rfc9584.original   rfc9584.txt 
avtcore S. Zhao Internet Engineering Task Force (IETF) S. Zhao
Internet-Draft Intel Request for Comments: 9584 Intel
Intended status: Standards Track S. Wenger Category: Standards Track S. Wenger
Expires: 21 June 2024 Tencent ISSN: 2070-1721 Tencent
Y. Lim Y. Lim
Samsung Electronics Samsung Electronics
19 December 2023 May 2024
RTP Payload Format for Essential Video Coding (EVC) RTP Payload Format for Essential Video Coding (EVC)
draft-ietf-avtcore-rtp-evc-07
Abstract Abstract
This document describes an RTP payload format for the Essential Video This document describes an RTP payload format for the Essential Video
Coding (EVC) standard, published as ISO/IEC International Standard Coding (EVC) standard, published as ISO/IEC International Standard
23094-1. EVC was developed by the Moving Picture Experts Group 23094-1. EVC was developed by the MPEG. The RTP payload format
(MPEG). The RTP payload format allows for the packetization of one allows for the packetization of one or more Network Abstraction Layer
or more Network Abstraction Layer (NAL) units in each RTP packet (NAL) units in each RTP packet payload and the fragmentation of a NAL
payload and the fragmentation of a NAL unit into multiple RTP unit into multiple RTP packets. The payload format has broad
packets. The payload format has broad applicability in applicability in videoconferencing, Internet video streaming, and
videoconferencing, Internet video streaming, and high-bitrate high-bitrate entertainment-quality video, among other applications.
entertainment-quality video, among other applications.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Overview of the EVC Codec . . . . . . . . . . . . . . . . 3 1.1. Overview of the EVC Codec
1.1.1. Coding-Tool Features (informative) . . . . . . . . . 4 1.1.1. Coding-Tool Features (Informative)
1.1.2. Systems and Transport Interfaces . . . . . . . . . . 6 1.1.2. Systems and Transport Interfaces
1.1.3. Parallel Processing Support (informative) . . . . . . 9 1.1.3. Parallel Processing Support (Informative)
1.1.4. NAL Unit Header . . . . . . . . . . . . . . . . . . . 9 1.1.4. NAL Unit Header
1.2. Overview of the Payload Format . . . . . . . . . . . . . 10 1.2. Overview of the Payload Format
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Conventions
3. Definitions and Abbreviations . . . . . . . . . . . . . . . . 11 3. Definitions and Abbreviations
3.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 11 3.1. Definitions
3.1.1. Definitions from the EVC Standard . . . . . . . . . . 11 3.1.1. Definitions from the EVC Standard
3.1.2. Definitions Specific to This Document . . . . . . . . 13 3.1.2. Definitions Specific to This Document
3.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 14 3.2. Abbreviations
4. RTP Payload Format . . . . . . . . . . . . . . . . . . . . . 16 4. RTP Payload Format
4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 16 4.1. RTP Header Usage
4.2. Payload Header Usage . . . . . . . . . . . . . . . . . . 17 4.2. Payload Header Usage
4.3. Payload Structures . . . . . . . . . . . . . . . . . . . 17 4.3. Payload Structures
4.3.1. Single NAL Unit Packets . . . . . . . . . . . . . . . 18 4.3.1. Single NAL Unit Packets
4.3.2. Aggregation Packets (APs) . . . . . . . . . . . . . . 19 4.3.2. Aggregation Packets (APs)
4.3.3. Fragmentation Units . . . . . . . . . . . . . . . . . 23 4.3.3. Fragmentation Units (FUs)
4.4. Decoding Order Number . . . . . . . . . . . . . . . . . . 26 4.4. Decoding Order Number
5. Packetization Rules . . . . . . . . . . . . . . . . . . . . . 27 5. Packetization Rules
6. De-packetization Process . . . . . . . . . . . . . . . . . . 28 6. De-packetization Process
7. Payload Format Parameters . . . . . . . . . . . . . . . . . . 30 7. Payload Format Parameters
7.1. Media Type Registration . . . . . . . . . . . . . . . . . 30 7.1. Media Type Registration
7.2. Optional Parameters Definition . . . . . . . . . . . . . 31 7.2. Optional Parameters Definition
7.3. SDP Parameters . . . . . . . . . . . . . . . . . . . . . 35 7.3. SDP Parameters
7.3.1. Mapping of Payload Type Parameters to SDP . . . . . . 35 7.3.1. Mapping of Payload Type Parameters to SDP
7.3.2. Usage with SDP Offer/Answer Model . . . . . . . . . . 37 7.3.2. Usage with SDP Offer/Answer Model
7.3.3. Multicast . . . . . . . . . . . . . . . . . . . . . . 41 7.3.3. Multicast
7.3.4. Usage in Declarative Session Descriptions . . . . . . 42 7.3.4. Usage in Declarative Session Descriptions
7.3.5. Considerations for Parameter Sets . . . . . . . . . . 43 7.3.5. Considerations for Parameter Sets
8. Use with Feedback Messages . . . . . . . . . . . . . . . . . 43 8. Use with Feedback Messages
8.1. Picture Loss Indication (PLI) . . . . . . . . . . . . . . 43 8.1. Picture Loss Indication (PLI)
8.2. Full Intra Request (FIR) . . . . . . . . . . . . . . . . 44 8.2. Full Intra Request (FIR)
9. Security Considerations . . . . . . . . . . . . . . . . . . . 44 9. Security Considerations
10. Congestion Control . . . . . . . . . . . . . . . . . . . . . 46 10. Congestion Control
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 11. IANA Considerations
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 47 12. References
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 47 12.1. Normative References
13.1. Normative References . . . . . . . . . . . . . . . . . . 47 12.2. Informative References
13.2. Informative References . . . . . . . . . . . . . . . . . 49 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 50 Authors' Addresses
1. Introduction 1. Introduction
The Essential Video Coding [EVC] standard, which is formally The Essential Video Coding [EVC] standard, which is formally
designated as ISO/IEC International Standard 23094-1 [ISO23094-1] has designated as ISO/IEC International Standard 23094-1 [ISO23094-1],
been published in 2020. One goal of MPEG is to keep [EVC]'s Baseline was published in 2020. One of MPEG's goals is to keep EVC's Baseline
profile essentially royalty-free by using technologies published more profile essentially royalty-free by using technologies published more
than 20 years ago or otherwise known to be available for use without than 20 years ago or otherwise known to be available for use without
a requirement for paying royalties, whereas more advanced profiles a requirement for paying royalties, whereas more advanced profiles
follow a reasonable and non-discriminatory licensing terms policy. follow a reasonable and non-discriminatory licensing terms policy.
