Regardless of the buffering state, the receiver stores incoming NAL units in ts in reception order into the de-packetization buffer. NAL units carried in RT
reception order into the de-packetization buffer. NAL units carried in RTP pack P packets are stored in the de-packetization
ets are stored in the de-packetization
buffer individually, and the value of AbsDon is calculated and stored for each N AL unit.</t> buffer individually, and the value of AbsDon is calculated and stored for each N AL unit.</t>
<t>Initial buffering lasts until the difference between the greatest and s
<t>Initial buffering lasts until the difference between the greatest and smalles mallest AbsDon values of the NAL units in the de-packetization buffer is greater
t AbsDon values of the NAL units in the de-packetization buffer is greater than than or equal to the value of sprop-max-don-diff.</t>
or equal to the value of sprop-max-don-diff.</t> <t>After initial buffering, whenever the difference between the greatest a
nd smallest AbsDon values of the NAL units in the de-packetization buffer is gre
<t>After initial buffering, whenever the difference between the greatest and sma ater than or equal to the value of sprop-max-don-diff, the following operation i
llest AbsDon values of the NAL units in the de-packetization buffer is greater t s repeatedly applied until this difference is smaller than sprop-max-don-diff:</
han or equal to the value of sprop-max-don-diff, the following operation is repe t>
atedly applied until this difference is smaller than sprop-max-don-diff:</t> <t indent="3">The NAL unit in the de-packetization buffer with the smalles
t
<t><list style="symbols">
<t>The NAL unit in the de-packetization buffer with the smallest
value of AbsDon is removed from the de-packetization buffer and value of AbsDon is removed from the de-packetization buffer and
passed to the decoder.</t> passed to the decoder.</t>
</list></t> <t>When no more NAL units are flowing into the de-packetization buffer,
<t>When no more NAL units are flowing into the de-packetization buffer,
all NAL units remaining in the de-packetization buffer are removed all NAL units remaining in the de-packetization buffer are removed
from the buffer and passed to the decoder in the order of increasing from the buffer and passed to the decoder in the order of increasing
AbsDon values.</t> AbsDon values.</t>
</section>
<section anchor="PayloadFormatParameters">
<name>Payload Format Parameters</name>
<t>This section specifies the optional parameters.
A mapping of the parameters with Session Description Protocol (SDP) <xref
target="RFC8866"/> is also provided for applications that use SDP.</t>
<t>Parameters starting with the string "sprop" for stream properties can b
e used by a sender to provide a receiver with the properties of the stream that
is or will be sent. The media sender (and not the receiver) selects whether, and
with what values, "sprop" parameters are being sent. This uncommon characterist
ic of the "sprop" parameters may not be intuitive in the context of some signali
ng protocol concepts, especially with offer/answer. Please see <xref target="sd
poa"/> for guidance specific to the use of sprop parameters in the offer/answer
case.</t>
<section anchor="oparams">
<name>Media Type Registration</name>
<t>The receiver <bcp14>MUST</bcp14> ignore any parameter unspecified in
this memo.</t>
<dl newline="false" spacing="normal">
<dt>Type name:</dt>
<dd>video</dd>
<dt>Subtype name:</dt>
<dd>H266</dd>
<dt>Required parameters:</dt>
<dd>N/A</dd>
<dt>Optional parameters:</dt>
<dd>profile-id, tier-flag, sub-profile-id, interop-constraints, level-
id, sprop-sublayer-id, sprop-ols-id, recv-sublayer-id, recv-ols-id, max-recv-lev
el-id, sprop-dci, sprop-vps, sprop-sps, sprop-pps, sprop-sei, max-lsr, max-fps,
sprop-max-don-diff, sprop-depack-buf-bytes, depack-buf-cap (refer to <xref targe
t="optionalParameters"/> for definitions).</dd>
<dt>Encoding considerations:</dt>
<dd>This type is only defined for transfer via RTP <xref target="RFC35
50"/>.</dd>
<dt>Security considerations:</dt>
<dd>See <xref target="Security"/> of RFC 9328.</dd>
<dt>Interoperability considerations:</dt>
<dd>N/A</dd>
<dt>Published specification:</dt>
<dd>Please refer to RFC 9328 and VVC coding specification <xref target
="VVC"/>.</dd>
<dt>Applications that use this media type:</dt>
<dd>Any application that relies on VVC-based video services over RTP</
dd>
<dt>Fragment identifier considerations:</dt>
<dd>N/A</dd>
<dt>Additional information:</dt>
<dd>N/A</dd>
<dt>Person &amp; email address to contact for further information:</dt
>
<dd><br/>Stephan Wenger (stewe@stewe.org)</dd>
<dt>Intended usage:</dt>
<dd>COMMON</dd>
<dt>Restrictions on usage:</dt>
<dd>N/A</dd>
<dt>Author:</dt>
<dd>See Authors' Addresses section of RFC 9328.</dd>
<dt>Change controller:</dt>
<dd>IETF &lt;avtcore@ietf.org&gt;</dd>
</dl>
</section>
<section anchor="optionalParameters">
<name>Optional Parameters Definition</name>
<dl newline="true" spacing="normal">
<dt>profile-id, tier-flag, sub-profile-id, interop-constraints, and le
vel-id:</dt>
<dd><t>These parameters indicate the profile, the tier, the default le
vel, the sub-profile, and some constraints of the bitstream carried by the RTP s
tream, or a specific set of the profile, the tier, the default level, the sub-pr
ofile, and some constraints the receiver supports.</t>
<t>The subset of coding tools that may have been used to generate th
e bitstream or that the receiver supports, as well as some additional constraint
s, are indicated collectively by profile-id, sub-profile-id, and interop-constra
ints.</t>
<aside><t>Informative note: There are 128 values of profile-id. The
subset of coding tools identified by profile-id can be further constrained with
up to 255 instances of sub-profile-id. In addition, 68 bits included in intero
p-constraints, which can be extended up to 324 bits, provide means to further re
strict tools from existing profiles. To be able to support this fine-granular s
ignaling of coding-tool subsets with profile-id, sub-profile-id, and interop-con
straints, it would be safe to require symmetric use of these parameters in SDP o
ffer/answer unless recv-ols-id is included in the SDP answer for choosing one of
the layers offered.</t></aside>
<t>The tier is indicated by tier-flag. The default level is indicat
ed by level-id. The tier and the default level specify the limits on values of
syntax elements or arithmetic combinations of values of syntax elements that are
followed when generating the bitstream or that the receiver supports.</t>
<t>In SDP offer/answer, when the SDP answer does not include the rec
v-ols-id parameter that is less than the sprop-ols-id parameter in the SDP offer
, the following applies:</t>
<ul spacing="normal">
<li>The tier-flag, profile-id, sub-profile-id, and interop-constra
ints parameters <bcp14>MUST</bcp14> be used symmetrically, i.e., the value of ea
ch of these parameters in the offer <bcp14>MUST</bcp14> be the same as that in t
he answer, either explicitly signaled or implicitly inferred.</li>
</section> <li>The level-id parameter is changeable as long as the highest le
<section anchor="PayloadFormatParameters"><name>Payload Format Parameters</name> vel indicated by the answer is either equal to or lower than that in the offer.
Note that the highest level higher than level-id in the offer for receiving can
<t>This section specifies the optional parameters. A mapping of the parameters w be included as max-recv-level-id.</li>
ith Session Description Protocol (SDP) <xref target="RFC4556"/> is also provide </ul>
d for applications that use SDP.</t> <t>In SDP offer/answer, when the SDP answer does include the recv-ol
s-id parameter that is less than the sprop-ols-id parameter in the SDP offer, th
<t>Parameters starting with the string "sprop" for stream properties can be used e set of tier-flag, profile-id, sub-profile-id, interop-constraints, and level-i
by a sender to provide a receiver with the properties of the stream that is or d parameters included in the answer <bcp14>MUST</bcp14> be consistent with that
will be sent. The media sender (and not the receiver) selects whether, and with for the chosen output layer set as indicated in the SDP offer, with the exceptio
what values, "sprop" parameters are being sent. This uncommon characteristic of n that the level-id parameter in the SDP answer is changeable as long as the hig
the "sprop" parameters may not be intuitive in the context of some signaling pro hest level indicated by the answer is either lower than or equal to that in the
tocol concepts, especially with offer/answer. Please see <xref target="sdpoa"/> offer.</t>
for guidance specific to the use of sprop parameters in the Offer/Answer case.< <t>More specifications of these parameters, including how they relat
/t> e to syntax elements specified in <xref target="VVC"/>, are provided below.</t>
</dd>
<section anchor="oparams"><name>Media Type Registration</name> <dt>profile-id:</dt>
<dd>
<t>The receiver MUST ignore any parameter unspecified in this memo.</t> <t>When profile-id is not present, a value of 1 (i.e., the Main 10 p
rofile) <bcp14>MUST</bcp14> be inferred.</t>
<t>Type name:            video</t> <t>When used to indicate properties of a bitstream, profile-id is de
rived from the general_profile_idc syntax element that applies to the bitstream
<t>Subtype name:         H266</t> in an instance of the profile_tier_level( ) syntax structure.</t>
<t>VVC bitstreams transported over RTP using the technologies of thi
<t>Required parameters:  N/A</t> s memo <bcp14>SHOULD</bcp14> contain only a single profile_tier_level( ) structu
re in the DCI, unless the sender can assure that a receiver can correctly decode
<t>Optional parameters:</t> the VVC bitstream, regardless of which profile_tier_level( ) structure containe
d in the DCI was used for deriving profile-id and other parameters for the SDP o
<ul empty="true"><li> ffer/answer exchange.</t>
<t>profile-id, tier-flag, sub-profile-id, interop-constraints, level-id, sprop <t>As specified in <xref target="VVC"/>, a profile_tier_level( ) syn
-sublayer-id, sprop-ols-id, recv-sublayer-id, recv-ols-id, max-recv-level-id, sp tax structure may be contained in an SPS NAL unit, and one or more profile_tier_
rop-dci, sprop-vps, sprop-sps, sprop-pps, sprop-sei, max-lsr, max-fps, sprop-max level( ) syntax structures may be contained in a VPS NAL unit and in a DCI NAL u
-don-diff, sprop-depack-buf-bytes, depack-buf-cap (Refer to <xref target="option nit. One of the following three cases applies to the container NAL unit of the
alParameters"/> for definitions).</t> profile_tier_level( ) syntax structure containing syntax elements used to derive
</li></ul> the values of profile-id, tier-flag, level-id, sub-profile-id, or interop-const
raints:</t>
<t>Encoding considerations:</t> <ol type="1">
<li>The container NAL unit is an SPS, the bitstream is a single-lay
<ul empty="true"><li> er bitstream, and the profile_tier_level( ) syntax structures in all SPSs refere
<t>This type is only defined for transfer via RTP (RFC 3550).</t> nced by the CVSs in the bitstream have the same values respectively for those pr
</li></ul> ofile_tier_level( ) syntax elements.</li>
<li>The container NAL unit is a VPS, the profile_tier_level( ) synt
<t>Security considerations:</t> ax structure is the one in the VPS that applies to the OLS corresponding to the
bitstream, and the profile_tier_level( ) syntax structures applicable to the OLS
<ul empty="true"><li> corresponding to the bitstream in all VPSs referenced by the CVSs in the bitstr
<t>See <xref target="Security"/> of RFC XXXX.</t> eam have the same values respectively for those profile_tier_level( ) syntax ele
</li></ul> ments.</li>
<li>The container NAL unit is a DCI NAL unit, and the profile_tier_
<t>Interoperability considerations: N/A</t> level( ) syntax structures in all DCI NAL units in the bitstream have the same v
alues respectively for those profile_tier_level( ) syntax elements.</li>
<t>Published specification:</t> </ol>
<t><xref target="VVC"/> allows for multiple profile_tier_level( ) st
<ul empty="true"><li> ructures in a DCI NAL unit, which may contain different values for the syntax el
<t>Please refer to RFC XXXX and VVC coding specification <xref target="VVC"/>. ements used to derive the values of profile-id, tier-flag, level-id, sub-profile
</t> -id, or interop-constraints in the different entries. However, herein defined i
</li></ul> s only a single profile-id, tier-flag, level-id, sub-profile-id, or interop-cons
traints. When signaling these parameters and a DCI NAL unit is present with mul
<t>Applications that use this media type:</t> tiple profile_tier_level( ) structures, these values <bcp14>SHOULD</bcp14> be th
e same as the first profile_tier_level structure in the DCI, unless the sender h
<ul empty="true"><li> as ensured that
<t>Any application that relies on VVC-based video services over RTP</t>
</li></ul>
<t>Fragment identifier considerations: N/A</t>
<t>Additional information: N/A</t>
<t>Person &amp; email address to contact for further information:</t>
<ul empty="true"><li>
<t>Stephan Wenger (stewe@stewe.org)</t>
</li></ul>
<t>Intended usage: COMMON</t>
<t>Restrictions on usage: N/A</t>
<t>Author: See Authors' Addresses section of RFC XXXX.</t>
<t>Change controller:</t>
<ul empty="true"><li>
<t>IETF &lt;avtcore@ietf.org&gt;</t>
</li></ul>
</section>
<section anchor="optionalParameters"><name>Optional Parameters Definition</name>
<t>profile-id, tier-flag, sub-profile-id, interop-constraints, and level-id:</t>
<ul empty="true"><li>
<t>These parameters indicate the profile, tier, default level, sub-profile, an
d some constraints of the bitstream carried by the RTP stream, or a specific set
of the profile, tier, default level, sub-profile and some constraints the recei
ver supports.</t>
</li></ul>
<ul empty="true"><li>
<t>The subset of coding tools that may have been used to generate the bitstrea
m or that the receiver supports, as well as some additional constraints are indi
cated collectively by profile-id, sub-profile-id, and interop-constraints.</t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: There are 128 values of profile-id. The subset of codi
ng tools identified by the profile-id can be further constrained with up to 255
instances of sub-profile-id. In addition, 68 bits included in interop-constrain
ts, which can be extended up to 324 bits provide means to further restrict tools
from existing profiles. To be able to support this fine-granular signaling of
coding tool subsets with profile-id, sub-profile-id and interop-constraints, it
would be safe to require symmetric use of these parameters in SDP offer/answer u
nless recv-ols-id is included in the SDP answer for choosing one of the layers o
ffered.</t>
</li></ul>
</li></ul>
<ul empty="true"><li>
<t>The tier is indicated by tier-flag. The default level is indicated by leve
l-id. The tier and the default level specify the limits on values of syntax ele
ments or arithmetic combinations of values of syntax elements that are followed
when generating the bitstream or that the receiver supports.</t>
</li></ul>
<ul empty="true"><li>
<t>In SDP offer/answer, when the SDP answer does not include the recv-ols-id p
arameter that is less than the sprop-ols-id parameter in the SDP offer, the foll
owing applies:</t>
</li></ul>
<ul empty="true"><li>
<t><list style="symbols">
<t>The tier-flag, profile-id, sub-profile-id, and interop-constraints parame
ters MUST be used symmetrically, i.e., the value of each of these parameters in
the offer MUST be the same as that in the answer, either explicitly signaled or
implicitly inferred.</t>
</list></t>
</li></ul>
<ul empty="true"><li>
<t><list style="symbols">
<t>The level-id parameter is changeable as long as the highest level indicat
ed by the answer is either equal to or lower than that in the offer. Note that
a highest level higher than level-id in the offer for receiving can be included
as max-recv-level-id.</t>
</list></t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>In SDP offer/answer, when the SDP answer does include the recv-ols-id par
ameter that is less than the sprop-ols-id parameter in the SDP offer, the set of
tier-flag, profile-id, sub-profile-id, interop-constraints, and level-id parame
ters included in the answer MUST be consistent with that for the chosen output l
ayer set as indicated in the SDP offer, with the exception that the level-id par
ameter in the SDP answer is changeable as long as the highest level indicated by
the answer is either lower than or equal to that in the offer.</t>
</li></ul>
</li></ul>
<ul empty="true"><li>
<t>More specifications of these parameters, including how they relate to synta
x elements specified in <xref target="VVC"/> are provided below.</t>
</li></ul>
<t>profile-id:</t>
<ul empty="true"><li>
<t>When profile-id is not present, a value of 1 (i.e., the Main 10 profile) MU
ST be inferred.</t>
</li></ul>
<ul empty="true"><li>
<t>When used to indicate properties of a bitstream, profile-id is derived from
the general_profile_idc syntax element that applies to the bitstream in an inst
ance of the profile_tier_level( ) syntax structure.</t>
</li></ul>
<ul empty="true"><li>
<t>VVC bitstreams transported over RTP using the technologies of this memo SHO
ULD contain only a single profile_tier_level( ) structure in the DCI, unless the
sender can assure that a receiver can correctly decode the VVC bitstream regard
less of which profile_tier_level( ) structure contained in the DCI was used for
deriving profile-id and other parameters for the SDP O/A exchange.</t>
</li></ul>
<ul empty="true"><li>
<t>As specified in <xref target="VVC"/>, a profile_tier_level( ) syntax struct
ure may be contained in an SPS NAL unit, and one or more profile_tier_level( ) s
yntax structures may be contained in a VPS NAL unit and in a DCI NAL unit. One
of the following three cases applies to the container NAL unit of the profile_ti
er_level( ) syntax structure containing syntax elements used to derive the value
s of profile-id, tier-flag, level-id, sub-profile-id, or interop-constraints: 1)
The container NAL unit is an SPS, the bitstream is a single-layer bitstream, an
d the profile_tier_level( ) syntax structures in all SPSs referenced by the CVSs
in the bitstream has the same values respectively for those profile_tier_level(
) syntax elements; 2) The container NAL unit is a VPS, the profile_tier_level(
) syntax structure is the one in the VPS that applies to the OLS corresponding t
o the bitstream, and the profile_tier_level( ) syntax structures applicable to t
he OLS corresponding to the bitstream in all VPSs referenced by the CVSs in the
bitstream have the same values respectively for those profile_tier_level( ) synt
ax elements; 3) The container NAL unit is a DCI NAL unit and the profile_tier_le
vel( ) syntax structures in all DCI NAL units in the bitstream has the same valu
es respectively for those profile_tier_level( ) syntax elements.</t>
</li></ul>
<ul empty="true"><li>
<t><xref target="VVC"/> allows for multiple profile_tier_level( ) structures i
n a DCI NAL unit, which may contain different values for the syntax elements use
d to derive the values of profile-id, tier-flag, level-id, sub-profile-id, or in
terop-constraints in the different entries. However, herein defined is only a s
ingle profile-id, tier-flag, level-id, sub-profile-id, or interop-constraints.