Both the Baseline profile and higher profiles of [EVC] are reported Both the Baseline profile and higher profiles of EVC [EVC] are
to provide coding efficiency gains over High Efficiency Video Coding reported to provide coding efficiency gains over High Efficiency
[HEVC] and Advanced Video Coding [AVC] under certain configurations. Video Coding [HEVC] and Advanced Video Coding [AVC] under certain
configurations.
This document describes an RTP payload format for EVC. It shares its This document describes an RTP payload format for EVC. It shares its
basic design with the NAL unit-based RTP payload formats of H.264 basic design with the NAL unit-based RTP payload formats of H.264
Video Coding [RFC6184], Scalable Video Coding (SVC) [RFC6190], High Video Coding [RFC6184], Scalable Video Coding (SVC) [RFC6190], High
Efficiency Video Coding (HEVC) [RFC7798], and Versatile Video Coding Efficiency Video Coding (HEVC) [RFC7798], and Versatile Video Coding
(VVC)[RFC9328]. With respect to design philosophy, security, (VVC) [RFC9328]. With respect to design philosophy, security,
congestion control, and overall implementation complexity, it has congestion control, and overall implementation complexity, it has
similar properties to those earlier payload format specifications. similar properties to those earlier payload format specifications.
This is a conscious choice, as at least [RFC6184] is widely deployed This is a conscious choice, as at least [RFC6184] is widely deployed
and generally known in the relevant implementer communities. Certain and generally known in the relevant implementer communities. Certain
mechanisms known from [RFC6190] were incorporated as EVC supports mechanisms described in [RFC6190] were incorporated, as EVC supports
temporal scalability. EVC currently does not offer higher forms of temporal scalability. EVC currently does not offer higher forms of
scalability. scalability.
1.1. Overview of the EVC Codec 1.1. Overview of the EVC Codec
[EVC], [AVC], [HEVC] and [VVC] share a similar hybrid video codec [EVC], [AVC], [HEVC], and [VVC] share a similar hybrid video codec
design. In this document, we provide a very brief overview of those design. In this document, we provide a very brief overview of those
features of EVC that are, in some form, addressed by the payload features of EVC that are, in some form, addressed by the payload
format specified herein. Implementers have to read, understand, and format specified herein. Implementers have to read, understand, and
apply the ISO/IEC standard pertaining to EVC to arrive at apply the ISO/IEC standard pertaining to EVC [EVC] to arrive at
interoperable, well-performing implementations. The EVC standard has interoperable, well-performing implementations. The EVC standard has
a Baseline profile and a Main profile, the latter being a superset of a Baseline profile and a Main profile, the latter being a superset of
the Baseline profile but including more advanced features. EVC also the Baseline profile but including more advanced features. EVC also
includes still image variants of both Baseline and Main profiles, in includes still image variants of both Baseline and Main profiles, in
each of which the bitstream is restricted to a single IDR picture. each of which the bitstream is restricted to a single IDR picture.
EVC facilitates certain walled-garden implementations under EVC facilitates certain walled garden implementations under
commercial constraints imposed by intellectual property rights by commercial constraints imposed by intellectual property rights by
including syntax elements that allow encoders to mark a bitstream as including syntax elements that allow encoders to mark a bitstream as
to what of the many independent coding tools are exercised in the to what of the many independent coding tools are exercised in the
bitstream, in a spirit similar to the general_constraint_flags of bitstream, in a spirit similar to the general_constraint_flags of
[VVC]. [VVC].
Conceptually, all EVC, AVC, HEVC and VVC include a Video Coding Layer Conceptually, all EVC, AVC, HEVC, and VVC include a Video Coding
(VCL); a term that is often used to refer to the coding-tool Layer (VCL), a term that is often used to refer to the coding-tool
features, and a Network Abstraction Layer (NAL), which usually refers features, and a Network Abstraction Layer (NAL), which usually refers
to the systems and transport interface aspects of the codecs. to the systems and transport interface aspects of the codecs.
1.1.1. Coding-Tool Features (informative) 1.1.1. Coding-Tool Features (Informative)
Coding blocks and transform structure Coding blocks and transform structure
EVC uses a traditional block-based coding structure, which divides
the encoded image into blocks of up to 64x64 luma samples for the
Baseline profile and 128x128 luma samples for the Main profile
that can be recursively divided into smaller blocks. The Baseline
profiles utilize HEVC-like quad-tree blocks partitioning that
allows to divide a block horizontally and vertically onto four
smaller square blocks. The Main profile adds two advanced coding
structure tools: 1) Binary Ternary Tree (BTT) partitioning that
allows non-square coding units and 2) Split Unit Coding Order
segmentation that changes the processing order of the blocks from
traditional left-to-right and top-to-bottom scanning order
processing to an alternative right-to-left and bottom-to-top
scanning order. In the Main profile, the picture can be divided
into slices and tiles, which can be independently encoded and/or
decoded in parallel.
EVC uses a traditional block-based coding structure, which divides EVC also uses a traditional video codecs prediction model assuming
the encoded image into blocks of up to 64x64 luma samples for the two general types of predictions: Intra (spatial) and Inter
Baseline profile and 128x128 luma samples for the Main profile that (temporal) predictions. A residue block is calculated by
can be recursively divided into smaller blocks. The baseline subtracting predicted data from the original (encoded) one. The
profiles utilize an HEVC-like quad-tree blocks partitioning that Baseline profile allows only discrete cosine transform (DCT-2) and
allows to divide a block horizontally and vertically onto four scalar quantization to transform and quantize residue data,
smaller square blocks. The Main profile adds two advanced coding wherein the Main profile additionally has options to use discrete
structure tools: 1) Binary Ternary Tree (BTT) partitioning that sine transform (DST-7) and another type of discrete cosine
allows non-square coding units; and 2) Split Unit Coding Order transform (DCT-8). In addition, for the Main profile, Improved
segmentation that changes the processing order of the blocks from Quantization and Transform (IQT) uses a different mapping/clipping
traditional left-to-right and top-to-bottom scanning order processing function for quantization. An inverse zig-zag scanning order is
to an alternative right-to-left and bottom-to-top scanning order. In used for coefficient coding. Advanced Coefficient Coding (ADCC)
the Main profile, the picture can be divided into slices and tiles, in the Main profile can code coefficient values more efficiently,
which can be independently encoded and/or decoded in parallel. for example, indicated by the last non-zero coefficient. The
Baseline profile uses a straightforward RLE-based approach to
EVC also uses a traditional video codecs prediction model assuming encode the quantized coefficients.
two general types of predictions: Intra (spatial) and Inter
(temporal) predictions. A residue block is calculated by subtracting
predicted data from the original (encoded) one. The Baseline profile
allows only discrete cosine transform (DCT-2) and scalar quantization
to transform and quantize residue data, wherein the Main profile
additionally has options to use discrete sine transform (DST-7) and
another type of discrete cosine transform (DCT-8). In addition, for
the Main profile, Improved Quantization and Transform (IQT) uses a
different mapping/clipping function for quantization. An inverse
zig-zag scanning order is used for coefficient coding. Advanced
Coefficient Coding (ADCC) in the Main profile can code coefficient
values more efficiently, for example, indicated by the last non-zero
coefficient. The Baseline profile uses a straightforward run-length
encoding (RLE) based approach to encode the quantized coefficients.
Entropy coding Entropy coding
EVC uses a similar binary arithmetic coding mechanism as HEVC CABAC EVC uses a similar binary arithmetic coding mechanism as HEVC
and VVC. The mechanism includes a binarization step and a CABAC and VVC. The mechanism includes a binarization step and a
probability update defined by a lookup table. In the Main profile, probability update defined by a lookup table. In the Main
the derivation process of syntax elements based on adjacent blocks profile, the derivation process of syntax elements based on
makes the context modeling and initialization process more efficient. adjacent blocks makes the context modeling and initialization
process more efficient.
In-loop filtering In-loop filtering
The Baseline profile of EVC uses the deblocking filter defined in
The Baseline profile of EVC uses the deblocking filter defined in H.263 Annex J. In the Main profile, an Advanced Deblocking Filter
H.263 Annex J. In the Main profile, an Advanced Deblocking Filter (ADDB) can be used as an alternative, which can further reduce
(ADDB) can be used as an alternative, which can further reduce undesirable compression artifacts. The Main profile also defines
undesirable compression artifacts. The Main profile also defines two two additional in-loop filters that can be used to improve the
additional in-loop filters that can be used to improve the quality of quality of decoded pictures before output and/or for inter-
decoded pictures before output and/or for inter-prediction. A prediction. A Hadamard Transform Domain Filter (HTDF) is applied
Hadamard Transform Domain Filter (HTDF) is applied to the luma to the luma samples before deblocking, and a lookup table is used
samples before deblocking, and a lookup table is used to determine to determine four adjacent samples for filtering. An adaptive
four adjacent samples for filtering. An adaptive Loop Filter (ALF) Loop Filter (ALF) allows to send signals of up to 25 different
allows to send signals of up to 25 different filters for the luma filters for the luma components, and the best filter can be
components, and the best filter can be selected through the selected through the classification process for each 4x4 block.
classification process for each 4x4 block. Similarly to VVC, the Similarly to VVC, the filter parameters of ALF are signaled in the
filter parameters of ALF are signaled in the Adaptation Parameter Set Adaptation Parameter Set (APS).
(APS).
Inter-prediction Inter-prediction
The basis of EVC's inter-prediction is motion compensation using
The basis of EVC's inter-prediction is motion compensation using interpolation filters with a quarter sample resolution. In the
interpolation filters with a quarter sample resolution. In the Baseline profile, a motion vector is transmitted using one of
Baseline profile, a motion vector is transmitted using one of three three spatially neighboring motion vectors and a temporally
spatially neighboring motion vectors and a temporally collocated collocated motion vector as a predictor. A motion vector
motion vector as a predictor. A motion vector difference may be difference may be signaled relative to the selected predictor, but
signaled relative to the selected predictor, but there is a case there is a case where no motion vector difference is signaled, and
where no motion vector difference is signaled, and there is no there is no remaining data in the block. This mode is called a
remaining data in the block. This mode is called a skip mode. The "skip" mode. The Main profile includes six additional tools to
Main profile includes six additional tools to provide improved inter- provide improved inter-prediction. With Advanced Motion Vectors
prediction. With Advanced Motion Vectors Prediction (ADMVP), Prediction (ADMVP), adjacent blocks can be conceptually merged to
adjacent blocks can be conceptually merged to indicate that they use indicate that they use the same motion, but more advanced schemes
the same motion, but more advanced schemes can also be used to create can also be used to create predictions from the basic model list
predictions from the basic model list of candidate predictors. The of candidate predictors. The Merge with Motion Vector Difference
Merge with Motion Vector Difference (MMVD) tool uses a process (MMVD) tool uses a process similar to the concept of merging
similar to the concept of merging neighboring blocks but also allows neighboring blocks but also allows the use of expressions that
the use of expressions that include a starting point, motion include a starting point, motion amplitude, and direction of
amplitude, and direction of motion to send a motion vector signal. motion to send a motion vector signal. Using Advanced Motion
Using Advanced Motion Vector Prediction (AMVP), candidate motion Vector Prediction (AMVP), candidate motion vector predictions for
vector predictions for the block can be derived from its neighboring the block can be derived from its neighboring blocks in the same
blocks in the same picture and collocated blocks in the reference picture and collocated blocks in the reference picture. The
picture. The Adaptive Motion Vector Resolution (AMVR) tool provides Adaptive Motion Vector Resolution (AMVR) tool provides a way to
a way to reduce the accuracy of a motion vector from a quarter sample reduce the accuracy of a motion vector from a quarter sample to
to half sample, full sample, double sample, or quad sample, which half sample, full sample, double sample, or quad sample, which
provides an efficiency advantage, such as when sending large motion provides an efficiency advantage, such as when sending large
vector differences. The Main profile also includes the Decoder-side motion vector differences. The Main profile also includes the
Motion Vector Refinement (DMVR), which uses a bilateral template Decoder-side Motion Vector Refinement (DMVR), which uses a
matching process to refine the motion vectors without additional bilateral template matching process to refine the motion vectors
signaling. without additional signaling.
Intra prediction and intra-coding Intra prediction and intra-coding
Intra prediction in EVC is performed on adjacent samples of coding
Intra prediction in EVC is performed on adjacent samples of coding units in a partitioned structure. For the Baseline profile, when
units in a partitioned structure. For the Baseline profile, when all all coding units are square, there are five different prediction
coding units are square, there are five different prediction modes: modes: DC (mean value of the neighborhood), horizontal, vertical,
DC (mean value of the neighborhood), horizontal, vertical, and two and two different diagonal directions. In the Main profile, intra
different diagonal directions. In the Main profile, intra prediction prediction can be applied to any rectangular coding unit, and 28
can be applied to any rectangular coding unit, and 28 additional additional direction modes are available in the Enhanced Intra
direction modes are available in the so-called Enhanced Intra Prediction Directions (EIPDs). In the Main profile, an encoder
Prediction Directions (EIPD). In the Main profile, an encoder can can also use Intra Block Copy (IBC), where previously decoded
also use Intra Block Copy (IBC), where previously decoded sample sample blocks of the same picture are used as a predictor. A
blocks of the same picture are used as a predictor. A displacement displacement vector in integer sample precision is signaled to
vector in integer sample precision is signaled to indicate where the indicate where the prediction block in the current picture is used
prediction block in the current picture is used for this mode. for this mode.