When signaling these parameters and a DCI NAL unit is present with multiple prof
ile_tier_level( ) structures, these values SHOULD be the same as the first profi
le_tier_level structure in the DCI, unless the sender has ensured that
the receiver can decode the bitstream when a different value is chosen.</t> the receiver can decode the bitstream when a different value is chosen.</t>
</li></ul> </dd>
<dt>tier-flag, level-id:</dt>
<t>tier-flag, level-id:</t> <dd>
<t>The value of tier-flag <bcp14>MUST</bcp14> be in the range of 0 t
<ul empty="true"><li> o 1, inclusive. The value of level-id <bcp14>MUST</bcp14> be in the range of 0
<t>The value of tier-flag MUST be in the range of 0 to 1, inclusive. The valu to 255, inclusive.</t>
e of level-id MUST be in the range of 0 to 255, inclusive.</t> <t>If the tier-flag and level-id parameters are used to indicate pro
</li></ul> perties of a bitstream, they indicate the tier and the highest level the bitstre
am complies with.</t>
<ul empty="true"><li> <t>If the tier-flag and level-id parameters are used for capability
<t>If the tier-flag and level-id parameters are used to indicate properties of exchange, the following applies. If max-recv-level-id is not present, the defau
a bitstream, they indicate the tier and the highest level the bitstream complie lt level defined by level-id indicates the highest level the codec wishes to sup
s with.</t> port. Otherwise, max-recv-level-id indicates the highest level the codec support
</li></ul> s for receiving. For either receiving or sending, all levels that are lower tha
n the highest level supported <bcp14>MUST</bcp14> also be supported.</t>
<ul empty="true"><li> <t>If no tier-flag is present, a value of 0 <bcp14>MUST</bcp14> be i
<t>If the tier-flag and level-id parameters are used for capability exchange, nferred; if no level-id is present, a value of 51 (i.e., level 3.1) <bcp14>MUST<
the following applies. If max-recv-level-id is not present, the default level d /bcp14> be inferred.</t>
efined by level-id indicates the highest level the codec wishes to support. Othe <aside><t>Informative note: The level values currently defined in t
rwise, max-recv-level-id indicates the highest level the codec supports for rece he VVC specification are in the form of "majorNum.minorNum", and the value of th
iving. For either receiving or sending, all levels that are lower than the high e level-id for each of the levels is equal to majorNum * 16 + minorNum * 3. It
est level supported MUST also be supported.</t> is expected that, if any levels are defined in the future, the same convention w
</li></ul> ill be used, but this cannot be guaranteed.</t></aside>
<t>When used to indicate properties of a bitstream, the tier-flag an
<ul empty="true"><li> d level-id parameters are derived respectively from the syntax element general_t
<t>If no tier-flag is present, a value of 0 MUST be inferred; if no level-id i ier_flag, and the syntax element general_level_idc or sub_layer_level_idc[j], th
s present, a value of 51 (i.e., level 3.1) MUST be inferred.</t> at apply to the bitstream in an instance of the profile_tier_level( ) syntax str
</li></ul> ucture.</t>
<t>If the tier-flag and level-id are derived from the profile_tier_l
<ul empty="true"><li> evel( ) syntax structure in a DCI NAL unit, the following applies:</t>
<ul empty="true"><li> <ul spacing="normal">
<t>Informative note: The level values currently defined in the VVC specific <li>tier-flag = general_tier_flag</li>
ation are in the form of "majorNum.minorNum", and the value of the level-id for <li>level-id = general_level_idc</li>
each of the levels is equal to majorNum * 16 + minorNum * 3. It is expected tha </ul>
t if any levels are defined in the future, the same convention will be used, but <t>Otherwise, if the tier-flag and level-id are derived from the pro
this cannot be guaranteed.</t> file_tier_level( ) syntax structure in an SPS or VPS NAL unit, and the bitstream
</li></ul> contains the highest sublayer representation in the OLS corresponding to the bi
</li></ul> tstream, the following applies:</t>
<ul spacing="normal">
<ul empty="true"><li> <li>tier-flag = general_tier_flag</li>
<t>When used to indicate properties of a bitstream, the tier-flag and level-id <li>level-id = general_level_idc</li>
parameters are derived respectively from the syntax element general_tier_flag, </ul>
and the syntax element general_level_idc or sub_layer_level_idc[j], that apply t <t>Otherwise, if the tier-flag and level-id are derived from the pro
o the bitstream, in an instance of the profile_tier_level( ) syntax structure.</ file_tier_level( ) syntax structure in an SPS or VPS NAL unit, and the bitstream
t> does not contain the highest sublayer representation in the OLS corresponding t
</li></ul> o the bitstream, the following applies, with j being the value of the sprop-subl
ayer-id parameter:</t>
<ul empty="true"><li> <ul spacing="normal">
<t>If the tier-flag and level-id are derived from the profile_tier_level( ) sy <li>tier-flag = general_tier_flag</li>
ntax structure in a DCI NAL unit, the following applies:</t> <li>level-id = sub_layer_level_idc[j]</li>
</li></ul> </ul>
</dd>
<ul empty="true"><li> <dt>sub-profile-id:</dt>
<t><list style="symbols"> <dd><t>The value of the parameter is a comma-separated (',') list of dat
<t>tier-flag = general_tier_flag</t> a using base64 encoding (<xref target="RFC4648" section="4" sectionFormat="of" /
<t>level-id = general_level_idc</t> >) representation without "==" padding.</t>
</list></t> <t>When used to indicate properties of a bitstream, sub-profile-id is de
</li></ul> rived from each of the ptl_num_sub_profiles general_sub_profile_idc[i] syntax el
ements that apply to the bitstream in a profile_tier_level( ) syntax structure.<
<ul empty="true"><li> /t></dd>
<t>Otherwise, if the tier-flag and level-id are derived from the profile_tier_ <dt>interop-constraints:</dt>
level( ) syntax structure in an SPS or VPS NAL unit, and the bitstream contains <dd><t>A base64 encoding (<xref target="RFC4648" section="4" sectionForm
the highest sublayer representation in the OLS corresponding to the bitstream, t at="of" />)
he following applies:</t> representation of the
</li></ul> data that includes the ptl_frame_only_constraint_flag syntax element,
the ptl_multilayer_enabled_flag syntax element, and the
<ul empty="true"><li> general_constraints_info( ) syntax structure that apply to the
<t><list style="symbols"> bitstream in an instance of the profile_tier_level( ) syntax
<t>tier-flag = general_tier_flag</t> structure.</t>
<t>level-id = general_level_idc</t> <t>If the interop-constraints parameter is not present, the followin
</list></t> g <bcp14>MUST</bcp14> be inferred:</t>
</li></ul> <ul spacing="normal">
<li>ptl_frame_only_constraint_flag = 1</li>
<ul empty="true"><li> <li>ptl_multilayer_enabled_flag = 0</li>
<ul empty="true"><li> <li>gci_present_flag in the general_constraints_info( ) syntax str
<t>Otherwise, if the tier-flag and level-id are derived from the profile_tie ucture = 0</li>
r_level( ) syntax structure in an SPS or VPS NAL unit, and the bitstream does no </ul>
t contain the highest sublayer representation in the OLS corresponding to the bi <t>Using interop-constraints for capability exchange results in a re
tstream, the following applies, with j being the value of the sprop-sublayer-id quirement on any bitstream to be compliant with the interop-constraints.</t>
parameter:</t> </dd>
</li></ul> <dt>sprop-sublayer-id:</dt>
</li></ul> <dd>
<t>This parameter <bcp14>MAY</bcp14> be used to indicate the highest
<ul empty="true"><li> allowed value of TID in the bitstream. When not present, the value of sprop-su
<t><list style="symbols"> blayer-id is inferred to be equal to 6.</t>
<t>tier-flag = general_tier_flag</t> <t>The value of sprop-sublayer-id <bcp14>MUST</bcp14> be in the rang
<t>level-id = sub_layer_level_idc[j]</t> e of 0 to 6, inclusive.</t>
</list></t> </dd>
</li></ul> <dt>sprop-ols-id:</dt>
<dd>
<t>sub-profile-id:</t> <t>This parameter <bcp14>MAY</bcp14> be used to indicate the OLS tha
t the bitstream applies to. When not present, the value of sprop-ols-id is infe
<ul empty="true"><li> rred to be equal to TargetOlsIdx, as specified in Section 8.1.1 of <xref target=
<t>The value of the parameter is a comma-separated (',') list of data using ba "VVC"/>. If this optional parameter is present, sprop-vps <bcp14>MUST</bcp14> al
se64 encoding (Section 4 of <xref target="RFC4648"/>) representation without "== so be present or its content <bcp14>MUST</bcp14> be known a priori at the receiv
" padding.</t> er.</t>
</li></ul> <t>The value of sprop-ols-id <bcp14>MUST</bcp14> be in the range of
0 to 256, inclusive.</t>
<ul empty="true"><li> <aside><t>Informative note: VVC allows having up to 257 output layer
<t>When used to indicate properties of a bitstream, sub-profile-id is derived sets indicated in the VPS, as the number of output layer sets minus 2 is indica
from each of the ptl_num_sub_profiles general_sub_profile_idc[i] syntax elements ted with a field of 8 bits.</t></aside>
that apply to the bitstream in a profile_tier_level( ) syntax structure.</t> </dd>
</li></ul> <dt>recv-sublayer-id:</dt>
<dd><t>This parameter <bcp14>MAY</bcp14> be used to signal a recei
<t>interop-constraints:</t> ver's choice of the offered or declared sublayer representations in sprop-vps an
d sprop-sps. The value of recv-sublayer-id indicates the TID of the highest subl
<ul empty="true"><li> ayer that a receiver supports. When not present, the value of recv-sublayer-id
<t>A base64 encoding (Section 4 of <xref target="RFC4648"/>) representation of is inferred to be equal to the value of the sprop-sublayer-id parameter in the S
the data that includes the syntax elements ptl_frame_only_constraint_flag and p DP offer.</t>
tl_multilayer_enabled_flag and the general_constraints_info( ) syntax structure <t>The value of recv-sublayer-id <bcp14>MUST</bcp14> be in the ran
that apply to the bitstream in an instance of the profile_tier_level( ) syntax s ge of 0 to 6, inclusive.</t></dd>
tructure.</t> <dt>recv-ols-id:</dt>
</li></ul> <dd>
<t>This parameter <bcp14>MAY</bcp14> be used to signal a receiver's
<ul empty="true"><li> choice of the offered or declared output layer sets in sprop-vps. The value of
<t>If the interop-constraints parameter is not present, the following MUST be recv-ols-id indicates the OLS index of the bitstream that a receiver supports.
inferred:</t> When not present, the value of recv-ols-id is inferred to be equal to the value
</li></ul> of the sprop-ols-id parameter inferred from or indicated in the SDP offer. When
present, the value of recv-ols-id must be included only when sprop-ols-id was r
<ul empty="true"><li> eceived and must refer to an output layer set in the VPS that includes no layers
<t><list style="symbols"> other than all or a subset of the layers of the OLS referred to by sprop-ols-id
<t>ptl_frame_only_constraint_flag = 1</t> . If this optional parameter is present, sprop-vps must have been received or i
<t>ptl_multilayer_enabled_flag = 0</t> ts content must be known a priori at the receiver.</t>
<t>gci_present_flag in the general_constraints_info( ) syntax structure = 0< <t>The value of recv-ols-id <bcp14>MUST</bcp14> be in the range of 0
/t> to 256, inclusive.</t>
</list></t> </dd>
</li></ul> <dt>max-recv-level-id:</dt>
<dd>
<ul empty="true"><li> <t>This parameter <bcp14>MAY</bcp14> be used to indicate the highest
<t>Using interop-constraints for capability exchange results in a requirement level a receiver supports.</t>
on any bitstream to be compliant with the interop-constraints.</t> <t>The value of max-recv-level-id <bcp14>MUST</bcp14> be in the rang
</li></ul> e of 0 to 255, inclusive.</t>
<t>When max-recv-level-id is not present, the value is inferred to b
<t>sprop-sublayer-id:</t> e equal to level-id.</t>
<t>max-recv-level-id <bcp14>MUST NOT</bcp14> be present when the hig
<ul empty="true"><li> hest level the receiver supports is not higher than the default level.</t>
<t>This parameter MAY be used to indicate the highest allowed value of TID in </dd>
the bitstream. When not present, the value of sprop-sublayer-id is inferred to <dt>sprop-dci:</dt>
be equal to 6.</t> <dd>This parameter <bcp14>MAY</bcp14> be used to convey a decoding cap
</li></ul> ability information NAL unit of the bitstream for out-of-band transmission. The
parameter <bcp14>MAY</bcp14> also be used for capability exchange.
<ul empty="true"><li> The value of the parameter is a base64 encoding (<xref target="RFC4648"
<t>The value of sprop-sublayer-id MUST be in the range of 0 to 6, inclusive.</ section="4" sectionFormat="of" />) representation of the decoding capability in
t> formation NAL unit, as specified in Section 7.3.2.1 of <xref target="VVC"/>.</dd
</li></ul> >
<dt>sprop-vps:</dt>
<t>sprop-ols-id:</t> <dd>
<t>This parameter <bcp14>MAY</bcp14> be used to convey any video par
<ul empty="true"><li> ameter set to the NAL unit of the bitstream for out-of-band transmission of vide
<t>This parameter MAY be used to indicate the OLS that the bitstream applies t o parameter sets. The parameter <bcp14>MAY</bcp14> also be used for capability
o. When not present, the value of sprop-ols-id is inferred to be equal to Targe exchange and to indicate substream characteristics (i.e., properties of output l
tOlsIdx as specified in 8.1.1 in <xref target="VVC"/>. If this optional paramete ayer sets and sublayer representations, as defined in <xref target="VVC"/>). The
r is present, sprop-vps MUST also be present or its content MUST be known a prio value of the parameter is a comma-separated (',') list of base64 encoding (<xre
ri at the receiver.</t> f target="RFC4648" section="4" sectionFormat="of" />) representations of the vid
</li></ul> eo parameter set NAL units, as specified in Section 7.3.2.3 of <xref target="VVC
"/>.</t>
<ul empty="true"><li> <t>The sprop-vps parameter <bcp14>MAY</bcp14> contain one or more th
<t>The value of sprop-ols-id MUST be in the range of 0 to 256, inclusive.</t> an one video parameter set NAL units. However, all other video parameter sets co
</li></ul> ntained in the sprop-vps parameter <bcp14>MUST</bcp14> be consistent with the fi
rst video parameter set in the sprop-vps parameter. A video parameter set vpsB i
<ul empty="true"><li> s said to be consistent with another video parameter set vpsA if the number of O
<ul empty="true"><li> LSs in vpsA and vpsB are the same and any decoder that conforms to the profile,
<t>Informative note: VVC allows having up to 257 output layer sets indicated tier, level, and constraints indicated by the data starting from the syntax elem
in the VPS as the number of output layer sets minus 2 is indicated with a field ent general_profile_idc to the syntax structure general_constraints_info(), incl
of 8 bits.</t> usive, in the profile_tier_level( ) syntax structure corresponding to any OLS w
</li></ul> ith index olsIdx in vpsA can decode any CVS(s) referencing vpsB when TargetOlsId
</li></ul> x is equal to olsIdx that conforms to the profile, tier, level, and constraints
indicated by the data starting from the syntax element general_profile_idc to th
<t>recv-sublayer-id:</t> e syntax structure general_constraints_info(), inclusive, in the profile_tier_l
evel( ) syntax structure corresponding to the OLS with index TargetOlsIdx in vps
<ul empty="true"><li> B.</t>
<t>This parameter MAY be used to signal a receiver's choice of the offered or </dd>
declared sublayer representations in the sprop-vps and sprop-sps. The value of r <dt>sprop-sps:</dt>
ecv-sublayer-id indicates the TID of the highest sublayer that a receiver suppor <dd>
ts. When not present, the value of recv-sublayer-id is inferred to be equal to <t>This parameter <bcp14>MAY</bcp14> be used to convey sequence para
the value of the sprop-sublayer-id parameter in the SDP offer.</t> meter set NAL units of the bitstream for out-of-band transmission of sequence pa
</li></ul> rameter sets. The value of the parameter is a comma-separated (',') list of bas
e64 encoding (<xref target="RFC4648" section="4" sectionFormat="of" />) represen
<ul empty="true"><li> tations of the sequence parameter set NAL units, as specified in Section 7.3.2.4
<t>The value of recv-sublayer-id MUST be in the range of 0 to 6, inclusive.</t of <xref target="VVC"/>.</t>
> <t>A sequence parameter set spsB is said to be consistent with anot
</li></ul> her sequence parameter set spsA if any decoder that conforms to the profile, tie
r, level, and constraints indicated by the data starting from the syntax element
<t>recv-ols-id:</t> general_profile_idc to the syntax structure general_constraints_info(), inclusi
ve, in the profile_tier_level( ) syntax structure in spsA can decode any CLVS(s
<ul empty="true"><li> ) referencing spsB that conforms to the profile, tier, level, and constraints in
<t>This parameter MAY be used to signal a receiver's choice of the offered or dicated by the data starting from the syntax element general_profile_idc to the
declared output layer sets in the sprop-vps. The value of recv-ols-id indicates syntax structure general_constraints_info(), inclusive, in the profile_tier_leve
the OLS index of the bitstream that a receiver supports. When not present, the l( ) syntax structure in spsB.</t>
value of recv-ols-id is inferred to be equal to value of the sprop-ols-id param </dd>
eter inferred from or indicated in the SDP offer. When present, the value of re <dt>sprop-pps:</dt>
cv-ols-id must be included only when sprop-ols-id was received and must refer to <dd>
an output layer set in the VPS that includes no layers other than all or a subs <t>This parameter <bcp14>MAY</bcp14> be used to convey picture param
et of the layers of the OLS referred to by sprop-ols-id. If this optional param eter set NAL units of the bitstream for out-of-band transmission of picture para
eter is present, sprop-vps must have been received or its content must be known meter sets. The value of the parameter is a comma-separated (',') list of base6
a priori at the receiver.</t> 4 encoding (<xref target="RFC4648" section="4" sectionFormat="of" />) representa
</li></ul> tions of the picture parameter set NAL units, as specified in Section 7.3.2.5 of
<xref target="VVC"/>.</t>
<ul empty="true"><li> </dd>
<t>The value of recv-ols-id MUST be in the range of 0 to 256, inclusive.</t> <dt>sprop-sei:</dt>
</li></ul> <dd>
<t>This parameter <bcp14>MAY</bcp14> be used to convey one or more S
<t>max-recv-level-id:</t> EI messages that describe bitstream characteristics. When present, a decoder ca
n rely on the bitstream characteristics that are described in the SEI messages f
<ul empty="true"><li> or the entire duration of the session, independently from the persistence scopes
<t>This parameter MAY be used to indicate the highest level a receiver support of the SEI messages, as specified in <xref target="VSEI"/>.</t>
s.</t> <t>The value of the parameter is a comma-separated (',') list of bas
</li></ul> e64 encoding (<xref target="RFC4648" section="4" sectionFormat="of" />) represen
tations of SEI NAL units, as specified in <xref target="VSEI"/>.</t>
<ul empty="true"><li> <aside><t>Informative note: Intentionally, no list of applicable or
<t>The value of max-recv-level-id MUST be in the range of 0 to 255, inclusive. inapplicable SEI messages is specified here. Conveying certain SEI messages in
</t> sprop-sei may be sensible in some application scenarios and meaningless in other
</li></ul> s. However, a few examples are described below:</t>
<t>In an environment where the bitstream was created from film-based
<ul empty="true"><li> source material, and no splicing is going to occur during the lifetime of the s
<t>When max-recv-level-id is not present, the value is inferred to be equal to ession, the film grain characteristics SEI message is likely meaningful, and sen
level-id.</t> ding it in sprop-sei, rather than in the bitstream at each entry point, may help
</li></ul> with saving bits and allows one to configure the renderer only once, avoiding u
nwanted artifacts.</t>
<ul empty="true"><li> <t>Examples for SEI messages that would be meaningless to be conveyed
<t>max-recv-level-id MUST NOT be present when the highest level the receiver s in sprop-sei include the decoded picture hash SEI message (it is close to impos
upports is not higher than the default level.</t> sible that all decoded pictures have the same hashtag) or the filler payload SEI
</li></ul> message (as there is no point in just having more bits in SDP).</t>
</aside>
<t>sprop-dci:</t> </dd>
<dt>max-lsr:</dt>
<ul empty="true"><li> <dd>
<t>This parameter MAY be used to convey a decoding capability information NAL <t>The max-lsr <bcp14>MAY</bcp14> be used to signal the capabilities
unit of the bitstream for out-of-band transmission. The parameter MAY also be u of a receiver implementation and <bcp14>MUST NOT</bcp14> be used for any other
sed for capability exchange. The value of the parameter a base64 encoding (Sect purpose. The value of max-lsr is an integer indicating the maximum processing ra
ion 4 of <xref target="RFC4648"/>) representations of the decoding capability in te in units of luma samples per second. The max-lsr parameter signals that the
formation NAL unit as specified in Section 7.3.2.1 of <xref target="VVC"/>.</t> receiver is capable of decoding video at a higher rate than is required by the h
</li></ul> ighest level.</t>
<aside><t>Informative note: When the <bcp14>OPTIONAL</bcp14> media t
<t>sprop-vps:</t> ype parameters are
used to signal the properties of a bitstream, and max-lsr is
<ul empty="true"><li> not present, the values of tier-flag, profile-id, sub-profile-id,
<t>This parameter MAY be used to convey any video parameter set NAL unit of th interop-constraints, and level-id must always be such that
e bitstream for out-of-band transmission of video parameter sets. The parameter the bitstream complies fully with the specified profile,
MAY also be used for capability exchange and to indicate sub-stream characteris sub-profile, tier, level, and interop-constraints.</t></aside>
tics (i.e., properties of output layer sets and sublayer representations as defi <t>When max-lsr is signaled, the receiver <bcp14>MUST</bcp14> be abl
ned in <xref target="VVC"/>). The value of the parameter is a comma-separated (' e to decode bitstreams that conform to the highest level, with the exception tha
,') list of base64 encoding (Section 4 of <xref target="RFC4648"/>) representati t the MaxLumaSr value in Table A.3 of <xref target="VVC"/> for the highest level
ons of the video parameter set NAL units as specified in Section 7.3.2.3 of <xre is replaced with the value of max-lsr. Senders <bcp14>MAY</bcp14> use this kno
f target="VVC"/>.</t> wledge to send pictures of a given size at a higher picture rate than is indicat
</li></ul> ed in the highest level.</t>
<t>When not present, the value of max-lsr is inferred to be equal to
<ul empty="true"><li> the value of MaxLumaSr given in Table A.3 of <xref target="VVC"/> for the highe
<t>The sprop-vps parameter MAY contain one or more than one video parameter se st level.</t>
t NAL units. However, all other video parameter sets contained in the sprop-vps <t>The value of max-lsr <bcp14>MUST</bcp14> be in the range of MaxLu