Reference frames management Reference frames management
In EVC, decoded pictures can be stored in a decoded picture buffer
In EVC, decoded pictures can be stored in a decoded picture buffer (DPB) for predicting pictures that follow them in the decoding
(DPB) for predicting pictures that follow them in the decoding order. order. In the Baseline profile, the management of the DPB (i.e.,
In the Baseline profile, the management of the DPB (i.e., the process the process of adding and deleting reference pictures) is
of adding and deleting reference pictures) is controlled by a controlled by a straightforward AVC-like sliding window approach
straightforward AVC-like sliding window approach with very few with very few parameters from the sequence parameter set (SPS).
parameters from the SPS. For the Main profile, DPB management can be For the Main profile, DPB management can be handled much more
handled much more flexibly using explicitly signaled reference flexibly using explicitly signaled Reference Picture Lists (RPLs)
Picture Lists (RPL) in the SPS or slice level. in the SPS or slice level.
1.1.2. Systems and Transport Interfaces 1.1.2. Systems and Transport Interfaces
EVC inherits the basic systems and transport interface designs from EVC inherits the basic systems and transport interface designs from
AVC and HEVC. These include the NAL-unit-based syntax, hierarchical AVC and HEVC. These include the NAL-unit-based syntax, hierarchical
syntax and data unit structure, and Supplemental Enhancement syntax and data unit structure, and Supplemental Enhancement
Information (SEI) message mechanism. The hierarchical syntax and Information (SEI) message mechanism. The hierarchical syntax and
data unit structure consists of a sequence-level parameter set (SPS), data unit structure consists of a sequence-level parameter set (i.e.,
two picture-level parameter sets (PPS and APS, each of which can SPS), two picture-level parameter sets (i.e., PPS and APS, each of
apply to one or more pictures), slice-level header parameters, and which can apply to one or more pictures), slice-level header
lower-level parameters. parameters, and lower-level parameters.
A number of key components that influenced the Network Abstraction A number of key components that influenced the NAL design of EVC as
Layer design of EVC as well as this document, are described below: well as this document are described below:
Sequence parameter set Sequence parameter set
The Sequence Parameter Set (SPS) contains syntax elements The Sequence Parameter Set (SPS) contains syntax elements
pertaining to a Coded Video Sequence (CVS), which is a group of pertaining to a Coded Video Sequence (CVS), which is a group of
pictures, starting with a random access point picture and followed pictures, starting with a random access point picture and followed
by zero or more pictures that may depend on each other and the by zero or more pictures that may depend on each other and the
random access point picture. In MPEG-2, the equivalent of a CVS random access point picture. In MPEG-2, the equivalent of a CVS
is a Group of Pictures (GOP), which generally started with an I is a Group of Pictures (GOP), which generally starts with an I
frame and is followed by P and B frames. While more complex in frame and is followed by P and B frames. While more complex in
its options of random access points, EVC retains this basic its options of random access points, EVC retains this basic
concept. In many TV-like applications, a CVS contains a few concept. In many TV-like applications, a CVS contains a few
hundred milliseconds to a few seconds of video. In video hundred milliseconds to a few seconds of video. In video
conferencing (without switching MCUs involved), a CVS can be as conferencing (without switching MCUs involved), a CVS can be as
long in duration as the whole session. long in duration as the whole session.
Picture and adaptation parameter set Picture and adaptation parameter set
The Picture Parameter Set (PPS) and the Adaptation Parameter Set
The Picture Parameter Set and the Adaptation Parameter Set (PPS (APS) carry information pertaining to a single picture. The PPS
and APS, respectively) carry information pertaining to a single contains information that is likely to stay constant from picture
picture. The PPS contains information that is likely to stay to picture, at least for pictures of a certain type; whereas the
constant from picture to picture, at least for pictures of a APS contains information, such as adaptive loop filter
certain type whereas the APS contains information, such as coefficients, that are likely to change from picture to picture.
adaptive loop filter coefficients, that are likely to change from
picture to picture.
Profile, level, and toolsets Profile, level, and toolsets
Profiles and levels follow the same design considerations known Profiles and levels follow the same design considerations known
from AVC, HEVC, and video codecs as old as MPEG-1 Video. The from AVC, HEVC, and video codecs as old as MPEG-1 Video. The
profile defines a set of tools (not to confuse with the "toolset" profile defines a set of tools (not to be confused with the
discussed below) that a decoder compliant with this profile has to "toolset" discussed below) that a decoder compliant with this
support. In EVC, profiles are defined in Annex A. Formally, they profile has to support. In EVC, profiles are defined in Annex A
are defined as a set of constraints that a bitstream needs to of [EVC]. Formally, they are defined as a set of constraints that
conform to. In EVC, the Baseline profile is much more severely a bitstream needs to conform to. In EVC, the Baseline profile is
constraint than the Main profile, reducing implementation much more severely constrained than the Main profile, reducing
complexity. Levels relate to bitstream complexity in dimensions implementation complexity. Levels relate to bitstream complexity
such as maximum sample decoding rate, maximum picture size, and in dimensions such as maximum sample decoding rate, maximum
similar parameters directly related to computational complexity picture size, and similar parameters directly related to
and/or memory demands. computational complexity and/or memory demands.
Profiles and levels are signaled in the highest parameter set Profiles and levels are signaled in the highest parameter set
available, the SPS. available, the SPS.