parameter MUST be consistent with the first video parameter set in the sprop-vps maSr to 16 * MaxLumaSr, inclusive, where MaxLumaSr is given in Table A.3 of <xre
parameter. A video parameter set vpsB is said to be consistent with another vi f target="VVC"/> for the highest level.</t>
deo parameter set vpsA if the number of OLSs in vpsA and vpsB is the same and an </dd>
y decoder that conforms to the profile, tier, level, and constraints indicated b <dt>max-fps:</dt>
y the data starting from the syntax element general_profile_idc to the syntax st <dd>
ructure general_constraints_info(), inclusive, in the profile_tier_level( ) syn <t>The value of max-fps is an integer indicating the maximum picture
tax structure corresponding to any OLS with index olsIdx in vpsA can decode any rate in units of pictures per 100 seconds that can be effectively processed by
CVS(s) referencing vpsB when TargetOlsIdx is equal to olsIdx that conforms to th the receiver. The max-fps parameter <bcp14>MAY</bcp14> be used to signal that t
e profile, tier, level, and constraints indicated by the data starting from the he receiver has a constraint in that it is not capable of processing video effec
syntax element general_profile_idc to the syntax structure general_constraints_i tively at the full picture rate that is implied by the highest level and, when p
nfo(), inclusive, in the profile_tier_level( ) syntax structure corresponding t resent, max-lsr.</t>
o the OLS with index TargetOlsIdx in vpsB.</t> <t>The value of max-fps is not necessarily the picture rate at which
</li></ul> the maximum picture size can be sent; it constitutes a constraint on maximum pi
cture rate for all resolutions.</t>
<t>sprop-sps:</t> <aside><t>Informative note: The max-fps parameter is semantically di
fferent from max-lsr in that max-fps is used to signal a constraint, lowering th
<ul empty="true"><li> e maximum picture rate from what is implied by other parameters.</t></aside>
<t>This parameter MAY be used to convey sequence parameter set NAL units of th <t>The encoder <bcp14>MUST</bcp14> use a picture rate equal to or le
e bitstream for out-of-band transmission of sequence parameter sets. The value ss than this value. In cases where the max-fps parameter is absent, the encoder
of the parameter is a comma-separated (',') list of base64 encoding (Section 4 o is free to choose any picture rate according to the highest level and any signa
f <xref target="RFC4648"/>) representations of the sequence parameter set NAL un led optional parameters.</t>
its as specified in Section 7.3.2.4 of <xref target="VVC"/>.</t> <t>The value of max-fps <bcp14>MUST</bcp14> be smaller than or equal
</li></ul> to the full picture rate that is implied by the highest level and, when present
, max-lsr.</t>
<ul empty="true"><li> </dd>
<t>A sequence parameter set spsB is said to be consistent with another sequen <dt>sprop-max-don-diff:</dt>
ce parameter set spsA if any decoder that conforms to the profile, tier, level, <dd>
and constraints indicated by the data starting from the syntax element general_p <t>If there is no NAL unit naluA that is followed in transmission or
rofile_idc to the syntax structure general_constraints_info(), inclusive, in the der by any NAL unit preceding naluA in decoding order (i.e., the transmission or
profile_tier_level( ) syntax structure in spsA can decode any CLVS(s) referenc der of the NAL units is the same as the decoding order), the value of this param
ing spsB that conforms to the profile, tier, level, and constraints indicated by eter <bcp14>MUST</bcp14> be equal to 0.</t>
the data starting from the syntax element general_profile_idc to the syntax str <t>Otherwise, this parameter specifies the maximum absolute differen
ucture general_constraints_info(), inclusive, in the profile_tier_level( ) synta ce between the decoding order number (i.e., AbsDon) values of any two NAL units
x structure in spsB.</t> naluA and naluB, where naluA follows naluB in decoding order and precedes naluB
</li></ul> in transmission order.</t>
<t>The value of sprop-max-don-diff <bcp14>MUST</bcp14> be an integer
<t>sprop-pps:</t> in the range of 0 to 32767, inclusive.</t>
<t>When not present, the value of sprop-max-don-diff is inferred to
<ul empty="true"><li> be equal to 0.</t>
<t>This parameter MAY be used to convey picture parameter set NAL units of the </dd>
bitstream for out-of-band transmission of picture parameter sets. The value of <dt>sprop-depack-buf-bytes:</dt>
the parameter is a comma-separated (',') list of base64 encoding (Section 4 of <dd>
<xref target="RFC4648"/>) representations of the picture parameter set NAL units <t>This parameter signals the required size of the de-packetization
as specified in Section 7.3.2.5 of <xref target="VVC"/>.</t> buffer in units of bytes. The value of the parameter <bcp14>MUST</bcp14> be gre
</li></ul> ater than or equal to the maximum buffer occupancy (in units of bytes) of the de
-packetization buffer, as specified in <xref target="DepacketizationProcess"/>.<
<t>sprop-sei:</t> /t>
<t>The value of sprop-depack-buf-bytes <bcp14>MUST</bcp14> be an int
<ul empty="true"><li> eger in the range of 0 to 4294967295, inclusive.</t>
<t>This parameter MAY be used to convey one or more SEI messages that describe <t>When sprop-max-don-diff is present and greater than 0, this param
bitstream characteristics. When present, a decoder can rely on the bitstream c eter <bcp14>MUST</bcp14> be present and the value <bcp14>MUST</bcp14> be greater
haracteristics that are described in the SEI messages for the entire duration of than 0. When not present, the value of sprop-depack-buf-bytes is inferred to b
the session, independently from the persistence scopes of the SEI messages as s e equal to 0.</t>
pecified in <xref target="VSEI"/>.</t> <aside><t>Informative note: The value of sprop-depack-buf-bytes indi
</li></ul> cates the required size of the de-packetization buffer only. When network jitte
r can occur, an appropriately sized jitter buffer has to be available as well.</
<ul empty="true"><li> t></aside>
<t>The value of the parameter is a comma-separated (',') list of base64 encodi </dd>
ng (Section 4 of <xref target="RFC4648"/>) representations of SEI NAL units as s <dt>depack-buf-cap:</dt>
pecified in <xref target="VSEI"/>.</t> <dd>
</li></ul> <t>This parameter signals the capabilities of a receiver implementat
ion and indicates the amount of de-packetization buffer space in units of bytes
<ul empty="true"><li> that the receiver has available for reconstructing the NAL unit decoding order f
<ul empty="true"><li> rom NAL units carried in the RTP stream. A receiver is able to handle any RTP s
<t>Informative note: Intentionally, no list of applicable or inapplicable SE tream for which the value of the sprop-depack-buf-bytes parameter is smaller tha
I messages is specified here. Conveying certain SEI messages in sprop-sei may b n or equal to this parameter.</t>
e sensible in some application scenarios and meaningless in others. However, a <t>When not present, the value of depack-buf-cap is inferred to be e
few examples are described below:</t> qual to 4294967295. The value of depack-buf-cap <bcp14>MUST</bcp14> be an integ
</li></ul> er in the range of 1 to 4294967295, inclusive.</t>
</li></ul> <aside><t>Informative note: depack-buf-cap indicates the maximum pos
sible size of the de-packetization buffer of the receiver only, without allowing
<ul empty="true"><li> for network jitter.</t></aside>
<ul empty="true"><li> </dd>
<t>1) In an environment where the bitstream was created from film-based sour </dl>
ce material, and no splicing is going to occur during the lifetime of the sessio </section>
n, the film grain characteristics SEI message is likely meaningful, and sending <section anchor="sdp-parameters">
it in sprop-sei rather than in the bitstream at each entry point may help with s <name>SDP Parameters</name>
aving bits and allows one to configure the renderer only once, avoiding unwanted <t>The receiver <bcp14>MUST</bcp14> ignore any parameter unspecified in
artifacts.</t> this memo.</t>
</li></ul> <section anchor="mapping-of-payload-type-parameters-to-sdp">
</li></ul> <name>Mapping of Payload Type Parameters to SDP</name>
<t>The media type video/H266 string is mapped to fields in the Session
<ul empty="true"><li>
<ul empty="true"><li>
<t>2) Examples for SEI messages that would be meaningless to be conveyed in
sprop-sei include the decoded picture hash SEI message (it is close to impossibl
e that all decoded pictures have the same hashtag) or the filler payload SEI mes
sage (as there is no point in just having more bits in SDP).</t>
</li></ul>
</li></ul>
<t>max-lsr:</t>
<ul empty="true"><li>
<t>The max-lsr MAY be used to signal the capabilities of a receiver implementa
tion and MUST NOT be used for any other purpose. The value of max-lsr is an inte
ger indicating the maximum processing rate in units of luma samples per second.
The max-lsr parameter signals that the receiver is capable of decoding video at
a higher rate than is required by the highest level.</t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: When the OPTIONAL media type parameters are used to sig
nal the properties of a bitstream, and max-lsr is not present, the values of tie
r-flag, profile-id, sub-profile-id interop-constraints, and level-id must always
be such that the bitstream complies fully with the specified profile, tier, and
level.</t>
</li></ul>
</li></ul>
<ul empty="true"><li>
<t>When max-lsr is signaled, the receiver MUST be able to decode bitstreams th
at conform to the highest level, with the exception that the MaxLumaSr value in
Table 136 of <xref target="VVC"/> for the highest level is replaced with the val
ue of max-lsr. Senders MAY use this knowledge to send pictures of a given size
at a higher picture rate than is indicated in the highest level.</t>
</li></ul>
<ul empty="true"><li>
<t>When not present, the value of max-lsr is inferred to be equal to the value
of MaxLumaSr given in Table 136 of <xref target="VVC"/> for the highest level.<
/t>
</li></ul>
<ul empty="true"><li>
<t>The value of max-lsr MUST be in the range of MaxLumaSr to 16 * MaxLumaSr, i
nclusive, where MaxLumaSr is given in Table 136 of <xref target="VVC"/> for the
highest level.</t>
</li></ul>
<t>max-fps:</t>
<ul empty="true"><li>
<t>The value of max-fps is an integer indicating the maximum picture rate in u
nits of pictures per 100 seconds that can be effectively processed by the receiv
er. The max-fps parameter MAY be used to signal that the receiver has a constra
int in that it is not capable of processing video effectively at the full pictur
e rate that is implied by the highest level and, when present, max-lsr.</t>
</li></ul>
<ul empty="true"><li>
<t>The value of max-fps is not necessarily the picture rate at which the maxim
um picture size can be sent, it constitutes a constraint on maximum picture rate
for all resolutions.</t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: The max-fps parameter is semantically different from ma
x-lsr in that max-fps is used to signal a constraint, lowering the maximum pictu
re rate from what is implied by other parameters.</t>
</li></ul>
</li></ul>
<ul empty="true"><li>
<t>The encoder MUST use a picture rate equal to or less than this value. In c
ases where the max-fps parameter is absent, the encoder is free to choose any pi
cture rate according to the highest level and any signaled optional parameters.<
/t>
</li></ul>
<ul empty="true"><li>
<t>The value of max-fps MUST be smaller than or equal to the full picture rate
that is implied by the highest level and, when present, max-lsr.</t>
</li></ul>
<t>sprop-max-don-diff:</t>
<ul empty="true"><li>
<t>If there is no NAL unit naluA that is followed in transmission order by any
NAL unit preceding naluA in decoding order (i.e., the transmission order of the
NAL units is the same as the decoding order), the value of this parameter MUST
be equal to 0.</t>
</li></ul>
<ul empty="true"><li>
<t>Otherwise, this parameter specifies the maximum absolute difference between
the decoding order number (i.e., AbsDon) values of any two NAL units naluA and
naluB, where naluA follows naluB in decoding order and precedes naluB in transmi
ssion order.</t>
</li></ul>
<ul empty="true"><li>
<t>The value of sprop-max-don-diff MUST be an integer in the range of 0 to 327
67, inclusive.</t>
</li></ul>
<ul empty="true"><li>
<t>When not present, the value of sprop-max-don-diff is inferred to be equal t
o 0.</t>
</li></ul>
<t>sprop-depack-buf-bytes:</t>
<ul empty="true"><li>
<t>This parameter signals the required size of the de-packetization buffer in
units of bytes. The value of the parameter MUST be greater than or equal to the
maximum buffer occupancy (in units of bytes) of the de-packetization buffer as
specified in Section 6.</t>
</li></ul>
<ul empty="true"><li>
<t>The value of sprop-depack-buf-bytes MUST be an integer in the range of 0 to
4294967295, inclusive.</t>
</li></ul>
<ul empty="true"><li>
<t>When sprop-max-don-diff is present and greater than 0, this parameter MUST
be present and the value MUST be greater than 0. When not present, the value of
sprop-depack-buf-bytes is inferred to be equal to 0.</t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: The value of sprop-depack-buf-bytes indicates the requi
red size of the de-packetization buffer only. When network jitter can occur, an
appropriately sized jitter buffer has to be available as well.</t>
</li></ul>
</li></ul>
<t>depack-buf-cap:</t>
<ul empty="true"><li>
<t>This parameter signals the capabilities of a receiver implementation and in
dicates the amount of de-packetization buffer space in units of bytes that the r
eceiver has available for reconstructing the NAL unit decoding order from NAL un
its carried in the RTP stream. A receiver is able to handle any RTP stream for
which the value of the sprop-depack-buf-bytes parameter is smaller than or equal
to this parameter.</t>
</li></ul>
<ul empty="true"><li>
<t>When not present, the value of depack-buf-cap is inferred to be equal to 42
94967295. The value of depack-buf-cap MUST be an integer in the range of 1 to 4
294967295, inclusive.</t>
</li></ul>
<ul empty="true"><li>
<ul empty="true"><li>
<t>Informative note: depack-buf-cap indicates the maximum possible size of t
he de-packetization buffer of the receiver only, without allowing for network ji
tter.</t>
</li></ul>
</li></ul>
</section>
<section anchor="sdp-parameters"><name>SDP Parameters</name>
<t>The receiver MUST ignore any parameter unspecified in this memo.</t>
<section anchor="mapping-of-payload-type-parameters-to-sdp"><name>Mapping of Pay
load Type Parameters to SDP</name>
<t>The media type video/H266 string is mapped to fields in the Session
Description Protocol (SDP) <xref target="RFC8866"/> as follows:</t> Description Protocol (SDP) <xref target="RFC8866"/> as follows:</t>
<ul spacing="normal">
<t><list style="symbols"> <li>The media name in the "m=" line of SDP <bcp14>MUST</bcp14> be vi
<t>The media name in the "m=" line of SDP MUST be video.</t> deo.</li>
<t>The encoding name in the "a=rtpmap" line of SDP MUST be H266 (the media sub <li>The encoding name in the "a=rtpmap" line of SDP <bcp14>MUST</bcp
type).</t> 14> be H266 (the media subtype).</li>
<t>The clock rate in the "a=rtpmap" line MUST be 90000.</t> <li>The clock rate in the "a=rtpmap" line <bcp14>MUST</bcp14> be 900
<t>The OPTIONAL parameters profile-id, tier-flag, sub-profile-id, interop-cons 00.</li>
traints, level-id, sprop-sublayer-id, sprop-ols-id, recv-sublayer-id, recv-ols-i <li>The <bcp14>OPTIONAL</bcp14> parameters profile-id, tier-flag, su
d, max-recv-level-id, max-lsr, max-fps, sprop-max-don-diff, sprop-depack-buf-byt b-profile-id, interop-constraints, level-id, sprop-sublayer-id, sprop-ols-id, re
es and depack-buf-cap, when present, MUST be included in the "a=fmtp" line of SD cv-sublayer-id, recv-ols-id, max-recv-level-id, max-lsr, max-fps, sprop-max-don-
P. The fmtp line is expressed as a media type string, in the form of a semicolo diff, sprop-depack-buf-bytes, and depack-buf-cap, when present, <bcp14>MUST</bcp
n-separated list of parameter=value pairs.</t> 14> be included in the "a=fmtp" line of SDP. The fmtp line is expressed as a me
<t>The OPTIONAL parameter sprop-vps, sprop-sps, sprop-pps, sprop-sei, and spro dia type string, in the form of a semicolon-separated list of parameter=value pa
p-dci, when present, MUST be included in the "a=fmtp" line of SDP or conveyed us irs.</li>
ing the "fmtp" source attribute as specified in Section 6.3 of <xref target="RFC <li><t>The <bcp14>OPTIONAL</bcp14> parameters sprop-vps, sprop-sps,
5576"/>. For a particular media format (i.e., RTP payload type), sprop-vps, spro sprop-pps, sprop-sei, and sprop-dci, when present, <bcp14>MUST</bcp14> be includ
p-sps, sprop-pps, sprop-sei, or sprop-dci MUST NOT be both included in the "a=fm ed in the "a=fmtp" line of SDP or conveyed using the "fmtp" source attribute as
tp" line of SDP and conveyed using the "fmtp" source attribute. When included i specified in <xref target="RFC5576" section="6.3" sectionFormat="of" />. For a p
n the "a=fmtp" line of SDP, those parameters are expressed as a media type strin articular media format (i.e., RTP payload type), sprop-vps, sprop-sps, sprop-pps
g, in the form of a semicolon-separated list of parameter=value pairs. When con , sprop-sei, or sprop-dci <bcp14>MUST NOT</bcp14> be both included in the "a=fmt
veyed in the "a=fmtp" line of SDP for a particular payload type, the parameters p" line of SDP and conveyed using the "fmtp" source attribute. When included in
sprop-vps, sprop-sps, sprop-pps, sprop-sei, and sprop-dci MUST be applied to eac the "a=fmtp" line of SDP, those parameters are expressed as a media type string
h SSRC with the payload type. When conveyed using the "fmtp" source attribute, , in the form of a semicolon-separated list of parameter=value pairs. When conv
these parameters are only associated with the given source and payload type as p eyed in the "a=fmtp" line of SDP for a particular payload type, the parameters s
arts of the "fmtp" source attribute.</t> prop-vps, sprop-sps, sprop-pps, sprop-sei, and sprop-dci <bcp14>MUST</bcp14> be
</list></t> applied to each SSRC with the payload type. When conveyed using the "fmtp" sour
ce attribute, these parameters are only associated with the given source and pay
<ul empty="true"><li> load type as parts of the "fmtp" source attribute.</t>
<ul empty="true"><li> </li>
<t>Informative note: Conveyance of sprop-vps, sprop-sps, and sprop-pps using </ul>
the "fmtp" source attribute allows for out-of-band transport of parameter sets <aside><t>Informative note: Conveyance of sprop-vps, sprop-sps, an
in topologies like Topo-Video-switch-MCU as specified in <xref target="RFC7667"/ d sprop-pps using the "fmtp" source attribute allows for out-of-band transport o
></t> f parameter sets in topologies like Topo-Video-switch-MCU, as specified in <xref
</li></ul> target="RFC7667"/>.</t></aside>
</li></ul> <t>A general usage of media representation in SDP is as follows:</t>
<artwork name="" type="" align="left" alt=""><![CDATA[
<t>An general usage of media representation in SDP is as follows:</t>
<figure><artwork><![CDATA[
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 H266/90000 a=rtpmap:98 H266/90000
a=fmtp:98 profile-id=1; a=fmtp:98 profile-id=1;
sprop-vps=<video parameter sets data>; sprop-vps=<video parameter sets data>;
sprop-sps=<sequence parameter set data>; sprop-sps=<sequence parameter set data>;
sprop-pps=<picture parameter set data>; sprop-pps=<picture parameter set data>;
]]></artwork></figure> ]]></artwork>
<t>A SIP offer/answer exchange wherein both parties are expected to bo
<t>A SIP Offer/Answer exchange wherein both parties are expected to both send an th send and receive could look like the following. Only the media codec-specifi
d receive could look like the following. Only the media codec-specific parts of c parts of the SDP are shown. Some lines are wrapped due to text constraints.</
the SDP are shown. Some lines are wrapped due to text constraints.</t> t>
<artwork name="" type="" align="left" alt=""><![CDATA[
<figure><artwork><![CDATA[
Offerer->Answerer: Offerer->Answerer:
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 H266/90000 a=rtpmap:98 H266/90000
a=fmtp:98 profile-id=1; level_id=83; a=fmtp:98 profile-id=1; level_id=83;
]]></artwork></figure> ]]></artwork>
<t>The above represents an offer for symmetric video communication usi
<t>The above represents an offer for symmetric video communication using <xref t ng <xref target="VVC"/> and its payload specification at the main profile and le
arget="VVC"/> and it's payload specification, at the main profile and level 5.1 vel 5.1 (and as the levels are downgradable, all lower levels). Informally spea
(and, as the levels are downgradable, all lower levels. Informally speaking, th king, this offer tells the receiver of the offer that the sender is willing to r
is offer tells the receiver of the offer that the sender is willing to receive u eceive up to 4Kp60 resolution at the maximum bitrates specified in <xref target=
p to 4Kp60 resolution at the maximum bitrates specified in <xref target="VVC"/>. "VVC"/>. At the same time, if this offer were accepted "as is", the offer can e
At the same time, if this offer were accepted “as is”, the offer can expect th xpect that the answerer would be able to receive and properly decode H.266 media
at the answerer would be able to receive and properly decode H.266 media up to a up to and including level 5.1.</t>
nd including level 5.1.</t> <artwork name="" type="" align="left" alt=""><![CDATA[
<figure><artwork><![CDATA[
Answerer->Offerer: Answerer->Offerer:
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 H266/90000 a=rtpmap:98 H266/90000
a=fmtp:98 profile-id=1; level_id=67 a=fmtp:98 profile-id=1; level_id=67
]]></artwork></figure> ]]></artwork>
<t>With this answer to the offer above, the system receiving the offer
<t>With this answer to the offer above, the system receiving the offer advises t advises the offerer that it is incapable of handing H.266 at level 5.1 but is c
he offerer that it is incapable of handing H.266 at level 5.1 but is capable of apable of decoding 1080p60. As H.266 video codecs must support decoding at all
decoding 1080p60. As H.266 video codecs must support decoding at all levels bel levels below the maximum level they implement, the resulting user experience wou
ow the maximum level they implement, the resulting user experience would likely ld likely be that both systems send video at 1080p60. However, nothing prevents
be that both systems send video at 1080p60. However, nothing prevents an encode an encoder from further downgrading its sending to, for example, 720p30 if it w
r from further downgrading its sending to, for example 720p30 if it were short o ere short of cycles or bandwidth or for other reasons.</t>
f cycles, bandwidth, or for other reasons.</t> </section>
<section anchor="sdpoa">
</section> <name>Usage with SDP Offer/Answer Model</name>
<section anchor="sdpoa"><name>Usage with SDP Offer/Answer Model</name> <t>This section describes the negotiation of unicast messages using th
e offer/answer model as described in <xref target="RFC3264"/> and its updates.
<t>This section describes the negotiation of unicast messages using the offer-an The section is split into subsections, covering a) media format configurations n
swer model as described in <xref target="RFC3264"/> and its updates. The sectio ot involving non-temporal scalability; b) scalable media format configurations;
n is split into subsections, covering a) media format configurations not involvi c) the description of the use of those parameters not involving the media config
ng non-temporal scalability; b) scalable media format configurations; c) the des uration itself but rather the parameters of the payload format design; and d) mu
cription of the use of those parameters not involving the media configuration it lticast.</t>
self but rather the parameters of the payload format design; and d) multicast.</ <section anchor="non-scalable-media-format-configuration">
t> <name>Non-scalable Media Format Configuration</name>
<t>A non-scalable VVC media configuration is such a configuration wh
<section anchor="non-scalable-media-format-configuration"><name>Non-scalable med ere no non-temporal scalability mechanisms are allowed. In <xref target="VVC"/>
ia format configuration</name> version 1, it is implied that general_profile_idc indicates one of the followin
g profiles: Main 10, Main 10 Still Picture, Main 10 4:4:4, or Main 10 4:4:4 Stil
<t>A non-scalable VVC media configuration is such a configuration where no non-t l Picture, with general_profile_idc values of 1, 65, 33, and 97, respectively.
emporal scalability mechanisms are allowed. In <xref target="VVC"/> version 1, Note that non-scalable media configurations include temporal scalability inline
that implies that general_profile_idc indicates one of the following profiles: M with VVC's design philosophy and profile structure.</t>
ain10, Main10 Still Picture, Main 10 4:4:4, Main10 4:4:4 Still Picture, with gen <t>The following limitations and rules pertaining to the media confi
eral_profile_idc values of 1, 65, 33, and 97, respectively. Note that non-scala guration apply:</t>
ble media configurations includes temporal scalability, inline with VVC’s design <ul spacing="normal">
philosophy and profile structure.</t> <li><t>The parameters identifying a media format configuration for
VVC are profile-id, tier-flag, sub-profile-id, level-id, and interop-constraint
<t>The following limitations and rules pertaining to the media configuration app s. These media configuration parameters, except level-id, <bcp14>MUST</bcp14> b
ly:</t> e used symmetrically.</t>
<t>The answerer <bcp14>MUST</bcp14> structure its answer accordi
<t><list style="symbols"> ng to one of the following three options:</t>
<t>The parameters identifying a media format configuration for VVC are profile <ol spacing="normal">
-id, tier-flag, sub-profile-id, level-id, and interop-constraints. These media <li>maintain all configuration parameters with the values remai
configuration parameters, except level-id, MUST be used symmetrically.</t> ning the same as in the offer for the media format (payload type), with the exce
</list></t> ption that the value of level-id is changeable as long as the highest level indi
cated by the answer is not higher than that indicated by the offer;</li>
<ul empty="true"><li> <li>include in the answer the recv-sublayer-id parameter, with
<t>The answerer MUST structure its answer in according to one of the following a value less than the sprop-sublayer-id parameter in the offer, for the media fo
three options:</t> rmat (payload type), and maintain all configuration parameters with the values r
</li></ul> emaining the same as in the offer for the media format (payload type), with the
exception that the value of level-id is changeable as long as the highest level
<ul empty="true"><li> indicated by the answer is not higher than the level indicated by sprop-sps or s
<t>1) maintain all configuration parameters with the values remaining the same prop-vps in offer for the chosen sublayer representation; or</li>
as in the offer for the media format (payload type), with the exception that th <li>remove the media format (payload type) completely (when one
e value of level-id is changeable as long as the highest level indicated by the or more of the parameter values are not supported).</li>
answer is not higher than that indicated by the offer;</t> </ol>
</li></ul> </li>
</ul>
<ul empty="true"><li> <aside><t>Informative note: The above requirement for symmetric use
<t>2) include in the answer the recv-sublayer-id parameter, with a value less does not apply for level-id and does not apply for the other bitstream or RTP st
than the sprop-sublayer-id parameter in the offer, for the media format (payload ream properties and capability parameters, as described in <xref target="payload
type), and maintain all configuration parameters with the values remaining the formatconfig"/> below.</t></aside>
same as in the offer for the media format (payload type), with the exception tha <ul spacing="normal">
t the value of level-id is changeable as long as the highest level indicated by <li>To simplify handling and matching of these configurations, the
the answer is not higher than the level indicated by the sprop-sps or sprop-vps same RTP payload type number used in the offer <bcp14>SHOULD</bcp14> also be us
in offer for the chosen sublayer representation; or</t> ed in the answer, as specified in <xref target="RFC3264"/>.</li>
</li></ul> <li><t>The same RTP payload type number used in the offer for the
media subtype H266 <bcp14>MUST</bcp14> be used in the answer when the answer inc
<ul empty="true"><li> ludes recv-sublayer-id. When the answer does not include recv-sublayer-id, the
<t>3) remove the media format (payload type) completely (when one or more of t answer <bcp14>MUST NOT</bcp14> contain a payload type number used in the offer f
he parameter values are not supported).</t> or the media subtype H266 unless the configuration is exactly the same as in the
</li></ul> offer or the configuration in the answer only differs from that in the offer wi
th a different value of level-id. The answer <bcp14>MAY</bcp14> contain the rec
<ul empty="true"><li> v-sublayer-id parameter if a VVC bitstream contains multiple operation points (u
<ul empty="true"><li> sing temporal scalability and sublayers) and sprop-sps or sprop-vps is included
<ul empty="true"><li> in the offer where information of sublayers are present in the first sequence pa
<t>Informative note: The above requirement for symmetric use does not appl rameter set or video parameter set contained in sprop-sps or sprop-vps, respecti
y for level-id, and does not apply for the other bitstream or RTP stream propert vely. If sprop-sps or sprop-vps is provided in an offer, an answerer <bcp14>MAY
ies and capability parameters as described in <xref target="payloadformatconfig" </bcp14> select a particular operation point indicated in the first sequence par
/> below.</t> ameter set or video parameter set contained in sprop-sps or sprop-vps, respectiv
</li></ul> ely. When the answer includes a recv-sublayer-id that is less than a sprop-subl
</li></ul> ayer-id in the offer, the following applies:</t>
</li></ul> <ol spacing="normal">
<li>When the sprop-sps parameter is present, all sequence paramete
<t><list style="symbols"> r sets contained in the sprop-sps parameter in the
<t>To simplify handling and matching of these configurations, the same RTP pay SDP answer and all sequence parameter sets sent in-band for either the offerer-t
load type number used in the offer SHOULD also be used in the answer, as specifi o-answerer direction or the answerer-to-offerer direction <bcp14>MUST</bcp14> be
ed in <xref target="RFC3264"/>.</t> consistent with the first sequence parameter set in the sprop-sps parameter of
<t>The same RTP payload type number used in the offer for the media subtype H2 the offer (see the semantics of sprop-sps in <xref target="oparams"/> of this do
66 MUST be used in the answer when the answer includes recv-sublayer-id. When t cument on one sequence parameter set being consistent with another sequence para
he answer does not include recv-sublayer-id, the answer MUST NOT contain a paylo meter set).</li>
ad type number used in the offer for the media subtype H266 unless the configura <li>When the sprop-vps parameter is present, all video parameter s
tion is exactly the same as in the offer or the configuration in the answer only ets contained in the sprop-vps parameter in the
differs from that in the offer with a different value of level-id. The answer SDP answer and all video parameter sets sent in-band for either the offerer-to-a
MAY contain the recv-sublayer-id parameter if an VVC bitstream contains multiple nswerer direction or the answerer-to-offerer direction <bcp14>MUST</bcp14> be co
operation points (using temporal scalability and sublayers) and sprop-sps or sp nsistent with the first video parameter set in the sprop-vps parameter of the of
rop-vps is included in the offer where information of sublayers are present in t fer (see the semantics of sprop-vps in <xref target="oparams"/> of this document
he first sequence parameter set or video parameter set contained in sprop-sps or on one video parameter set being consistent with another video parameter set).<
sprop-vps respectively. If the sprop-sps or sprop-vps is provided in an offer, /li>
an answerer MAY select a particular operation point indicated in the first sequ <li>The bitstream sent in either direction <bcp14>MUST</bcp14> con
ence parameter set or video parameter set contained in sprop-sps or sprop-vps re form to the profile, tier, level, and constraints of the chosen sublayer represe
spectively. When the answer includes a recv-sublayer-id that is less than a spr ntation, as indicated by the profile_tier_level( ) syntax structure in the first
op-sublayer-id in the offer, the following applies:</t> sequence parameter set in the sprop-sps parameter or by the first profile_tier_
</list></t> level( ) syntax structure in the first video parameter set in the sprop-vps para
meter of the offer.</li>
<ul empty="true"><li> </ol>
<t>1) When sprop-sps parameter is present, all sequence parameter sets contain </li>
ed in the sprop-sps parameter in the </ul>
SDP answer and all sequence parameter sets sent in-band for either the offerer-t <aside><t>Informative note: When an offerer receives an answer that
o-answerer direction or the answerer-to-offerer direction MUST be consistent wit does not include recv-sublayer-id, it has to compare payload types not declared
h the first sequence parameter set in the sprop-sps parameter of the offer (see in the offer based on the media type (i.e., video/H266) and the above media conf
the semantics of sprop-sps in <xref target="oparams"/> of this document on one s iguration parameters with any payload types it has already declared. This will
equence parameter set being consistent with another sequence parameter set).</t> enable it
</li></ul> to determine whether the configuration in question is new or if it is equivalent
to configuration already offered, since a different payload type number may be
<ul empty="true"><li> used in the answer. The ability to perform operation point selection enables a
<t>2) When sprop-vps parameter is present, all video parameter sets contained receiver to utilize the temporal scalable nature of a VVC bitstream.</t></aside>
in the sprop-vps parameter in the </section>
SDP answer and all video parameter sets sent in-band for either the offerer-to-a <section anchor="scalable-media-format-configuration">
nswerer direction or the answerer-to-offerer direction MUST be consistent with t <name>Scalable Media Format Configuration</name>
he first video parameter set in the sprop-vps parameter of the offer (see the se <t>A scalable VVC media configuration is such a configuration where
mantics of sprop-vps in <xref target="oparams"/> of this document on one video p non-temporal scalability mechanisms are allowed. In <xref target="VVC"/> versio
arameter set being consistent with another video parameter set).</t> n 1, it is implied that general_profile_idc indicates one of the following prof
</li></ul> iles: Multilayer Main 10 and Multilayer Main 10 4:4:4, with general_profile_idc
values of 17 and 49, respectively.</t>
<ul empty="true"><li> <t>The following limitations and rules pertaining to the media confi
<t>3) The bitstream sent in either direction MUST conform to the profile, tier guration apply. They are listed in an order that would be logical for an implem
, level, and constraints of the chosen sublayer representation as indicated by t entation to follow:</t>
he profile_tier_level( ) syntax structure in the first sequence parameter set in <ul spacing="normal">
the sprop-sps parameter or by the first profile_tier_level( ) syntax structure <li>The parameters identifying a media format configuration for sc
in the first video parameter set in the sprop-vps parameter of the offer.</t> alable VVC are profile-id, tier-flag, sub-profile-id, level-id, interop-constrai
</li></ul> nts, and sprop-vps. These media configuration parameters, except level-id, <bcp
14>MUST</bcp14> be used symmetrically, except as noted below.</li>
<ul empty="true"><li> <li>The answerer <bcp14>MAY</bcp14> include a level-id that <bcp14
<ul empty="true"><li> >MUST</bcp14> be lower than or equal to the level-id indicated in the offer (eit
<ul empty="true"><li> her expressed by level-id in the offer or implied by the default level, as speci
<t>Informative note: When an offerer receives an answer that does not incl fied in <xref target="oparams"/>).</li>
ude recv-sublayer-id, it has to compare payload types not declared in the offer <li>When sprop-ols-id is present in an offer, sprop-vps <bcp14>MUS
based on the media type (i.e., video/H266) and the above media configuration par T</bcp14> also be present in the same offer and include at least one valid VPS s
ameters with any payload types it has already declared. This will enable it o to allow the answerer to meaningfully interpret sprop-ols-id and select recv-o
to determine whether the configuration in question is new or if it is equivalent ls-id (see below).</li>
to configuration already offered, since a different payload type number may be <li><t>The answerer <bcp14>MUST NOT</bcp14> include recv-ols-id un
used in the answer. The ability to perform operation point selection enables a less the offer includes sprop-ols-id. When present, recv-ols-id <bcp14>MUST</bcp
receiver to utilize the temporal scalable nature of an VVC bitstream.</t> 14> indicate a supported output layer set in the VPS that includes no layers oth
</li></ul> er than all or a subset of the layers of the OLS referred to by sprop-ols-id. I
</li></ul> f unable, the answerer <bcp14>MUST</bcp14> remove the media format.</t></li>
</li></ul> </ul>
<aside><t>Informative note: If an offerer wants to offer more than
</section> one output layer set, it can do so by offering multiple VVC media with differen
<section anchor="scalable-media-format-configuration"><name>Scalable media forma t payload types.</t></aside>
t configuration</name> <ul spacing="normal">
<li>The offerer <bcp14>MAY</bcp14> include sprop-sublayer-id, whic
<t>A scalable VVC media configuration is such a configuration where non-temporal h indicates the highest allowed value of TID in the bitstream. The answerer <bc
scalability mechanisms are allowed. In <xref target="VVC"/> version 1, that im p14>MAY</bcp14> include recv-sublayer-id, which can be used to reduce the number
plies that general_profile_idc indicates one of the following profiles: Multilay of sublayers from the value of sprop-sublayer-id.</li>
er Main 10, and Multilayer Main 10 4:4:4, with general_profile_idc values of 17 <li>When the answerer includes recv-ols-id and configuration param
and 49, respectively.</t> eters profile-id, tier-flag, sub-profile-id, level-id, and interop-constraints,
it <bcp14>MUST</bcp14> use the configuration parameter values as signaled in the
<t>The following limitations and rules pertaining to the media configuration app sprop-vps for the operating point with the largest number of sublayers for the