EVC contains another mechanism related to the use of coding tools, EVC contains another mechanism related to the use of coding tools,
known as the toolset syntax element. This syntax element, known as the toolset syntax element. This syntax element,
toolset_idc_h and toolset_idc_l located in the SPS, is a bitmask toolset_idc_h and toolset_idc_l (located in the SPS), is a bitmask
that allows encoders to indicate which coding tools they are using that allows encoders to indicate which coding tools they are using
within the menu of profiles offered by the profile that is also within the menu of profiles offered by the profile that is also
signaled. No decoder conformance point is associated with the signaled. No decoder conformance point is associated with the
toolset, but a bitstream that was using a coding tool that is toolset, but a bitstream that was using a coding tool that is
indicated as not being used in the toolset syntax element would be indicated as not being used in the toolset syntax element would be
non-compliant. While MPEG specifically rules out the use of the non-compliant. While MPEG specifically rules out the use of the
toolset syntax element as a conformance point, walled garden toolset syntax element as a conformance point, walled garden
implementations could do so without incurring the interoperability implementations could do so without incurring the interoperability
problems MPEG fears and create bitstreams and decoders that do not problems MPEG fears and create bitstreams and decoders that do not
support one or more given tools. That, in turn, may be useful to support one or more given tools. That, in turn, may be useful to
skipping to change at page 8, line 13 skipping to change at line 335
toolset, but a bitstream that was using a coding tool that is toolset, but a bitstream that was using a coding tool that is
indicated as not being used in the toolset syntax element would be indicated as not being used in the toolset syntax element would be
non-compliant. While MPEG specifically rules out the use of the non-compliant. While MPEG specifically rules out the use of the
toolset syntax element as a conformance point, walled garden toolset syntax element as a conformance point, walled garden
implementations could do so without incurring the interoperability implementations could do so without incurring the interoperability
problems MPEG fears and create bitstreams and decoders that do not problems MPEG fears and create bitstreams and decoders that do not
support one or more given tools. That, in turn, may be useful to support one or more given tools. That, in turn, may be useful to
mitigate certain intellectual property-related risks. mitigate certain intellectual property-related risks.
Bitstream and elementary stream Bitstream and elementary stream
Above the Coded Video Sequence (CVS), EVC defines a video Above the Coded Video Sequence (CVS), EVC defines a video
bitstream that can be used as an elementary stream in the MPEG bitstream that can be used as an elementary stream in the MPEG
systems context. For this document, the video bitstream syntax systems context. For this document, the video bitstream syntax
level is not relevant. level is not relevant.
Random access support Random access support
EVC supports random access mechanisms based on IDR and CRA access EVC supports random access mechanisms based on IDR and CRA access
units. units.
Temporal scalability support Temporal scalability support
EVC supports temporal scalability through the generalized EVC supports temporal scalability through the generalized
reference picture selection approach known since AVC/SVC. Up to reference picture selection approach known since AVC/SVC. Up to
six temporal layers are supported. The temporal layer is signaled six temporal layers are supported. The temporal layer is signaled
in the NAL unit header (which co-serves as the payload header in in the NAL unit header (which co-serves as the payload header in
this document), in the nuh_temporal_id field. this document), in the nuh_temporal_id field.
Reference picture management Reference picture management
EVC's reference picture management is POC-based, similar to HEVC.
EVC's reference picture management is POC-based (Picture Order In the Main profile, substantially all reference picture list
Count), similar to HEVC. In the Main profile, substantially all manipulations available in HEVC are available, including explicit
reference picture list manipulations available in HEVC are transmissions/updates of reference picture lists. Although for
available, including explicit transmissions/updates of reference reference pictures management purposes, EVC uses a modern VVC-like
picture lists, although for reference pictures management RPL approach, which is conceptually simpler than the HEVC one. In
purposes, EVC uses a modern VVC-like RPL approach, which is the Baseline profile, reference picture management is more
conceptually simpler than the HEVC one. In the Baseline profile, restricted, allowing for a comparatively simple group of picture
reference picture management is more restricted, allowing for a structures only.
comparatively simple group of picture structures only.
SEI Message SEI Message
EVC inherits many of HEVC's SEI messages, occasionally with syntax
EVC inherits many of HEVC's SEI Messages, occasionally with syntax
and/or semantics changes, making them applicable to EVC. In and/or semantics changes, making them applicable to EVC. In
addition, some of the codec-agnostic SEI Messages of the VSEI addition, some of the codec-agnostic SEI messages of the VSEI
specification are also mapped. specification [VSEI] are also mapped.
1.1.3. Parallel Processing Support (informative) 1.1.3. Parallel Processing Support (Informative)
EVC's Baseline profile includes no tools specifically addressing EVC's Baseline profile includes no tools specifically addressing
parallel processing support. The Main profile includes parallel-processing support. The Main profile includes independently
independently decodable slices for parallel processing. The decodable slices for parallel processing. The slices are defined as
slices are defined as any rectangular region within a picture and any rectangular region within a picture and can be encoded to have no
can be encoded to have no coding dependencies with other slices in coding dependencies with other slices in the same picture but with
the same picture but with other slices from the previous picture. other slices from the previous picture. No specific support for
No specific support for parallel processing is specified in this parallel processing is specified in this RTP payload format.
RTP payload format.
1.1.4. NAL Unit Header 1.1.4. NAL Unit Header
EVC maintains the NAL unit concept of [VVC] with different parameter EVC maintains the NAL unit concept of [VVC] with different parameter
options. EVC also uses a two-byte NAL unit header, as shown in options. EVC also uses a two-byte NAL unit header, as shown in
Figure 1. The payload of a NAL unit refers to the NAL unit excluding Figure 1. The payload of a NAL unit refers to the NAL unit excluding
the NAL unit header. the NAL unit header.
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| Type | TID | Reserve |E| |F| Type | TID | Reserve |E|
+-------------+-----------------+ +-------------+-----------------+
The Structure of the EVC NAL Unit Header Figure 1: The Structure of the EVC NAL Unit Header
Figure 1
The semantics of the fields in the NAL unit header are as specified The semantics of the fields in the NAL unit header are as specified
in EVC and described briefly below for convenience. In addition to in EVC 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 EVC is also provided. name in EVC is also provided.
F: 1 bit F: 1 bit
forbidden_zero_bit. Required to be zero in EVC. Note that the forbidden_zero_bit: Required to be zero in EVC. Note that the
inclusion of this bit in the NAL unit header was included to inclusion of this bit in the NAL unit header was included to
enable transport of EVC video over MPEG-2 transport systems enable transport of EVC video over MPEG-2 transport systems
(avoidance of start code emulations) [MPEG2S]. In this document, (avoidance of start code emulations) [MPEG2S]. In this
the value 1 may be used to indicate a syntax violation, e.g., for document, the value 1 may be used to indicate a syntax
a NAL unit resulting from aggregating a number of fragmented units violation, e.g., for a NAL unit resulting from aggregating a
of a NAL unit but missing the last fragment, as described in number of fragmented units of a NAL unit but missing the last
Section 4.3.3. fragment, as described in Section 4.3.3.
Type: 6 bits Type: 6 bits
nal_unit_type_plus1. This field allows the NAL Unit Type to be nal_unit_type_plus1: This field allows the NAL Unit Type to be
computed. The NAL Unit Type (NalUnitType) is equal to the value computed. The NAL Unit Type (NalUnitType) is equal to the
found in this field, minus 1; in other words: value found in this field, minus 1; in other words:
NalUnitType = nal_unit_type_plus1 - 1. NalUnitType = nal_unit_type_plus1 - 1.