ly. They are listed in an order that would be logical for an implementation to chosen output layer set, with the exception that the value of level-id is change
follow:</t> able as long as the highest level indicated by the answer is not higher than the
level indicated by sprop-vps in offer for the operating point with the largest
<t><list style="symbols"> number of sublayers for the chosen output layer set.</li>
<t>The parameters identifying a media format configuration for scalable VVC ar </ul>
e profile-id, tier-flag, sub-profile-id, level-id, interop-constraints, and spro </section>
p-vps. These media configuration parameters, except level-id, MUST be used symm <section anchor="payloadformatconfig">
etrically, except as noted below.</t> <name>Payload Format Configuration</name>
<t>The answerer MAY include a level-id that MUST be lower than or equal to the <t>The following limitations and rules pertain to the configuration
level-id indicated in the offer (either expressed by level-id in the offer, or of the payload format buffer management mostly and apply to both scalable and no
implied by the default level as specific in <xref target="oparams"/>).</t> n-scalable VVC.</t>
<t>When sprop-ols-id is present in an offer, sprop-vps MUST also be present in <ul spacing="normal">
the same offer and including at least one valid VPS, so to allow the answerer t <li><t>The parameters sprop-max-don-diff and sprop-depack-buf-byte
o meaningfully interpret sprop-ols-id and select recv-ols-id (see below).</t> s describe the properties of an RTP stream that the offerer or the answerer is s
<t>The answerer MUST NOT include recv-ols-id unless the offer includes sprop-o ending for the media format configuration. This differs from the normal usage o
ls-id. When present, recv-ols-id MUST indicate a supported output layer set in t f the offer/answer parameters; normally, such parameters declare the properties
he VPS that includes no layers other than all or a subset of the layers of the O of the bitstream or RTP stream that the offerer or the answerer is able to recei
LS referred to by sprop-ols-id. If unable, the answerer MUST remove the media f ve. When dealing with VVC, the offerer assumes that the answerer will be able t
ormat.</t> o receive media encoded using the configuration being offered.</t></li>
</list></t> </ul>
<aside><t>Informative note: The above parameters apply for any RTP
<ul empty="true"><li> stream, when present, sent by a declaring entity with the same configuration. I
<ul empty="true"><li> n other words, the applicability of the above parameters to RTP streams depends
<t>Informative note: if an offerer wants to offer more than one output layer on the source endpoint. Rather than being bound to the payload type, the values
set, it can do so by offering multiple VVC media with different payload types.< may have to be applied to another payload type when being sent, as they apply fo
/t> r the configuration.</t></aside>
</li></ul> <ul spacing="normal">
</li></ul> <li>The capability parameter max-lsr <bcp14>MAY</bcp14> be used to
declare further capabilities of the offerer or answerer for receiving. It <bcp1
<t><list style="symbols"> 4>MUST NOT</bcp14> be present when the direction attribute is sendonly.</li>
<t>The offerer MAY include sprop-sublayer-id which indicates the highest allow <li>The capability parameter max-fps <bcp14>MAY</bcp14> be used to
ed value of TID in the bitstream. The answerer MAY include recv-sublayer-id whi declare lower capabilities of the offerer or answerer for receiving. It <bcp14
ch can be used to reduce the number of sublayers from the value of sprop-sublaye >MUST NOT</bcp14> be present when the direction attribute is sendonly.</li>
r-id.</t> <li>When an offerer offers an interleaved stream, indicated by the
<t>When the answerer includes recv-ols-id and configuration parameters profile presence of sprop-max-don-diff with a value larger than zero, the offerer <bcp1
-id, tier-flag, sub-profile-id, level-id, and interop-constraints, it MUST use t 4>MUST</bcp14> include the size of the de-packetization buffer sprop-depack-buf-
he configuration parameter values as signaled in the sprop-vps for the operating bytes.</li>
point with the largest number of sublayers for the chosen output layer set, wit <li>To enable the offerer and answerer to inform each other about
h the exception that the value of level-id is changeable as long as the highest their capabilities for de-packetization buffering in receiving RTP streams, both
level indicated by the answer is not higher than the level indicated by the spro parties are <bcp14>RECOMMENDED</bcp14> to include depack-buf-cap.</li>
p-vps in offer for the operating point with the largest number of sublayers for <li>The parameters sprop-dci, sprop-vps, sprop-sps, or sprop-pps,
the chosen output layer set.</t> when present (included in the "a=fmtp" line of SDP or conveyed using the "fmtp"
</list></t> source attribute, as specified in <xref target="RFC5576" section="6.3" sectionFo
rmat="of" />), are used for out-of-band transport of the parameter sets (DCI, VP
</section> S, SPS, or PPS, respectively).</li>
<section anchor="payloadformatconfig"><name>Payload format configuration</name> <li>The answerer <bcp14>MAY</bcp14> use either out-of-band or in-b
and transport of parameter sets for the bitstream it is sending, regardless of w
<t>The following limitations and rules pertain to the configuration of the paylo hether out-of-band parameter sets transport has been used in the offerer-to-answ
ad format buffer management mostly and apply to both scalable and non-scalable V erer direction. Parameter sets included in an answer are independent of those p
VC.</t> arameter sets included in the offer, as they are used for decoding two different
bitstreams; one from the answerer to the offerer and the other in the opposite
<t><list style="symbols"> direction. In case some RTP packets are sent before the SDP offer/answer settle
<t>The parameters sprop-max-don-diff, and sprop-depack-buf-bytes describe the s down, in-band parameter sets <bcp14>MUST</bcp14> be used for those RTP stream
properties of an RTP stream that the offerer or the answerer is sending for the parts sent before the SDP offer/answer.</li>
media format configuration. This differs from the normal usage of the offer/ans <li><t>The following rules apply to transport of parameter sets in
wer parameters: normally such parameters declare the properties of the bitstream the offerer-to-answerer direction.</t>
or RTP stream that the offerer or the answerer is able to receive. When dealin <ul spacing="normal">
g with VVC, the offerer assumes that the answerer will be able to receive media <li>An offer <bcp14>MAY</bcp14> include sprop-dci, sprop-vps, sp
encoded using the configuration being offered.</t> rop-sps, and/or sprop-pps. If none of these parameters are present in the offer,
</list></t> then only in-band transport of parameter sets is used.</li>
<li>If the level to use in the offerer-to-answerer direction is
<ul empty="true"><li> equal to the default level in the offer, the answerer <bcp14>MUST</bcp14> be pre
<ul empty="true"><li> pared to use the parameter sets included in sprop-vps, sprop-sps, and sprop-pps
<t>Informative note: The above parameters apply for any RTP stream, when pr (either included in the "a=fmtp" line of SDP or conveyed using the "fmtp" source
esent, sent by a declaring entity with the same configuration. In other words, attribute) for decoding the incoming bitstream, e.g., by passing these paramete
the applicability of the above parameters to RTP streams depends on the source e r set NAL units to the video decoder before passing any NAL units carried in the
ndpoint. Rather than being bound to the payload type, the values may have to be RTP streams. Otherwise, the answerer <bcp14>MUST</bcp14> ignore sprop-vps, spr
applied to another payload type when being sent, as they apply for the configura op-sps, and sprop-pps (either included in the "a=fmtp" line of SDP or conveyed u
tion.</t> sing the "fmtp" source attribute) and the offerer <bcp14>MUST</bcp14> transmit p
</li></ul> arameter sets in-band.</li>
</li></ul> </ul>
</li>
<t><list style="symbols"> <li><t>The following rules apply to transport of parameter sets in
<t>The capability parameter max-lsr MAY be used to declare further capabilitie the answerer-to-offerer direction.</t>
s of the offerer or answerer for receiving. It MUST NOT be present when the dire <ul spacing="normal">
ction attribute is sendonly.</t> <li>An answer <bcp14>MAY</bcp14> include sprop-dci, sprop-vps,
<t>The capability parameter max-fps MAY be used to declare lower capabilities sprop-sps, and/or sprop-pps. If none of these parameters are present in the ans
of the offerer or answerer for receiving. It MUST NOT be present when the direc wer, then only in-band transport of parameter sets is used.</li>
tion attribute is sendonly.</t> <li>The offerer <bcp14>MUST</bcp14> be prepared to use the par
<t>When an offerer offers an interleaved stream, indicated by the presence of ameter sets included in sprop-vps, sprop-sps, and sprop-pps (either included in
sprop-max-don-diff with a value larger than zero, the offerer MUST include the s the "a=fmtp" line of SDP or conveyed using the "fmtp" source attribute) for deco
ize of the de-packetization buffer sprop-depack-buf-bytes.</t> ding the incoming bitstream, e.g., by passing these parameter set NAL units to t
<t>To enable the offerer and answerer to inform each other about their capabil he video decoder before passing any NAL units carried in the RTP streams.</li>
ities for de-packetization buffering in receiving RTP streams, both parties are </ul>
RECOMMENDED to include depack-buf-cap.</t> </li>
<t>The sprop-dci, sprop-vps, sprop-sps, or sprop-pps, when present (included i <li>When sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps are con
n the "a=fmtp" line of SDP or conveyed using the "fmtp" source attribute as spec veyed using the "fmtp" source attribute, as specified in <xref target="RFC5576"
ified in Section 6.3 of <xref target="RFC5576"/>), are used for out-of-band tran section="6.3" sectionFormat="of" />, the receiver of the parameters <bcp14>MUST<
sport of the parameter sets (DCI, VPS, SPS, or PPS, respectively).</t> /bcp14> store the parameter sets
<t>The answerer MAY use either out-of-band or in-band transport of parameter s included in sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps and associate them
ets for the bitstream it is sending, regardless of whether out-of-band parameter with the source given as part of the "fmtp" source attribute. Parameter sets as
sets transport has been used in the offerer-to-answerer direction. Parameter s sociated with one source (given as part of the "fmtp" source attribute) <bcp14>M
ets included in an answer are independent of those parameter sets included in th UST</bcp14> only be used to decode NAL units conveyed in RTP packets from the sa
e offer, as they are used for decoding two different bitstreams, one from the an me source (given as part of the "fmtp" source attribute). When this mechanism i
swerer to the offerer and the other in the opposit direction. In case some RTP s in use, SSRC collision detection and resolution <bcp14>MUST</bcp14> be perform
packets are sent before the SDP offer/answer settles down, in-band parameter set ed as specified in <xref target="RFC5576"/>.</li>
s MUST be used for those RTP stream parts sent before the SDP offer/answer.</t> </ul>
<t>The following rules apply to transport of parameter set in the offerer-to-a <t><xref target="parameters"/> lists the interpretation of all the p
nswerer direction.</t> arameters that <bcp14>MAY</bcp14> be
</list></t>
<ul empty="true"><li>
<t><list style="symbols">
<t>An offer MAY include sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps. I
f none of these parameters is present in the offer, then only in-band transport
of parameter sets is used.</t>
</list></t>
</li></ul>
<ul empty="true"><li>
<t><list style="symbols">
<t>If the level to use in the offerer-to-answerer direction is equal to the
default level in the offer, the answerer MUST be prepared to use the parameter s
ets included in sprop-vps, sprop-sps, and sprop-pps (either included in the "a=f
mtp" line of SDP or conveyed using the "fmtp" source attribute) for decoding the
incoming bitstream, e.g., by passing these parameter set NAL units to the video
decoder before passing any NAL units carried in the RTP streams. Otherwise, th
e answerer MUST ignore sprop-vps, sprop-sps, and sprop-pps (either included in t
he "a=fmtp" line of SDP or conveyed using the "fmtp" source attribute) and the o
fferer MUST transmit parameter sets in-band.</t>
</list></t>
</li></ul>
<t><list style="symbols">
<t>The following rules apply to transport of parameter set in the answerer-to-
offerer direction.</t>
</list></t>
<ul empty="true"><li>
<t><list style="symbols">
<t>An answer MAY include sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps.
If none of these parameters is present in the answer, then only in-band transpor
t of parameter sets is used.</t>
</list></t>
</li></ul>
<ul empty="true"><li>
<t><list style="symbols">
<t>The offerer MUST be prepared to use the parameter sets included in sprop-
vps, sprop-sps, and sprop-pps (either included in the "a=fmtp" line of SDP or co
nveyed using the "fmtp" source attribute) for decoding the incoming bitstream, e
.g., by passing these parameter set NAL units to the video decoder before passin
g any NAL units carried in the RTP streams.</t>
</list></t>
</li></ul>
<t><list style="symbols">
<t>When sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps are conveyed using t
he "fmtp" source attribute as specified in Section 6.3 of <xref target="RFC5576"
/>, the receiver of the parameters MUST store the parameter sets
included in sprop-dci, sprop-vps, sprop-sps, and/or sprop-pps and associate them
with the source given as part of the "fmtp" source attribute. Parameter sets as
sociated with one source (given as part of the "fmtp" source attribute) MUST onl
y be used to decode NAL units conveyed in RTP packets from the same source (give
n as part of the "fmtp" source attribute). When this mechanism is in use, SSRC
collision detection and resolution MUST be performed as specified in <xref targe
t="RFC5576"/>.</t>
</list></t>
<t>Table 1 lists the interpretation of all the parameters that MAY be
used for the various combinations of offer, answer, and direction used for the various combinations of offer, answer, and direction
attributes. Note that the two columns wherein the recv-ols-id attributes.</t>
parameter is used only apply to answers, whereas the other columns <figure anchor="parameters">
apply to both offers and answers.</t> <name>Interpretation of Parameters for Various Combinations
of Offers, Answers, and Direction Attributes, with and without recv-ols-id
<figure><artwork><![CDATA[ .</name>
<artwork name="" type="" align="left" alt=""><![CDATA[
sendonly --+ sendonly --+
answer: recvonly, recv-ols-id --+ | answer: recvonly, recv-ols-id --+ |
recvonly w/o recv-ols-id --+ | | recvonly w/o recv-ols-id --+ | |
answer: sendrecv, recv-ols-id --+ | | | answer: sendrecv, recv-ols-id --+ | | |
sendrecv w/o recv-ols-id --+ | | | | sendrecv w/o recv-ols-id --+ | | | |
| | | | | | | | | |
profile-id C D C D P profile-id C D C D P
tier-flag C D C D P tier-flag C D C D P
level-id D D D D P level-id D D D D P
sub-profile-id C D C D P sub-profile-id C D C D P
skipping to change at line 2055 skipping to change at line 1487
sprop-dci P P - - P sprop-dci P P - - P
sprop-sei P P - - P sprop-sei P P - - P
sprop-vps P P - - P sprop-vps P P - - P
sprop-sps P P - - P sprop-sps P P - - P
sprop-pps P P - - P sprop-pps P P - - P
sprop-sublayer-id P P - - P sprop-sublayer-id P P - - P
recv-sublayer-id O O O O - recv-sublayer-id O O O O -
sprop-ols-id P P - - P sprop-ols-id P P - - P
recv-ols-id X O X O - recv-ols-id X O X O -
Table 1. Interpretation of parameters for various combinations of
offers, answers, direction attributes, with and without recv-ols-id.
Columns that do not indicate offer or answer apply to both.
Legend: Legend:
C: configuration for sending and receiving bitstreams C: configuration for sending and receiving bitstreams
D: changeable configuration, same as C except possible D: changeable configuration, same as C, except possible
to answer with a different but consistent value (see the to answer with a different but consistent value (see the
semantics of the six parameters related to profile, tier, semantics of the six parameters related to profile, tier,
and level on these parameters being consistent) and level on these parameters being consistent)
P: properties of the bitstream to be sent P: properties of the bitstream to be sent
R: receiver capabilities R: receiver capabilities
O: operation point selection O: operation point selection
X: MUST NOT be present X: MUST NOT be present
-: not usable, when present MUST be ignored -: not usable, when present MUST be ignored
]]></artwork></figure> ]]></artwork>
</figure>
<t>Parameters used for declaring receiver capabilities are, in general, <t>Parameters used for declaring receiver capabilities are, in gener
downgradable; i.e., they express the upper limit for a sender's al,
possible behavior. Thus, a sender MAY select to set its encoder downgradable, i.e., they express the upper limit for a sender's
possible behavior. Thus, a sender <bcp14>MAY</bcp14> select to set its encoder
using only lower/lesser or equal values of these parameters.</t> using only lower/lesser or equal values of these parameters.</t>
<t>When the answer does not include a recv-ols-id that is less
<t>When the answer does not include a recv-ols-id that is less
than the sprop-ols-id in the offer, parameters declaring a than the sprop-ols-id in the offer, parameters declaring a
configuration point are not changeable, with the exception of the configuration point are not changeable, with the exception of the
level-id parameter for unicast usage, and these parameters express level-id parameter for unicast usage, and these parameters express
values a receiver expects to be used and MUST be used verbatim in the values a receiver expects to be used and <bcp14>MUST</bcp14> be used verbatim in the
answer as in the offer.</t> answer as in the offer.</t>
<t>When a sender's capabilities are declared with the configuration
<t>When a sender's capabilities are declared with the configuration
parameters, these parameters express a configuration that is parameters, these parameters express a configuration that is
acceptable for the sender to receive bitstreams. In order to achieve acceptable for the sender to receive bitstreams. In order to achieve
high interoperability levels, it is often advisable to offer multiple high interoperability levels, it is often advisable to offer multiple
alternative configurations. It is impossible to offer multiple alternative configurations. It is impossible to offer multiple
configurations in a single payload type. Thus, when multiple configurations in a single payload type. Thus, when multiple
configuration offers are made, each offer requires its own RTP configuration offers are made, each offer requires its own RTP
payload type associated with the offer. However, it is possible to payload type associated with the offer. However, it is possible to
offer multiple operation points using one configuration in a single offer multiple operation points using one configuration in a single
payload type by including sprop-vps in the offer and recv-ols-id in the answer.< /t> payload type by including sprop-vps in the offer and recv-ols-id in the answer.< /t>
<t>An implementation <bcp14>SHOULD</bcp14> be able to understand all
<t>An implementation SHOULD be able to understand all media type parameters media type parameters
(including all optional media type parameters), even if it doesn’t support (including all optional media type parameters), even if it doesn't support
the functionality related to the parameter. This, in conjunction with proper the functionality related to the parameter. This, in conjunction with proper
application logic in the implementation allows the implementation, application logic in the implementation, allows the implementation,
after having received an offer, to create an answer by potentially downgrading after having received an offer, to create an answer by potentially downgrading
one or more of the optional parameters to the point where the implementation one or more of the optional parameters to the point where the implementation
can cope, leading to higher chances of interoperability beyond the most basic can cope, leading to higher chances of interoperability beyond the most basic
interop points (for which, as described above, no optional parameters are necess ary).</t> interop points (for which, as described above, no optional parameters are necess ary).</t>
<aside><t>Informative note: In implementations of previous H.26x
<ul empty="true"><li> payload formats, it was
<t>Informative note: in implementations of previous H.26x payload formats it w
as
occasionally observed that implementations were incapable of parsing most (or al l) occasionally observed that implementations were incapable of parsing most (or al l)
of the optional parameters. As a result, the offer-answer exchange resulted in a of the optional parameters. As a result, the offer/answer exchange resulted in a
baseline performance (using the default values for the optional parameters) with baseline performance (using the default values for the optional parameters) with
the resulting suboptimal user experience. However, there are valid reasons to f orego the resulting suboptimal user experience. However, there are valid reasons to f orego
the implementation complexity of implementing the parsing of some or all of the optional the implementation complexity of implementing the parsing of some or all of the optional
parameters, for example, when there is pre-determined knowledge, not negotiated by an parameters, for example, when there is predetermined knowledge, not negotiated b y an
SDP-based offer/answer process, of the capabilities of the involved systems SDP-based offer/answer process, of the capabilities of the involved systems
(walled gardens, baseline requirements defined in application standards higher u (walled gardens, baseline requirements defined in application standards higher u
p in the stack, and similar).</t> p in the stack, and similar).</t></aside>
</li></ul> <t>An answerer <bcp14>MAY</bcp14> extend the offer with additional m
edia format
<t>An answerer MAY extend the offer with additional media format configurations. However, to enable their usage, in most cases, a
configurations. However, to enable their usage, in most cases a
second offer is required from the offerer to provide the bitstream second offer is required from the offerer to provide the bitstream
property parameters that the media sender will use. This also has property parameters that the media sender will use. This also has
the effect that the offerer has to be able to receive this media the effect that the offerer has to be able to receive this media
format configuration, not only to send it.</t> format configuration, not only to send it.</t>
</section>
</section> </section>
</section> <section anchor="multicast">
<section anchor="multicast"><name>Multicast</name> <name>Multicast</name>
<t>For bitstreams being delivered over multicast, the following rules
<t>For bitstreams being delivered over multicast, the following rules apply:</t> apply:</t>
<ul spacing="normal">
<t><list style="symbols"> <li>The media format configuration is identified by profile-id, tier
<t>The media format configuration is identified by profile-id, tier-flag, sub- -flag, sub-profile-id, level-id, and interop-constraints. These media format co
profile-id, level-id, and interop-constraints. These media format configuration nfiguration parameters, including level-id, <bcp14>MUST</bcp14> be used symmetri
parameters, including level-id, MUST be used symmetrically; that is, the answer cally; that is, the answerer <bcp14>MUST</bcp14> either maintain all configurati
er MUST either maintain all configuration parameters or remove the media format on parameters or remove the media format (payload type) completely. Note that t
(payload type) completely. Note that this implies that the level-id for offer/a his implies that the level-id for offer/answer in multicast is not changeable.</
nswer in multicast is not changeable.</t> li>
<t>To simplify the handling and matching of these configurations, the same RTP <li>To simplify the handling and matching of these configurations, t
payload type number used in the offer SHOULD also be used in the answer, as spe he same RTP payload type number used in the offer <bcp14>SHOULD</bcp14> also be
cified in <xref target="RFC3264"/>. An answer MUST NOT contain a payload type n used in the answer, as specified in <xref target="RFC3264"/>. An answer <bcp14>
umber used in the offer unless the configuration is the same as in the offer.</t MUST NOT</bcp14> contain a payload type number used in the offer unless the conf
> iguration is the same as in the offer.</li>
<t>Parameter sets received MUST be associated with the originating source and <li>Parameter sets received <bcp14>MUST</bcp14> be associated with t
MUST only be used in decoding the incoming bitstream from the same source.</t> he originating source and <bcp14>MUST</bcp14> only be used in decoding the incom
<t>The rules for other parameters are the same as above for unicast as long as ing bitstream from the same source.</li>
the three above rules are obeyed.</t> <li>The rules for other parameters are the same as above for unicast
</list></t> as long as the three above rules are obeyed.</li>
</ul>
</section> </section>
<section anchor="usage-in-declarative-session-descriptions"><name>Usage in Decla <section anchor="usage-in-declarative-session-descriptions">
rative Session Descriptions</name> <name>Usage in Declarative Session Descriptions</name>
<t>When VVC over RTP is offered with SDP in a declarative style, as in
<t>When VVC over RTP is offered with SDP in a declarative style, as in Real Time Real Time Streaming Protocol (RTSP) <xref target="RFC7826"/> or Session Announc
Streaming Protocol (RTSP) <xref target="RFC7826"/> or Session Announcement Prot ement Protocol (SAP) <xref target="RFC2974"/>, the following considerations are
ocol (SAP) <xref target="RFC2974"/>, the following considerations are necessary. necessary.</t>
</t> <ul spacing="normal">
<li><t>All parameters capable of indicating both bitstream propertie
<t><list style="symbols"> s and receiver capabilities are used to indicate only bitstream properties. For
<t>All parameters capable of indicating both bitstream properties and receiver example, in this case, the parameters profile-id,
capabilities are used to indicate only bitstream properties. For example, in t tier-id, and level-id declare the values used by the bitstream, not the capabili
his case, the parameter profile-id, ties for receiving bitstreams. As a result, the following interpretation of the
tier-id, level-id declares the values used by the bitstream, not the capabilitie parameters <bcp14>MUST</bcp14> be used:</t>
s for receiving bitstreams. As a result, the following interpretation of the pa <ul spacing="normal">
rameters MUST be used:</t> <li><t>Declaring actual configuration or bitstream properties:</
</list></t> t>
<ul spacing="normal">
<ul empty="true"><li> <li>profile-id</li>
<t><list style="symbols"> <li>tier-flag</li>
<t>Declaring actual configuration or bitstream properties: <li>level-id</li>
<list style="symbols"> <li>interop-constraints</li>
<t>profile-id</t> <li>sub-profile-id</li>
<t>tier-flag</t> <li>sprop-dci</li>
<t>level-id</t> <li>sprop-vps</li>
<t>interop-constraints</t> <li>sprop-sps</li>
<t>sub-profile-id</t> <li>sprop-pps</li>
<t>sprop-dci</t> <li>sprop-max-don-diff</li>
<t>sprop-vps</t> <li>sprop-depack-buf-bytes</li>
<t>sprop-sps</t> <li>sprop-sublayer-id</li>
<t>sprop-pps</t> <li>sprop-ols-id</li>
<t>sprop-max-don-diff</t> <li>sprop-sei</li>
<t>sprop-depack-buf-bytes</t> </ul>
<t>sprop-sublayer-id</t> </li>
<t>sprop-ols-id</t> <li>
<t>sprop-sei</t> <t>Not usable (when present, they <bcp14>MUST</bcp14> be ignor
</list></t> ed):</t>
</list></t> <ul spacing="normal">
</li></ul> <li>max-lsr</li>
<li>max-fps</li>
<ul empty="true"><li> <li>max-recv-level-id</li>
<t><list style="symbols"> <li>depack-buf-cap</li>
<t>Not usable (when present, they MUST be ignored): <li>recv-sublayer-id</li>
<list style="symbols"> <li>recv-ols-id</li>
<t>max-lsr</t> </ul>
<t>max-fps</t> </li>
<t>max-recv-level-id</t> <li>A receiver of the SDP is required to support all parameters
<t>depack-buf-cap</t> and values of the parameters provided; otherwise, the receiver <bcp14>MUST</bcp1
<t>recv-sublayer-id</t> 4> reject (RTSP) or not participate in (SAP) the session. It falls on the creat
<t>recv-ols-id</t> or of the session to use values that are expected to be supported by the receivi
</list></t> ng application.</li>
</list></t> </ul>
</li></ul> </li>
</ul>
<ul empty="true"><li> </section>
<t><list style="symbols"> <section anchor="considerations-for-parameter-sets">
<t>A receiver of the SDP is required to support all parameters and values of <name>Considerations for Parameter Sets</name>
the parameters provided; otherwise, the receiver MUST reject (RTSP) or not part <t>When out-of-band transport of parameter sets is used, parameter set
icipate in (SAP) the session. It falls on the creator of the session to use val s <bcp14>MAY</bcp14> still be additionally transported in-band unless explicitly
ues that are expected to be supported by the receiving application.</t> disallowed by an application, and some of these additional parameter sets may u
</list></t> pdate some of the out-of-band transported parameter sets. An update of a paramet
</li></ul> er set refers to the sending of a parameter set of the same type using the same
parameter set ID but with different values for at least one other parameter of t
</section> he parameter set.</t>
<section anchor="considerations-for-parameter-sets"><name>Considerations for Par </section>
ameter Sets</name> </section>
</section>
<t>When out-of-band transport of parameter sets is used, parameter sets MAY stil <section anchor="FeedbackMessage">
l be additionally transported in-band unless explicitly disallowed by an applica <name>Use with Feedback Messages</name>
tion, and some of these additional parameter sets may update some of the out-of- <t>The following subsections define the use of the Picture Loss
band transported parameter sets. Update of a parameter set refers to the sending
of a parameter set of the same type using the same parameter set ID but with di
fferent values for at least one other parameter of the parameter set.</t>
</section>
</section>
</section>
<section anchor="FeedbackMessage"><name>Use with Feedback Messages</name>
<t>The following subsections define the use of the Picture Loss
Indication (PLI) and Full Intra Request (FIR) feedback Indication (PLI) and Full Intra Request (FIR) feedback
messages with <xref target="VVC"/>. The PLI is defined in messages with <xref target="VVC"/>. The PLI is defined in
<xref target="RFC4585"/>, and the FIR message is defined in <xref target="RFC510 4"/>. <xref target="RFC4585"/>, and the FIR message is defined in <xref target="RFC510 4"/>.
In accordance with this memo, unlike <xref target="HEVC"/>, a sender MUST NOT se In accordance with this memo, unlike <xref target="HEVC"/>, a sender <bcp14>MUST
nd Slice Loss Indication (SLI) or Reference Picture Selection Indication (RPSI), NOT</bcp14> send Slice Loss Indication (SLI) or Reference Picture Selection Ind
and a receiver SHOULD ignore RPSI and treat a received SLI as a PLI.</t> ication (RPSI), and a receiver <bcp14>SHOULD</bcp14> ignore RPSI and treat a rec
eived SLI as a PLI.</t>
<section anchor="PLI"><name>Picture Loss Indication (PLI)</name> <section anchor="PLI">
<name>Picture Loss Indication (PLI)</name>
<t>As specified in RFC 4585, Section 6.3.1, the reception of a PLI by a <t>As specified in <xref target="RFC4585" section="6.3.1" sectionFormat=
"of" />, the reception of a PLI by a
media sender indicates "the loss of an undefined amount of coded media sender indicates "the loss of an undefined amount of coded
video data belonging to one or more pictures". Without having any video data belonging to one or more pictures". Without having any
specific knowledge of the setup of the bitstream (such as use and specific knowledge of the setup of the bitstream (such as use and
location of in-band parameter sets, non-IRAP decoder refresh points, location of in-band parameter sets, non-IRAP decoder refresh points,
picture structures, and so forth), a reaction to the reception of an picture structures, and so forth), a reaction to the reception of a
PLI by a VVC sender SHOULD be to send an IRAP picture and relevant PLI by a VVC sender <bcp14>SHOULD</bcp14> be to send an IRAP picture and relevan
parameter sets; potentially with sufficient redundancy so to ensure t
parameter sets, potentially with sufficient redundancy so to ensure
correct reception. However, sometimes information about the correct reception. However, sometimes information about the
bitstream structure is known. For example, state could have been bitstream structure is known.
established outside of the mechanisms defined in this document that For example, such information can be parameter sets that have been conveyed out
parameter sets are conveyed out of band only, and stay static for the of band through mechanisms not defined in this document and that are known to st
duration of the session. In that case, it is obviously unnecessary ay static for the duration of the session. In that case, it is obviously unneces
sary
to send them in-band as a result of the reception of a PLI. Other to send them in-band as a result of the reception of a PLI. Other
examples could be devised based on a priori knowledge of different examples could be devised based on a priori knowledge of different
aspects of the bitstream structure. In all cases, the timing and aspects of the bitstream structure. In all cases, the timing and
congestion control mechanisms of RFC 4585 MUST be observed.</t> congestion control mechanisms of <xref target="RFC4585"/> <bcp14>MUST</bcp14> be
observed.</t>
</section> </section>
<section anchor="FIR"><name>Full Intra Request (FIR)</name> <section anchor="FIR">
<name>Full Intra Request (FIR)</name>
<t>The purpose of the FIR message is to force an encoder to send an <t>The purpose of the FIR message is to force an encoder to send an
independent decoder refresh point as soon as possible, independent decoder refresh point as soon as possible
while observing applicable congestion-control-related constraints, while observing applicable congestion-control-related constraints,
such as those set out in <xref target="RFC8082"/>).</t> such as those set out in <xref target="RFC8082"/>.</t>
<t>Upon reception of a FIR, a sender <bcp14>MUST</bcp14> send an IDR pic
<t>Upon reception of a FIR, a sender MUST send an IDR picture. ture.
Parameter sets MUST also be sent, except when there is a priori Parameter sets <bcp14>MUST</bcp14> also be sent, except when there is a priori
knowledge that the parameter sets have been correctly established. A knowledge that the parameter sets have been correctly established. A
typical example for that is an understanding between sender and typical example for that is an understanding between the sender and
receiver, established by means outside this document, that parameter receiver, established by means outside this document, that parameter
sets are exclusively sent out-of-band.</t> sets are exclusively sent out of band.</t>
</section>
</section> </section>
</section> <section anchor="Security">
<section anchor="Security"><name>Security Considerations</name> <name>Security Considerations</name>
<t>The scope of this section is limited to the
<t>The scope of this Security Considerations section is limited to the
payload format itself and to one feature of <xref target="VVC"/> that may pose a payload format itself and to one feature of <xref target="VVC"/> that may pose a
particularly serious security risk if implemented naively. The particularly serious security risk if implemented naively. The
payload format, in isolation, does not form a complete system. payload format, in isolation, does not form a complete system.
Implementers are advised to read and understand relevant security- Implementers are advised to read and understand relevant security-related docume
related documents, especially those pertaining to RTP (see the nts, especially those pertaining to RTP (see the
Security Considerations section in <xref target="RFC3550"/>), and the security o Security Considerations section in <xref target="RFC3550"/>) and the security of
f
the call-control stack chosen (that may make use of the media type the call-control stack chosen (that may make use of the media type
registration of this memo). Implementers should also consider known registration of this memo). Implementers should also consider known
security vulnerabilities of video coding and decoding implementations security vulnerabilities of video coding and decoding implementations
in general and avoid those.</t> in general and avoid those.</t>
<t>Within this RTP payload format, and with the exception of the user
<t>Within this RTP payload format, and with the exception of the user
data SEI message as described below, no security threats other than data SEI message as described below, no security threats other than
those common to RTP payload formats are known. In other words, those common to RTP payload formats are known. In other words,
neither the various media-plane-based mechanisms, nor the signaling neither the various media-plane-based mechanisms nor the signaling
part of this memo, seems to pose a security risk beyond those common part of this memo seem to pose a security risk beyond those common
to all RTP-based systems.</t> to all RTP-based systems.</t>
<t>RTP packets using the payload format defined in this specification
<t>RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP are subject to the security considerations discussed in the RTP
specification <xref target="RFC3550"/>, and in any applicable RTP profile such a s specification <xref target="RFC3550"/> and in any applicable RTP profile, such a s
RTP/AVP <xref target="RFC3551"/>, RTP/AVPF <xref target="RFC4585"/>, RTP/SAVP <x ref target="RFC3711"/>, RTP/AVP <xref target="RFC3551"/>, RTP/AVPF <xref target="RFC4585"/>, RTP/SAVP <x ref target="RFC3711"/>,
or RTP/SAVPF <xref target="RFC5124"/>. However, as "Securing the RTP Framework: or RTP/SAVPF <xref target="RFC5124"/>. However, as "Securing the RTP Framework:
Why RTP Does Not Mandate a Single Media Security Solution" <xref target="RFC7202 "/> Why RTP Does Not Mandate a Single Media Security Solution" <xref target="RFC7202 "/>
discusses, it is not an RTP payload format's responsibility to discusses, it is not an RTP payload format's responsibility to
discuss or mandate what solutions are used to meet the basic security discuss or mandate what solutions are used to meet the basic security
goals like confidentiality, integrity and source authenticity for RTP goals, like confidentiality, integrity, and source authenticity for RTP
in general. This responsibility lays on anyone using RTP in an in general. This responsibility lays on anyone using RTP in an
application. They can find guidance on available security mechanisms application. They can find guidance on available security mechanisms
and important considerations in "Options for Securing RTP Sessions" and important considerations in "Options for Securing RTP Sessions"
<xref target="RFC7201"/>. The rest of this section discusses the security <xref target="RFC7201"/>. The rest of this section discusses the security
impacting properties of the payload format itself.</t> impacting properties of the payload format itself.</t>
<t>Because the data compression used with this payload format is applied
<t>Because the data compression used with this payload format is applied end to end, any encryption needs to be performed after compression.
end-to-end, any encryption needs to be performed after compression.
A potential denial-of-service threat exists for data encodings using A potential denial-of-service threat exists for data encodings using
compression techniques that have non-uniform receiver-end compression techniques that have non-uniform receiver-end
computational load. The attacker can inject pathological datagrams computational load. The attacker can inject pathological datagrams
into the bitstream that are complex to decode and that cause the into the bitstream that are complex to decode and that cause the
receiver to be overloaded. <xref target="VVC"/> is particularly vulnerable to s uch receiver to be overloaded. <xref target="VVC"/> is particularly vulnerable to s uch
attacks, as it is extremely simple to generate datagrams containing attacks, as it is extremely simple to generate datagrams containing
NAL units that affect the decoding process of many future NAL units. NAL units that affect the decoding process of many future NAL units.
Therefore, the usage of data origin authentication and data integrity Therefore, the usage of data origin authentication and data integrity
protection of at least the RTP packet is RECOMMENDED but NOT REQUIRED, protection of at least the RTP packet is <bcp14>RECOMMENDED</bcp14> but NOT <bcp
based on the thoughts of <xref target="RFC7202"/></t> 14>REQUIRED</bcp14>
based on the thoughts of <xref target="RFC7202"/>.</t>
<t>Like HEVC <xref target="RFC7798"/>, <xref target="VVC"/> includes a user data <t>Like HEVC <xref target="RFC7798"/>, <xref target="VVC"/> includes a use
Supplemental r data Supplemental
Enhancement Information (SEI) message. This SEI message allows Enhancement Information (SEI) message. This SEI message allows
inclusion of an arbitrary bitstring into the video bitstream. Such a inclusion of an arbitrary bitstring into the video bitstream. Such a
bitstring could include JavaScript, machine code, and other active bitstring could include JavaScript, machine code, and other active
content. <xref target="VVC"/> leaves the handling of this SEI message to the content. <xref target="VVC"/> leaves the handling of this SEI message to the
receiving system. In order to avoid harmful side effects of receiving system. In order to avoid harmful side effects of
the user data SEI message, decoder implementations cannot naively the user data SEI message, decoder implementations cannot naively
trust its content. For example, it would be a bad and insecure trust its content. For example, it would be a bad and insecure
implementation practice to forward any JavaScript a decoder implementation practice to forward any JavaScript a decoder
implementation detects to a web browser. The safest way to deal with implementation detects to a web browser. The safest way to deal with
user data SEI messages is to simply discard them, but that can have user data SEI messages is to simply discard them, but that can have
negative side effects on the quality of experience by the user.</t> negative side effects on the quality of experience by the user.</t>
<t>End-to-end security with authentication, integrity, or
<t>End-to-end security with authentication, integrity, or
confidentiality protection will prevent a MANE from performing media- confidentiality protection will prevent a MANE from performing media-
aware operations other than discarding complete packets. In the case aware operations other than discarding complete packets. In the case
of confidentiality protection, it will even be prevented from of confidentiality protection, it will even be prevented from
discarding packets in a media-aware way. To be allowed to perform discarding packets in a media-aware way. To be allowed to perform
such operations, a MANE is required to be a trusted entity that is such operations, a MANE is required to be a trusted entity that is
included in the security context establishment. This on-path inclusion of the MA NE forgoes end-to-end security guarantees for the end points.</t> included in the security context establishment. This on-path inclusion of the MA NE forgoes end-to-end security guarantees for the end points.</t>
</section>
</section> <section anchor="CC">
<section anchor="CC"><name>Congestion Control</name> <name>Congestion Control</name>
<t>Congestion control for RTP SHALL be used in accordance with RTP <t>Congestion control for RTP <bcp14>SHALL</bcp14> be used in accordance w
ith RTP
<xref target="RFC3550"/> and with any applicable RTP profile, e.g., AVP <xref ta rget="RFC3551"/> or AVPF <xref target="RFC4585"/>. <xref target="RFC3550"/> and with any applicable RTP profile, e.g., AVP <xref ta rget="RFC3551"/> or AVPF <xref target="RFC4585"/>.