The NAL unit type is detailed in Table 4 of [EVC]. If the value The NAL unit type is detailed in Table 4 of [EVC]. If the
of NalUnitType is less than or equal to 23, the NAL unit is a VCL value of NalUnitType is less than or equal to 23, the NAL unit
NAL unit. Otherwise, the NAL unit is a non-VCL NAL unit. For a is a VCL NAL unit. Otherwise, the NAL unit is a non-VCL NAL
reference of all currently defined NAL unit types and their unit. For a reference of all currently defined NAL unit types
semantics, please refer to Section 7.4.2.2 in [EVC]. Note that and their semantics, please refer to Section 7.4.2.2 of [EVC].
nal_unit_type_plus1 MUST NOT be zero. Note that nal_unit_type_plus1 MUST NOT be zero.
TID: 3 bits TID: 3 bits
nuh_temporal_id. This field specifies the temporal identifier of nuh_temporal_id: This field specifies the temporal identifier of
the NAL unit. The value of TemporalId is equal to TID. the NAL unit. The value of TemporalId is equal to TID.
TemporalId shall be equal to 0 if it is an IDR NAL unit type (NAL TemporalId shall be equal to 0 if it is an IDR NAL unit type
unit type 1). (NAL unit type 1).
Reserve: 5 bits Reserve: 5 bits
nuh_reserved_zero_5bits. This field shall be equal to the version nuh_reserved_zero_5bits: This field shall be equal to the version
of the EVC standard. Values of nuh_reserved_zero_5bits greater of the EVC standard. Values of nuh_reserved_zero_5bits greater
than 0 are reserved for future use by ISO/IEC. Decoders than 0 are reserved for future use by ISO/IEC. Decoders
conforming to a profile specified in [EVC]'s Annex A shall ignore conforming to a profile specified in Annex A of [EVC] shall
(i.e., remove from the bitstream and discard) all NAL units with ignore (i.e., remove from the bitstream and discard) all NAL
values of nuh_reserved_zero_5bits greater than 0. units with values of nuh_reserved_zero_5bits greater than 0.
E: 1 bit E: 1 bit
nuh_extension_flag. This field shall be equal to the version of nuh_extension_flag: This field shall be equal to the version of
the EVC standard. The value of nuh_extension_flag equal to 1 is the EVC standard. The value of nuh_extension_flag equal to 1
reserved for future use by ISO/IEC. Decoders conforming to a is reserved for future use by ISO/IEC. Decoders conforming to
profile specified in [EVC]'s Annex A shall ignore (i.e., remove a profile specified in Annex A of [EVC] shall ignore (i.e.,
from the bitstream and discard) all NAL units with values of remove from the bitstream and discard) all NAL units with
nuh_extension_flag equal to 1. values of nuh_extension_flag equal to 1.
1.2. Overview of the Payload Format 1.2. Overview of the Payload Format
This payload format defines the following processes required for This payload format defines the following processes required for
transport of EVC-coded data over RTP [RFC3550]: transport of EVC-coded data over RTP [RFC3550]:
* usage of RTP header with this payload format * usage of RTP header with this payload format
* packetization of EVC-coded NAL units into RTP packets using three * packetization of EVC-coded NAL units into RTP packets using three
types of payload structures: a single NAL unit, aggregation, and types of payload structures: a single NAL unit, aggregation, and
fragment unit fragment unit
* transmission of EVC NAL units of the same bitstream within a * transmission of EVC NAL units of the same bitstream within a
single RTP stream. single RTP stream
* media type parameters to be used with the Session Description * usage of media type parameters to be used with the Session
Protocol (SDP) [RFC8866] Description Protocol (SDP) [RFC8866]
* usage of RTCP feedback messages * usage of RTCP feedback messages
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown above. capitals, as shown here.
3. Definitions and Abbreviations 3. Definitions and Abbreviations
3.1. Definitions 3.1. Definitions
This document uses the terms and definitions of EVC. Section 3.1.1 This document uses the terms and definitions of EVC. Section 3.1.1
lists relevant definitions from [EVC] for convenience. Section 3.1.2 lists relevant definitions from [EVC] for convenience. Section 3.1.2
provides definitions specific to this document. provides definitions specific to this document.
3.1.1. Definitions from the EVC Standard 3.1.1. Definitions from the EVC Standard
Access Unit: A set of NAL units that are associated with each other Access Unit (AU):
according to a specified classification rule, are consecutive in A set of NAL units that are associated with each other according
decoding order, and contain exactly one coded picture. to a specified classification rule, are consecutive in decoding
order, and contain exactly one coded picture.
Adaptation parameter set (APS): A syntax structure containing syntax Adaptation Parameter Set (APS):
elements that apply to zero or more slices as determined by zero or A syntax structure containing syntax elements that apply to zero
more syntax elements found in slice headers. or more slices as determined by zero or more syntax elements found
in slice headers.
Bitstream: A sequence of bits, in the form of a NAL unit stream or a Bitstream:
byte stream, that forms the representation of coded pictures and A sequence of bits, in the form of a NAL unit stream or a byte
associated data forming one or more coded video sequences (CVSs). stream, that forms the representation of coded pictures and
associated data forming one or more CVSs.
Coded Picture: A coded representation of a picture containing all Coded Picture:
CTUs of the picture. A coded representation of a picture containing all CTUs of the
picture.
Coded Video Sequence (CVS): A sequence of access units that consists, Coded Video Sequence (CVS):
in decoding order, of an IDR access unit, followed by zero or more A sequence of access units that consists, in decoding order, of an
access units that are not IDR access units, including all subsequent IDR access unit, followed by zero or more access units that are
access units up to but not including any subsequent access unit that not IDR access units, including all subsequent access units up to
is an IDR access unit. but not including any subsequent access unit that is an IDR access
unit.
Coding Tree Block (CTB): An NxN block of samples for some value of N Coding Tree Block (CTB):
such that the division of a component into CTBs is a partitioning. An NxN block of samples for some value of N such that the division
of a component into CTBs is a partitioning.
Coding Tree Unit (CTU): A CTB of luma samples, two corresponding CTBs Coding Tree Unit (CTU):
of chroma samples of a picture that has three sample arrays, or a CTB A CTB of luma samples, two corresponding CTBs of chroma samples of
of samples of a monochrome picture or a picture that is coded using a picture that has three sample arrays, or a CTB of samples of a
three separate colour planes and syntax structures used to code the monochrome picture or a picture that is coded using three separate
samples. color planes and syntax structures used to code the samples.
Decoded Picture: A decoded picture is derived by decoding a coded Decoded Picture:
picture. A decoded picture is derived by decoding a coded picture.
Decoded Picture Buffer (DPB): A buffer holding decoded pictures for Decoded Picture Buffer (DPB):
reference, output reordering, or output delay specified for the A buffer holding decoded pictures for reference, output
hypothetical reference decoder in Annex C of [EVC] standard. reordering, or output delay specified for the hypothetical
reference decoder in Annex C of the [EVC] standard.
Dynamic Range Adjustment (DRA): A mapping process that is applied to Dynamic Range Adjustment (DRA):
decoded picture prior to cropping and output as part of the decoding A mapping process that is applied to the decoded picture prior to
process and is controlled by parameters conveyed in an Adaptation cropping and output as part of the decoding process; it is
Parameter Set (APS). controlled by parameters conveyed in an Adaptation Parameter Set
(APS).
Hypothetical Reference Decoder (HRD): A hypothetical decoder model Hypothetical Reference Decoder (HRD):
that specifies constraints on the variability of conforming NAL unit A hypothetical decoder model that specifies constraints on the
streams or conforming byte streams that an encoding process may variability of conforming NAL unit streams or conforming byte
produce. streams that an encoding process may produce.
IDR access unit: access unit in which the coded picture is an IDR IDR Access Unit:
picture. An access unit in which the coded picture is an IDR picture.
IDR picture: coded picture for which each VCL NAL unit has IDR Picture:
NalUnitType equal to IDR_NUT. The coded picture for which each VCL NAL unit has NalUnitType
equal to IDR_NUT.
Level: A defined set of constraints on the values that may be taken Level:
by the syntax elements and variables of this document, or the value A defined set of constraints on the values that may be taken by
of a transform coefficient prior to scaling. the syntax elements and variables of this document, or the value
of a transform coefficient prior to scaling.
Network Abstraction Layer (NAL) unit: A syntax structure containing Network Abstraction Layer (NAL) Unit:
an indication of the type of data to follow and bytes containing that A syntax structure containing an indication of the type of data to
data in the form of an RBSP interspersed as necessary. follow and bytes containing that data in the form of an RBSP
interspersed as necessary.
Network Abstraction Layer (NAL) Unit Stream: A sequence of NAL units. Network Abstraction Layer (NAL) Unit Stream:
A sequence of NAL units.
Non-IDR Picture: A coded picture that is not an IDR picture. Non-IDR Picture:
A coded picture that is not an IDR picture.
Non-VCL NAL Unit: A NAL unit that is not a VCL NAL unit. Non-VCL NAL Unit:
A NAL unit that is not a VCL NAL unit.
Picture Parameter Set (PPS): A syntax structure containing syntax Picture Parameter Set (PPS):
elements that apply to zero or more entire coded pictures as A syntax structure containing syntax elements that apply to zero
determined by a syntax element found in each slice header. or more entire coded pictures as determined by a syntax element
found in each slice header.
Picture Order Count (POC): A variable that is associated with each Picture Order Count (POC):
picture, uniquely identifies the associated picture among all A variable that is associated with each picture, uniquely
pictures in the CVS, and, when the associated picture is to be output identifies the associated picture among all pictures in the CVS,
from the decoded picture buffer, indicates the position of the and (when the associated picture is to be output from the DPB)
associated picture in output order relative to the output order indicates the position of the associated picture in output order
positions of the other pictures in the same CVS that are to be output relative to the output order positions of the other pictures in
from the decoded picture buffer. the same CVS that are to be output from the DPB.
Raw Byte Sequence Payload (RBSP): A syntax structure containing an Raw Byte Sequence Payload (RBSP):
integer number of bytes that is encapsulated in a NAL unit and that A syntax structure containing an integer number of bytes that is
is either empty or has the form of a string of data bits containing encapsulated in a NAL unit and that is either empty or has the
syntax elements followed by an RBSP stop bit and zero or more form of a string of data bits containing syntax elements followed
subsequent bits equal to 0. by an RBSP stop bit and zero or more subsequent bits equal to 0.
Sequence Parameter Set (SPS): A syntax structure containing syntax Sequence Parameter Set (SPS):
elements that apply to zero or more entire CVSs as determined by the A syntax structure containing syntax elements that apply to zero
content of a syntax element found in the PPS referred to by a syntax or more entire CVSs as determined by the content of a syntax
element found in each slice header. element found in the PPS referred to by a syntax element found in
each slice header.
Slice: integer number of tiles of a picture in the tile scan of the Slice:
picture and that are exclusively contained in a single NAL unit. An integer number of tiles of a picture in the tile scan of the
picture, exclusively contained in a single NAL unit.
Tile: rectangular region of CTUs within a particular tile column and Tile:
a particular tile row in a picture. A rectangular region of CTUs within a particular tile column and a
particular tile row in a picture.
Tile column: rectangular region of CTUs having a height equal to the Tile Column:
height of the picture and width specified by syntax elements in the A rectangular region of CTUs having a height equal to the height
PPS. of the picture and width specified by syntax elements in the PPS.
Tile row: A rectangular region of CTUs having a height specified by Tile Row:
syntax elements in the PPS and a width equal to the width of the A rectangular region of CTUs having a height specified by syntax
picture. elements in the PPS and a width equal to the width of the picture.
Tile scan: A specific sequential ordering of CTUs partitioning a Tile Scan:
picture in which the CTUs are ordered consecutively in CTU raster A specific sequential ordering of CTUs partitioning a picture in
scan in a tile whereas tiles in a picture are ordered consecutively which the CTUs are ordered consecutively in CTU raster scan in a
in a raster scan of the tiles of the picture. tile, whereas tiles in a picture are ordered consecutively in a
raster scan of the tiles of the picture.
Video coding layer (VCL) NAL unit: A collective term for coded slice Video Coding Layer (VCL) NAL Unit:
NAL units and the subset of NAL units that have reserved values of A collective term for coded slice NAL units and the subset of NAL
NalUnitType that are classified as VCL NAL units in this document. units that have reserved values of NalUnitType that are classified
as VCL NAL units in this document.
3.1.2. Definitions Specific to This Document 3.1.2. Definitions Specific to This Document
Media-Aware Network Element (MANE): A network element, such as a Media-Aware Network Element (MANE):
middlebox, selective forwarding unit, or application-layer gateway A network element, such as a middlebox, selective forwarding unit,
that is capable of parsing certain aspects of the RTP payload headers or application-layer gateway, that is capable of parsing certain
or the RTP payload and reacting to their contents. aspects of the RTP payload headers or the RTP payload and reacting
to their contents.