If best-effort service is being used, an additional requirement is If best-effort service is being used, an additional requirement is
that users of this payload format MUST monitor packet loss to ensure that users of this payload format <bcp14>MUST</bcp14> monitor packet loss to ens ure
that the packet loss rate is within an acceptable range. Packet loss that the packet loss rate is within an acceptable range. Packet loss
is considered acceptable if a TCP flow across the same network path, is considered acceptable if a TCP flow across the same network path
and experiencing the same network conditions, would achieve an and experiencing the same network conditions would achieve an
average throughput, measured on a reasonable timescale, that is not average throughput, measured on a reasonable timescale, that is not
less than all RTP streams combined are achieved. This condition can less than all RTP streams combined are achieved. This condition can
be satisfied by implementing congestion-control mechanisms to adapt be satisfied by implementing congestion-control mechanisms to adapt
the transmission rate, the number of layers subscribed for a layered the transmission rate, by implementing the number of layers subscribed for a lay ered
multicast session, or by arranging for a receiver to leave the multicast session, or by arranging for a receiver to leave the
session if the loss rate is unacceptably high.</t> session if the loss rate is unacceptably high.</t>
<t>The bitrate adaptation necessary for obeying the congestion control
<t>The bitrate adaptation necessary for obeying the congestion control
principle is easily achievable when real-time encoding is used, for principle is easily achievable when real-time encoding is used, for
example, by adequately tuning the quantization parameter. example, by adequately tuning the quantization parameter.
However, when pre-encoded content is being transmitted, bandwidth However, when pre-encoded content is being transmitted, bandwidth
adaptation requires the pre-coded bitstream to be tailored for such adaptation requires the pre-coded bitstream to be tailored for such
adaptivity. The key mechanisms available in <xref target="VVC"/> are temporal adaptivity. The key mechanisms available in <xref target="VVC"/> are temporal
scalability, and spatial/SNR scalability. A media sender can remove scalability and spatial/SNR scalability. A media sender can remove
NAL units belonging to higher temporal sublayers (i.e., those NAL NAL units belonging to higher temporal sublayers (i.e., those NAL
units with a high value of TID) or higher spatio-SNR layers until the sending bi trate drops to units with a high value of TID) or higher spatio-SNR layers until the sending bi trate drops to
an acceptable range.</t> an acceptable range.</t>
<t>The mechanisms mentioned above generally work within a defined profile
<t>The mechanisms mentioned above generally work within a defined profile and le and level;
vel therefore no renegotiation of the channel is required. Only
and, therefore, no renegotiation of the channel is required. Only
when non-downgradable parameters (such as profile) are required to be when non-downgradable parameters (such as profile) are required to be
changed does it become necessary to terminate and restart the RTP changed does it become necessary to terminate and restart the RTP
stream(s). This may be accomplished by using different RTP payload stream(s). This may be accomplished by using different RTP payload
types.</t> types.</t>
<t>MANEs <bcp14>MAY</bcp14> remove certain unusable packets from the RTP s
<t>MANEs MAY remove certain unusable packets from the RTP stream when tream when
that RTP stream was damaged due to previous packet losses. This can that RTP stream was damaged due to previous packet losses. This can
help reduce the network load in certain special cases. For example, help reduce the network load in certain special cases. For example,
MANEs can remove those FUs where the leading FUs belonging to the MANEs can remove those FUs where the leading FUs belonging to the
same NAL unit have been lost or those dependent slice segments when same NAL unit have been lost or those dependent slice segments when
the leading slice segments belonging to the same slice have been the leading slice segments belonging to the same slice have been
lost, because the trailing FUs or dependent slice segments are lost, because the trailing FUs or dependent slice segments are
meaningless to most decoders. MANE can also remove higher temporal meaningless to most decoders. MANE can also remove higher temporal
scalable layers if the outbound transmission (from the MANE's scalable layers if the outbound transmission (from the MANE's
viewpoint) experiences congestion.</t> viewpoint) experiences congestion.</t>
</section>
</section> <section anchor="iana-considerations">
<section anchor="iana-considerations"><name>IANA Considerations</name> <name>IANA Considerations</name>
<t>A new media type has been registered with IANA; see <xref target="opara
<t>A new media type, as specified in <xref target="oparams"/> of this memo, has ms"/>. </t>
been registered with IANA.</t> </section>
</section>
<section anchor="acknowledgements"><name>Acknowledgements</name>
<t>Dr. Byeongdoo Choi is thanked for the video codec related technical
discussion and other aspects in this memo. Xin Zhao and Dr. Xiang Li
are thanked for their contributions on <xref target="VVC"/> specification descri
ptive content.
Spencer Dawkins is thanked for his valuable review comments that led to great
improvements of this memo. Some parts of this specification share text with the
RTP payload
format for HEVC <xref target="RFC7798"/>. We thank the authors of that
specification for their excellent work.</t>
</section>
</middle> </middle>
<back> <back>
<references>
<references title='Normative References'> <name>References</name>
<references>
<reference anchor="VVC" target="http://www.itu.int/rec/T-REC-H.266"> <name>Normative References</name>
<front> <reference anchor="VVC" target="http://www.itu.int/rec/T-REC-H.266">
<title>Versatile Video Coding, ITU-T Recommendation H.266</title> <front>
<author > <title>Versatile Video Coding</title>
<organization></organization> <author>
</author> <organization>ITU-T</organization>
<date year="2020"/> </author>
</front> <date month="April" year="2022"/>
</reference> </front>
<reference anchor="ISO23090-3" target="https://www.iso.org/standard/73022.html"> <seriesInfo name="ITU-T Recommendation" value="H.266"/>
<front> </reference>
<title>Information technology - Coded representation of immersive media Part
3 Versatile Video Coding</title>
<author initials="" surname="ISO/IEC 23090-3" fullname="ISO/IEC&nbsp;23090-3
">
<organization></organization>
</author>
<date year="2021"/>
</front>
</reference>
<reference anchor="VSEI" target="https://www.itu.int/rec/T-REC-H.274">
<front>
<title>Versatile supplemental enhancement information messages for coded vid
eo bitstreams</title>
<author >
<organization></organization>
</author>
<date year="2020"/>
</front>
</reference>
<reference anchor='RFC2119' target='https://www.rfc-editor.org/info/rfc2119'>
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author fullname='S. Bradner' initials='S.' surname='Bradner'><organization/></a
uthor>
<date month='March' year='1997'/>
<abstract><t>In many standards track documents several words are used to signify
the requirements in the specification. These words are often capitalized. This
document defines these words as they should be interpreted in IETF documents.
This document specifies an Internet Best Current Practices for the Internet Comm
unity, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='2119'/>
<seriesInfo name='DOI' value='10.17487/RFC2119'/>
</reference>
<reference anchor='RFC3550' target='https://www.rfc-editor.org/info/rfc3550'>
<front>
<title>RTP: A Transport Protocol for Real-Time Applications</title>
<author fullname='H. Schulzrinne' initials='H.' surname='Schulzrinne'><organizat
ion/></author>
<author fullname='S. Casner' initials='S.' surname='Casner'><organization/></aut
hor>
<author fullname='R. Frederick' initials='R.' surname='Frederick'><organization/
></author>
<author fullname='V. Jacobson' initials='V.' surname='Jacobson'><organization/><
/author>
<date month='July' year='2003'/>
<abstract><t>This memorandum describes RTP, the real-time transport protocol. R
TP provides end-to-end network transport functions suitable for applications tra
nsmitting real-time data, such as audio, video or simulation data, over multicas
t or unicast network services. RTP does not address resource reservation and do
es not guarantee quality-of- service for real-time services. The data transport
is augmented by a control protocol (RTCP) to allow monitoring of the data deliv
ery in a manner scalable to large multicast networks, and to provide minimal con
trol and identification functionality. RTP and RTCP are designed to be independ
ent of the underlying transport and network layers. The protocol supports the u
se of RTP-level translators and mixers. Most of the text in this memorandum is i
dentical to RFC 1889 which it obsoletes. There are no changes in the packet for
mats on the wire, only changes to the rules and algorithms governing how the pro
tocol is used. The biggest change is an enhancement to the scalable timer algori
thm for calculating when to send RTCP packets in order to minimize transmission
in excess of the intended rate when many participants join a session simultaneou
sly. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='STD' value='64'/>
<seriesInfo name='RFC' value='3550'/>
<seriesInfo name='DOI' value='10.17487/RFC3550'/>
</reference>
<reference anchor='RFC3551' target='https://www.rfc-editor.org/info/rfc3551'>
<front>
<title>RTP Profile for Audio and Video Conferences with Minimal Control</title>
<author fullname='H. Schulzrinne' initials='H.' surname='Schulzrinne'><organizat
ion/></author>
<author fullname='S. Casner' initials='S.' surname='Casner'><organization/></aut
hor>
<date month='July' year='2003'/>
<abstract><t>This document describes a profile called &quot;RTP/AVP&quot; for th
e use of the real-time transport protocol (RTP), version 2, and the associated c
ontrol protocol, RTCP, within audio and video multiparticipant conferences with
minimal control. It provides interpretations of generic fields within the RTP s
pecification suitable for audio and video conferences. In particular, this docu
ment defines a set of default mappings from payload type numbers to encodings. T
his document also describes how audio and video data may be carried within RTP.
It defines a set of standard encodings and their names when used within RTP. T
he descriptions provide pointers to reference implementations and the detailed s
tandards. This document is meant as an aid for implementors of audio, video and
other real-time multimedia applications. This memorandum obsoletes RFC 1890. I
t is mostly backwards-compatible except for functions removed because two intero
perable implementations were not found. The additions to RFC 1890 codify existi
ng practice in the use of payload formats under this profile and include new pay
load formats defined since RFC 1890 was published. [STANDARDS-TRACK]</t></abstr
act>
</front>
<seriesInfo name='STD' value='65'/>
<seriesInfo name='RFC' value='3551'/>
<seriesInfo name='DOI' value='10.17487/RFC3551'/>
</reference>
<reference anchor='RFC3711' target='https://www.rfc-editor.org/info/rfc3711'>
<front>
<title>The Secure Real-time Transport Protocol (SRTP)</title>
<author fullname='M. Baugher' initials='M.' surname='Baugher'><organization/></a
uthor>
<author fullname='D. McGrew' initials='D.' surname='McGrew'><organization/></aut
hor>
<author fullname='M. Naslund' initials='M.' surname='Naslund'><organization/></a
uthor>
<author fullname='E. Carrara' initials='E.' surname='Carrara'><organization/></a
uthor>
<author fullname='K. Norrman' initials='K.' surname='Norrman'><organization/></a
uthor>
<date month='March' year='2004'/>
<abstract><t>This document describes the Secure Real-time Transport Protocol (SR
TP), a profile of the Real-time Transport Protocol (RTP), which can provide conf
identiality, message authentication, and replay protection to the RTP traffic an
d to the control traffic for RTP, the Real-time Transport Control Protocol (RTCP
). [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='3711'/>
<seriesInfo name='DOI' value='10.17487/RFC3711'/>
</reference>
<reference anchor='RFC8866' target='https://www.rfc-editor.org/info/rfc8866'>
<front>
<title>SDP: Session Description Protocol</title>
<author fullname='A. Begen' initials='A.' surname='Begen'><organization/></autho
r>
<author fullname='P. Kyzivat' initials='P.' surname='Kyzivat'><organization/></a
uthor>
<author fullname='C. Perkins' initials='C.' surname='Perkins'><organization/></a
uthor>
<author fullname='M. Handley' initials='M.' surname='Handley'><organization/></a
uthor>
<date month='January' year='2021'/>
<abstract><t>This memo defines the Session Description Protocol (SDP). SDP is in
tended for describing multimedia sessions for the purposes of session announceme
nt, session invitation, and other forms of multimedia session initiation. This d
ocument obsoletes RFC 4566.</t></abstract>
</front>
<seriesInfo name='RFC' value='8866'/>
<seriesInfo name='DOI' value='10.17487/RFC8866'/>
</reference>
<reference anchor='RFC4585' target='https://www.rfc-editor.org/info/rfc4585'>
<front>
<title>Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Base
d Feedback (RTP/AVPF)</title>
<author fullname='J. Ott' initials='J.' surname='Ott'><organization/></author>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut
hor>
<author fullname='N. Sato' initials='N.' surname='Sato'><organization/></author>
<author fullname='C. Burmeister' initials='C.' surname='Burmeister'><organizatio
n/></author>
<author fullname='J. Rey' initials='J.' surname='Rey'><organization/></author>
<date month='July' year='2006'/>
<abstract><t>Real-time media streams that use RTP are, to some degree, resilient
against packet losses. Receivers may use the base mechanisms of the Real-time
Transport Control Protocol (RTCP) to report packet reception statistics and thus
allow a sender to adapt its transmission behavior in the mid-term. This is the
sole means for feedback and feedback-based error repair (besides a few codec-sp
ecific mechanisms). This document defines an extension to the Audio-visual Prof
ile (AVP) that enables receivers to provide, statistically, more immediate feedb
ack to the senders and thus allows for short-term adaptation and efficient feedb
ack-based repair mechanisms to be implemented. This early feedback profile (AVP
F) maintains the AVP bandwidth constraints for RTCP and preserves scalability to
large groups. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4585'/>
<seriesInfo name='DOI' value='10.17487/RFC4585'/>
</reference>
<reference anchor='RFC5104' target='https://www.rfc-editor.org/info/rfc5104'>
<front>
<title>Codec Control Messages in the RTP Audio-Visual Profile with Feedback (AVP
F)</title>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut
hor>
<author fullname='U. Chandra' initials='U.' surname='Chandra'><organization/></a
uthor>
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio
n/></author>
<author fullname='B. Burman' initials='B.' surname='Burman'><organization/></aut
hor>
<date month='February' year='2008'/>
<abstract><t>This document specifies a few extensions to the messages defined in
the Audio-Visual Profile with Feedback (AVPF). They are helpful primarily in c
onversational multimedia scenarios where centralized multipoint functionalities
are in use. However, some are also usable in smaller multicast environments and
point-to-point calls.</t><t>The extensions discussed are messages related to th
e ITU-T Rec. H.271 Video Back Channel, Full Intra Request, Temporary Maximum Med
ia Stream Bit Rate, and Temporal-Spatial Trade-off. [STANDARDS-TRACK]</t></abst
ract>
</front>
<seriesInfo name='RFC' value='5104'/>
<seriesInfo name='DOI' value='10.17487/RFC5104'/>
</reference>
<reference anchor='RFC5124' target='https://www.rfc-editor.org/info/rfc5124'>
<front>
<title>Extended Secure RTP Profile for Real-time Transport Control Protocol (RTC
P)-Based Feedback (RTP/SAVPF)</title>
<author fullname='J. Ott' initials='J.' surname='Ott'><organization/></author>
<author fullname='E. Carrara' initials='E.' surname='Carrara'><organization/></a
uthor>
<date month='February' year='2008'/>
<abstract><t>An RTP profile (SAVP) for secure real-time communications and anoth
er profile (AVPF) to provide timely feedback from the receivers to a sender are
defined in RFC 3711 and RFC 4585, respectively. This memo specifies the combina
tion of both profiles to enable secure RTP communications with feedback. [STAND
ARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='5124'/>
<seriesInfo name='DOI' value='10.17487/RFC5124'/>
</reference>
<reference anchor='RFC8174' target='https://www.rfc-editor.org/info/rfc8174'>
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
<author fullname='B. Leiba' initials='B.' surname='Leiba'><organization/></autho
r>
<date month='May' year='2017'/>
<abstract><t>RFC 2119 specifies common key words that may be used in protocol s
pecifications. This document aims to reduce the ambiguity by clarifying that on
ly UPPERCASE usage of the key words have the defined special meanings.</t></abs
tract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='8174'/>
<seriesInfo name='DOI' value='10.17487/RFC8174'/>
</reference>
<reference anchor='RFC8082' target='https://www.rfc-editor.org/info/rfc8082'>
<front>
<title>Using Codec Control Messages in the RTP Audio-Visual Profile with Feedbac
k with Layered Codecs</title>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut
hor>
<author fullname='J. Lennox' initials='J.' surname='Lennox'><organization/></aut
hor>
<author fullname='B. Burman' initials='B.' surname='Burman'><organization/></aut
hor>
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio
n/></author>
<date month='March' year='2017'/>
<abstract><t>This document updates RFC 5104 by fixing a shortcoming in the speci
fication language of the Codec Control Message Full Intra Request (FIR) descript
ion when using it with layered codecs. In particular, a decoder refresh point n
eeds to be sent by a media sender when a FIR is received on any layer of the lay
ered bitstream, regardless of whether those layers are being sent in a single or
in multiple RTP flows. The other payload-specific feedback messages defined in
RFC 5104 and RFC 4585 (which was updated by RFC 5506) have also been analyzed,
and no corresponding shortcomings have been found.</t></abstract>
</front>
<seriesInfo name='RFC' value='8082'/>
<seriesInfo name='DOI' value='10.17487/RFC8082'/>
</reference>
<reference anchor='RFC4556' target='https://www.rfc-editor.org/info/rfc4556'>
<front>
<title>Public Key Cryptography for Initial Authentication in Kerberos (PKINIT)</
title>
<author fullname='L. Zhu' initials='L.' surname='Zhu'><organization/></author>
<author fullname='B. Tung' initials='B.' surname='Tung'><organization/></author>
<date month='June' year='2006'/>
<abstract><t>This document describes protocol extensions (hereafter called PKINI
T) to the Kerberos protocol specification. These extensions provide a method fo
r integrating public key cryptography into the initial authentication exchange,
by using asymmetric-key signature and/or encryption algorithms in pre-authentica
tion data fields. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='4556'/>
<seriesInfo name='DOI' value='10.17487/RFC4556'/>
</reference>
<reference anchor='RFC3264' target='https://www.rfc-editor.org/info/rfc3264'>
<front>
<title>An Offer/Answer Model with Session Description Protocol (SDP)</title>
<author fullname='J. Rosenberg' initials='J.' surname='Rosenberg'><organization/
></author>
<author fullname='H. Schulzrinne' initials='H.' surname='Schulzrinne'><organizat
ion/></author>
<date month='June' year='2002'/>
<abstract><t>This document defines a mechanism by which two entities can make us
e of the Session Description Protocol (SDP) to arrive at a common view of a mult
imedia session between them. In the model, one participant offers the other a d
escription of the desired session from their perspective, and the other particip
ant answers with the desired session from their perspective. This offer/answer
model is most useful in unicast sessions where information from both participant
s is needed for the complete view of the session. The offer/answer model is use
d by protocols like the Session Initiation Protocol (SIP). [STANDARDS-TRACK]</t
></abstract>
</front>
<seriesInfo name='RFC' value='3264'/>
<seriesInfo name='DOI' value='10.17487/RFC3264'/>
</reference>
<reference anchor='RFC4648' target='https://www.rfc-editor.org/info/rfc4648'>
<front>
<title>The Base16, Base32, and Base64 Data Encodings</title>
<author fullname='S. Josefsson' initials='S.' surname='Josefsson'><organization/
></author>
<date month='October' year='2006'/>
<abstract><t>This document describes the commonly used base 64, base 32, and bas
e 16 encoding schemes. It also discusses the use of line-feeds in encoded data,
use of padding in encoded data, use of non-alphabet characters in encoded data,
use of different encoding alphabets, and canonical encodings. [STANDARDS-TRACK
]</t></abstract>
</front>
<seriesInfo name='RFC' value='4648'/>
<seriesInfo name='DOI' value='10.17487/RFC4648'/>
</reference>
<reference anchor='RFC5576' target='https://www.rfc-editor.org/info/rfc5576'>
<front>
<title>Source-Specific Media Attributes in the Session Description Protocol (SDP
)</title>
<author fullname='J. Lennox' initials='J.' surname='Lennox'><organization/></aut
hor>
<author fullname='J. Ott' initials='J.' surname='Ott'><organization/></author>
<author fullname='T. Schierl' initials='T.' surname='Schierl'><organization/></a
uthor>
<date month='June' year='2009'/>
<abstract><t>The Session Description Protocol (SDP) provides mechanisms to descr
ibe attributes of multimedia sessions and of individual media streams (e.g., Rea
l-time Transport Protocol (RTP) sessions) within a multimedia session, but does
not provide any mechanism to describe individual media sources within a media st
ream. This document defines a mechanism to describe RTP media sources, which ar
e identified by their synchronization source (SSRC) identifiers, in SDP, to asso
ciate attributes with these sources, and to express relationships among sources.
It also defines several source-level attributes that can be used to describe p
roperties of media sources. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='5576'/>
<seriesInfo name='DOI' value='10.17487/RFC5576'/>
</reference>
</references>
<references title='Informative References'>
<reference anchor='RFC7656' target='https://www.rfc-editor.org/info/rfc7656'>
<front>
<title>A Taxonomy of Semantics and Mechanisms for Real-Time Transport Protocol (
RTP) Sources</title>
<author fullname='J. Lennox' initials='J.' surname='Lennox'><organization/></aut
hor>
<author fullname='K. Gross' initials='K.' surname='Gross'><organization/></autho
r>
<author fullname='S. Nandakumar' initials='S.' surname='Nandakumar'><organizatio
n/></author>
<author fullname='G. Salgueiro' initials='G.' surname='Salgueiro'><organization/
></author>
<author fullname='B. Burman' initials='B.' role='editor' surname='Burman'><organ
ization/></author>
<date month='November' year='2015'/>
<abstract><t>The terminology about, and associations among, Real-time Transport
Protocol (RTP) sources can be complex and somewhat opaque. This document descri
bes a number of existing and proposed properties and relationships among RTP sou
rces and defines common terminology for discussing protocol entities and their r
elationships.</t></abstract>
</front>
<seriesInfo name='RFC' value='7656'/>
<seriesInfo name='DOI' value='10.17487/RFC7656'/>
</reference>
<reference anchor="CABAC" >
<front>
<title>Transform coefficient coding in HEVC, IEEE Transactions on Circuits a
nd Systems for Video Technology</title>
<author initials="" surname="" fullname="Sole, J">
<organization></organization>
</author>
<author initials="" surname="et al" fullname="et al">
<organization></organization>
</author>
<date year="2012" month="December"/>
</front>
<seriesInfo name="DOI" value="10.1109/TCSVT.2012.2223055"/>
</reference>
<reference anchor="MPEG2S" >
<front>
<title>Information technology - Generic coding of moving pictures and associ
ated audio information - Part 1: Systems, ISO International Standard 13818-1</ti
tle>
<author initials="" surname="IS0/IEC" fullname="IS0/IEC">
<organization></organization>
</author>
<date year="2013"/>
</front>
</reference>
<reference anchor="HEVC" target="https://www.itu.int/rec/T-REC-H.265">
<front>
<title>High efficiency video coding, ITU-T Recommendation H.265</title>
<author >
<organization></organization>
</author>
<date year="2019"/>
</front>
</reference>
<reference anchor='RFC6184' target='https://www.rfc-editor.org/info/rfc6184'>
<front>
<title>RTP Payload Format for H.264 Video</title>
<author fullname='Y.-K. Wang' initials='Y.-K.' surname='Wang'><organization/></a
uthor>
<author fullname='R. Even' initials='R.' surname='Even'><organization/></author>
<author fullname='T. Kristensen' initials='T.' surname='Kristensen'><organizatio
n/></author>
<author fullname='R. Jesup' initials='R.' surname='Jesup'><organization/></autho
r>
<date month='May' year='2011'/>
<abstract><t>This memo describes an RTP Payload format for the ITU-T Recommendat
ion H.264 video codec and the technically identical ISO/IEC International Standa
rd 14496-10 video codec, excluding the Scalable Video Coding (SVC) extension and
the Multiview Video Coding extension, for which the RTP payload formats are def
ined elsewhere. The RTP payload format allows for packetization of one or more N
etwork Abstraction Layer Units (NALUs), produced by an H.264 video encoder, in e
ach RTP payload. The payload format has wide applicability, as it supports appl
ications from simple low bitrate conversational usage, to Internet video streami
ng with interleaved transmission, to high bitrate video-on-demand.</t><t>This me
mo obsoletes RFC 3984. Changes from RFC 3984 are summarized in Section 14. Iss
ues on backward compatibility to RFC 3984 are discussed in Section 15. [STANDAR
DS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6184'/>
<seriesInfo name='DOI' value='10.17487/RFC6184'/>
</reference>
<reference anchor='RFC6190' target='https://www.rfc-editor.org/info/rfc6190'>
<front>
<title>RTP Payload Format for Scalable Video Coding</title>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut
hor>
<author fullname='Y.-K. Wang' initials='Y.-K.' surname='Wang'><organization/></a
uthor>
<author fullname='T. Schierl' initials='T.' surname='Schierl'><organization/></a
uthor>
<author fullname='A. Eleftheriadis' initials='A.' surname='Eleftheriadis'><organ
ization/></author>
<date month='May' year='2011'/>
<abstract><t>This memo describes an RTP payload format for Scalable Video Coding
(SVC) as defined in Annex G of ITU-T Recommendation H.264, which is technically
identical to Amendment 3 of ISO/IEC International Standard 14496-10. The RTP p
ayload format allows for packetization of one or more Network Abstraction Layer
(NAL) units in each RTP packet payload, as well as fragmentation of a NAL unit i
n multiple RTP packets. Furthermore, it supports transmission of an SVC stream o
ver a single as well as multiple RTP sessions. The payload format defines a new
media subtype name &quot;H264-SVC&quot;, but is still backward compatible to RF
C 6184 since the base layer, when encapsulated in its own RTP stream, must use t
he H.264 media subtype name (&quot;H264&quot;) and the packetization method spec
ified in RFC 6184. The payload format has wide applicability in videoconferenci
ng, Internet video streaming, and high-bitrate entertainment-quality video, amon
g others. [STANDARDS-TRACK]</t></abstract>
</front>
<seriesInfo name='RFC' value='6190'/>
<seriesInfo name='DOI' value='10.17487/RFC6190'/>
</reference>
<reference anchor='RFC7201' target='https://www.rfc-editor.org/info/rfc7201'>
<front>
<title>Options for Securing RTP Sessions</title>
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio
n/></author>
<author fullname='C. Perkins' initials='C.' surname='Perkins'><organization/></a
uthor>
<date month='April' year='2014'/>
<abstract><t>The Real-time Transport Protocol (RTP) is used in a large number of
different application domains and environments. This heterogeneity implies tha
t different security mechanisms are needed to provide services such as confident
iality, integrity, and source authentication of RTP and RTP Control Protocol (RT
CP) packets suitable for the various environments. The range of solutions makes
it difficult for RTP-based application developers to pick the most suitable mec
hanism. This document provides an overview of a number of security solutions fo
r RTP and gives guidance for developers on how to choose the appropriate securit
y mechanism.</t></abstract>
</front>
<seriesInfo name='RFC' value='7201'/>
<seriesInfo name='DOI' value='10.17487/RFC7201'/>
</reference>
<reference anchor='RFC7202' target='https://www.rfc-editor.org/info/rfc7202'>
<front>
<title>Securing the RTP Framework: Why RTP Does Not Mandate a Single Media Secur
ity Solution</title>
<author fullname='C. Perkins' initials='C.' surname='Perkins'><organization/></a
uthor>
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio
n/></author>
<date month='April' year='2014'/>
<abstract><t>This memo discusses the problem of securing real-time multimedia se
ssions. It also explains why the Real-time Transport Protocol (RTP) and the ass
ociated RTP Control Protocol (RTCP) do not mandate a single media security mecha
nism. This is relevant for designers and reviewers of future RTP extensions to
ensure that appropriate security mechanisms are mandated and that any such mecha
nisms are specified in a manner that conforms with the RTP architecture.</t></ab
stract>
</front>
<seriesInfo name='RFC' value='7202'/>
<seriesInfo name='DOI' value='10.17487/RFC7202'/>
</reference>
<reference anchor='RFC7798' target='https://www.rfc-editor.org/info/rfc7798'> <reference anchor="ISO23090-3" target="https://www.iso.org/standard/7302
<front> 2.html">
<title>RTP Payload Format for High Efficiency Video Coding (HEVC)</title> <front>
<author fullname='Y.-K. Wang' initials='Y.-K.' surname='Wang'><organization/></a <title>Information technology - Coded representation of immersive me
uthor> dia - Part 3: Versatile video coding</title>
<author fullname='Y. Sanchez' initials='Y.' surname='Sanchez'><organization/></a <author>
uthor> <organization>International Organization for Standardization</orga
<author fullname='T. Schierl' initials='T.' surname='Schierl'><organization/></a nization>
uthor> </author>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut <date month="September" year="2022"/>
hor> </front>
<author fullname='M. M. Hannuksela' initials='M. M.' surname='Hannuksela'><organ <seriesInfo name="ISO/IEC" value="23090-3:2022"/>
ization/></author> </reference>
<date month='March' year='2016'/>
<abstract><t>This memo describes an RTP payload format for the video coding stan
dard ITU-T Recommendation H.265 and ISO/IEC International Standard 23008-2, both
also known as High Efficiency Video Coding (HEVC) and developed by the Joint Co
llaborative Team on Video Coding (JCT-VC). The RTP payload format allows for pa
cketization of one or more Network Abstraction Layer (NAL) units in each RTP pac
ket payload as well as fragmentation of a NAL unit into multiple RTP packets. F
urthermore, it supports transmission of an HEVC bitstream over a single stream a
s well as multiple RTP streams. When multiple RTP streams are used, a single tra
nsport or multiple transports may be utilized. The payload format has wide appl
icability in videoconferencing, Internet video streaming, and high-bitrate enter
tainment-quality video, among others.</t></abstract>
</front>
<seriesInfo name='RFC' value='7798'/>
<seriesInfo name='DOI' value='10.17487/RFC7798'/>
</reference>
<reference anchor='RFC2974' target='https://www.rfc-editor.org/info/rfc2974'> <reference anchor="VSEI" target="https://www.itu.int/rec/T-REC-H.274">
<front> <front>
<title>Session Announcement Protocol</title> <title>Versatile supplemental enhancement information messages for c
<author fullname='M. Handley' initials='M.' surname='Handley'><organization/></a oded video bitstreams</title>
uthor> <author>
<author fullname='C. Perkins' initials='C.' surname='Perkins'><organization/></a <organization>ITU-T</organization>
uthor> </author>
<author fullname='E. Whelan' initials='E.' surname='Whelan'><organization/></aut <date month="May" year="2022"/>
hor> </front>
<date month='October' year='2000'/> <seriesInfo name="ITU-T Recommendation" value="H.274"/>
<abstract><t>This document describes version 2 of the multicast session director </reference>
y announcement protocol, Session Announcement Protocol (SAP), and the related is <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
sues affecting security and scalability that should be taken into account by imp 119.xml"/>
lementors. This memo defines an Experimental Protocol for the Internet communit <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
y.</t></abstract> 550.xml"/>
</front> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
<seriesInfo name='RFC' value='2974'/> 551.xml"/>
<seriesInfo name='DOI' value='10.17487/RFC2974'/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
</reference> 711.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
866.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4
585.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
104.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
124.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
174.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8
082.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.3
264.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4
648.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.5
576.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
656.xml"/>
<reference anchor='RFC7826' target='https://www.rfc-editor.org/info/rfc7826'> <reference anchor="CABAC">
<front> <front>
<title>Real-Time Streaming Protocol Version 2.0</title> <title>Transform coefficient coding in HEVC</title>
<author fullname='H. Schulzrinne' initials='H.' surname='Schulzrinne'><organizat <author>
ion/></author> <organization>Sole, J., et al.</organization>
<author fullname='A. Rao' initials='A.' surname='Rao'><organization/></author> </author>
<author fullname='R. Lanphier' initials='R.' surname='Lanphier'><organization/>< <date year="2012" month="December"/>
/author> </front>
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio <refcontent>IEEE Transactions on Circuits and Systems for Video Technol
n/></author> ogy</refcontent>
<author fullname='M. Stiemerling' initials='M.' role='editor' surname='Stiemerli <seriesInfo name="DOI" value="10.1109/TCSVT.2012.2223055"/>
ng'><organization/></author> </reference>
<date month='December' year='2016'/>
<abstract><t>This memorandum defines the Real-Time Streaming Protocol (RTSP) ver
sion 2.0, which obsoletes RTSP version 1.0 defined in RFC 2326.</t><t>RTSP is an
application-layer protocol for the setup and control of the delivery of data wi
th real-time properties. RTSP provides an extensible framework to enable contro
lled, on-demand delivery of real-time data, such as audio and video. Sources of
data can include both live data feeds and stored clips. This protocol is inten
ded to control multiple data delivery sessions; provide a means for choosing del
ivery channels such as UDP, multicast UDP, and TCP; and provide a means for choo
sing delivery mechanisms based upon RTP (RFC 3550).</t></abstract>
</front>
<seriesInfo name='RFC' value='7826'/>
<seriesInfo name='DOI' value='10.17487/RFC7826'/>
</reference>
<reference anchor='RFC7667' target='https://www.rfc-editor.org/info/rfc7667'> <reference anchor="MPEG2S">
<front> <front>
<title>RTP Topologies</title> <title>Information technology - Generic coding of moving pictures an
<author fullname='M. Westerlund' initials='M.' surname='Westerlund'><organizatio d associated audio information - Part 1: Systems</title>
n/></author> <author>
<author fullname='S. Wenger' initials='S.' surname='Wenger'><organization/></aut <organization>International Organization for Standardization</orga
hor> nization>
<date month='November' year='2015'/> </author>
<abstract><t>This document discusses point-to-point and multi-endpoint topologie <date month="September" year="2022"/>
s used in environments based on the Real-time Transport Protocol (RTP). In parti </front>
cular, centralized topologies commonly employed in the video conferencing indust <seriesInfo name="ISO/IEC" value="13818-1:2022"/>
ry are mapped to the RTP terminology.</t></abstract> </reference>
</front>
<seriesInfo name='RFC' value='7667'/>
<seriesInfo name='DOI' value='10.17487/RFC7667'/>
</reference>
<reference anchor="HEVC" target="https://www.itu.int/rec/T-REC-H.265">
<front>
<title>High efficiency video coding</title>
<author>
<organization>ITU-T</organization>
</author>
<date month="August" year="2021"/>
</front>
<seriesInfo name="ITU-T Recommendation" value="H.265"/>
</reference>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6
184.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6
190.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
201.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
202.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
798.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2
974.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
826.xml"/>
<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.7
667.xml"/>
</references>
</references> </references>
<section anchor="acknowledgements" numbered="false">
<name>Acknowledgements</name>
<t><contact fullname="Dr. Byeongdoo Choi"/> is thanked for the video-codec
-related technical
discussion and other aspects in this memo. <contact fullname="Xin Zhao"/> and <c
ontact fullname="Dr. Xiang Li"/>
are thanked for their contributions on <xref target="VVC"/> specification descri
ptive content.
<contact fullname="Spencer Dawkins"/> is thanked for his valuable review comment
s that led to great
improvements of this memo. Some parts of this specification share text with the
RTP payload
format for HEVC <xref target="RFC7798"/>. We thank the authors of that
specification for their excellent work.</t>
</section>
<section anchor="changehistory"><name>Change History</name> <!-- [rfced]
<t>To RFC Editor: PLEASE REMOVE ThIS SECTION BEFORE PUBLICATION</t> In addition, may we add these to the abbreviations or definitions sections? If
added to definitions, we could use the verbatim definitions from [VVC].
<t>draft-zhao-payload-rtp-vvc-00 ........ initial version</t>
<t>draft-zhao-payload-rtp-vvc-01 ........ editorial clarifications and correctio
ns</t>
<t>draft-ietf-payload-rtp-vvc-00 ........ initial WG draft</t>
<t>draft-ietf-payload-rtp-vvc-01 ........ VVC specification update</t>
<t>draft-ietf-payload-rtp-vvc-02 ........ VVC specification update</t>
<t>draft-ietf-payload-rtp-vvc-03 ........ VVC coding tool introduction update</t
>
<t>draft-ietf-payload-rtp-vvc-04 ........ VVC coding tool introduction update</t
>
<t>draft-ietf-payload-rtp-vvc-05 ........ reference udpate and adding placement
for open issues</t>
<t>draft-ietf-payload-rtp-vvc-06 ........ address editor's note</t>
<t>draft-ietf-payload-rtp-vvc-07 ........ address editor's notes</t>
<t>draft-ietf-payload-rtp-vvc-08 ........ address editor's notes</t>
<t>draft-ietf-payload-rtp-vvc-09 ........ address editor's notes</t>
<t>draft-ietf-payload-rtp-vvc-10 ........ address editor's notes</t> CU - coding unit
<t>draft-ietf-payload-rtp-vvc-11 ........ address editor's notes</t> From [VVC]:
coding unit (CU): A coding block of luma samples, two corresponding coding block
s of chroma samples of a picture that has three sample arrays in the single tree
mode, or a coding block of luma samples of a picture that has three sample arra
ys in the dual tree mode, or two coding blocks of chroma samples of a picture th
at has three sample arrays in the dual tree mode, or a coding block of samples o
f a monochrome picture, and syntax structures used to code the samples.
<t>draft-ietf-payload-rtp-vvc-12 ........ address editor's notes</t> PH - picture header per
<t>draft-ietf-payload-rtp-vvc-13 ........ address editor's notes</t> From [VVC]:
picture header (PH): A syntax structure containing syntax elements that apply to
all slices of a coded picture.
<t>draft-ietf-payload-rtp-vvc-14 ........ address 2nd WGLC comments</t> CTB - coding tree block (note: CTB only appears in the definition for CTU.)
</section> From [VVC]:
coding tree unit (CTU): A CTB of luma samples, two corresponding CTBs of chroma
samples of a picture that has three sample arrays, or a CTB of samples of a mono
chrome picture, and syntax structures used to code the samples.
</back> RBSP - raw byte sequence payload
<!-- ##markdown-source: From [VVC]:
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</back>
</rfc> </rfc>
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