Informative note: The concept of a MANE goes beyond normal routers | Informative note: The concept of a MANE goes beyond normal
or gateways in that a MANE has to be aware of the signaling (e.g., | routers or gateways in that a MANE has to be aware of the
to learn about the payload type mappings of the media streams), | signaling (e.g., to learn about the payload type mappings of
and in that it has to be trusted when working with Secure RTP | the media streams), and in that it has to be trusted when
(SRTP). The advantage of using MANEs is that they allow packets | working with Secure RTP (SRTP). The advantage of using
to be dropped according to the needs of the media coding. For | MANEs is that they allow packets to be dropped according to
example, if a MANE has to drop packets due to congestion on a | the needs of the media coding. For example, if a MANE has
certain link, it can identify and remove those packets whose | to drop packets due to congestion on a certain link, it can
elimination produces the least adverse effect on the user | identify and remove those packets whose elimination produces
experience. After dropping packets, MANEs must rewrite RTCP | the least adverse effect on the user experience. After
packets to match the changes to the RTP stream, as specified in | dropping packets, MANEs must rewrite RTCP packets to match
Section 7 of [RFC3550]. | the changes to the RTP stream, as specified in Section 7 of
| [RFC3550].
NAL unit decoding order: A NAL unit order that conforms to the NAL unit decoding order:
constraints on NAL unit order given in Section 7.4.2.3 in [EVC], A NAL unit order that conforms to the constraints on NAL unit
follow the order of NAL units in the bitstream. order given in Section 7.4.2.3 of [EVC] and follows the order of
NAL units in the bitstream.
NALU-time: The value that the RTP timestamp would have if the NAL NALU-time:
unit would be transported in its own RTP packet. The value that the RTP timestamp would have if the NAL unit would
be transported in its own RTP packet.
NAL unit output order: A NAL unit order in which NAL units of NAL unit output order:
different access units are in the output order of the decoded A NAL unit order in which NAL units of different access units are
pictures corresponding to the access units, as specified in [EVC], in the output order of the decoded pictures corresponding to the
and in which NAL units within an access unit are in their decoding access units, as specified in [EVC], and in which NAL units within
order. an access unit are in their decoding order.
RTP stream: See [RFC7656]. Within the scope of this document, one RTP stream:
RTP stream is utilized to transport a EVC bitstream, which may See [RFC7656]. Within the scope of this document, one RTP stream
contain one or more temporal sub-layers. is utilized to transport an EVC bitstream, which may contain one
or more temporal sub-layers.
Transmission order: The order of packets in ascending RTP sequence Transmission order:
number order (in modulo arithmetic). Within an aggregation packet, The order of packets in ascending RTP sequence number order (in
the NAL unit transmission order is the same as the order of modulo arithmetic). Within an Aggregation Packet (AP), the NAL
appearance of NAL units in the packet. unit transmission order is the same as the order of appearance of
NAL units in the packet.
3.2. Abbreviations 3.2. Abbreviations
AU Access Unit AU Access Unit
AP Aggregation Packet AP Aggregation Packet
APS Adaptation Parameter Set APS Adaptation Parameter Set
ATS Adaptive Transform Selection ATS Adaptive Transform Selection
B Bi-predictive B Bi-predictive
CBR Constant Bit Rate CBR Constant Bit Rate
CPB Coded Picture Buffer
CTB Coding Tree Block CPB Coded Picture Buffer
CTU Coding Tree Unit CTB Coding Tree Block
CVS Coded Video Sequence CTU Coding Tree Unit
DPB Decoded Picture Buffer CVS Coded Video Sequence
HRD Hypothetical Reference Decoder DPB Decoded Picture Buffer
HSS Hypothetical Stream Scheduler HRD Hypothetical Reference Decoder
I Intra HSS Hypothetical Stream Scheduler
IDR Instantaneous Decoding Refresh I Intra
LSB Least Significant Bit IDR Instantaneous Decoding Refresh
LTRP Long-Term Reference Picture LSB Least Significant Bit
MMVD Merge with Motion Vector Difference LTRP Long-Term Reference Picture
MSB Most Significant Bit MMVD Merge with Motion Vector Difference
NAL Network Abstraction Layer MSB Most Significant Bit
P Predictive NAL Network Abstraction Layer
POC Picture Order Count P Predictive
PPS Picture Parameter Set POC Picture Order Count
QP Quantization Parameter PPS Picture Parameter Set
RBSP Raw Byte Sequence Payload QP Quantization Parameter
RGB Same as GBR RBSP Raw Byte Sequence Payload
SAR Sample Aspect Ratio RGB Same as GBR
SEI Supplemental Enhancement Information SAR Sample Aspect Ratio
SODB String Of Data Bits SEI Supplemental Enhancement Information
SPS Sequence Parameter Set SODB String Of Data Bits
STRP Short-Term Reference Picture
VBR Variable Bit Rate SPS Sequence Parameter Set
VCL Video Coding Layer STRP Short-Term Reference Picture
VBR Variable Bit Rate
VCL Video Coding Layer
4. RTP Payload Format 4. RTP Payload Format
4.1. RTP Header Usage 4.1. RTP Header Usage
The format of the RTP header is specified in [RFC3550] (reprinted as The format of the RTP header is specified in [RFC3550] (included as
Figure 2 for convenience). This payload format uses the fields of Figure 2 for convenience). This payload format uses the fields of
the header in a manner consistent with that specification. the header in a manner consistent with that specification.
The RTP payload (and the settings for some RTP header bits) for The RTP payload (and the settings for some RTP header bits) for APs
aggregation packets and fragmentation units are specified in and Fragmentation Units (FUs) are specified in Sections 4.3.2 and
Section 4.3.2 and Section 4.3.3, respectively. 4.3.3, respectively.
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 |
| .... | | .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RTP Header According to [RFC3550] Figure 2: RTP Header According to RFC 3550
Figure 2
The RTP header information to be set according to this RTP payload The RTP header information to be set according to this RTP payload
format is set as follows: format is set as follows:
Marker bit (M): 1 bit Marker bit (M): 1 bit
Set for the last packet of the access unit, carried in the current Set for the last packet of the access unit and carried in the
RTP stream. This is in line with the normal use of the M bit in current RTP stream. This is in line with the normal use of the M
video formats to allow an efficient playout buffer handling. bit in video formats to allow an efficient playout buffer
handling.
Payload Type (PT): 7 bits
Payload Type (PT): 7 bits
The assignment of an RTP payload type for this new payload format The assignment of an RTP payload type for this new payload 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. through the profile used or in a dynamic way.
Sequence Number (SN): 16 bits Sequence Number (SN): 16 bits
Set and used in accordance with [RFC3550]. Set and used in accordance with [RFC3550].
Timestamp: 32 bits Timestamp: 32 bits
The RTP timestamp is set to the sampling timestamp of the content. The RTP timestamp is set to the sampling timestamp of the content.
A 90 kHz clock rate MUST be used. If the NAL unit has no timing A 90 kHz clock rate MUST be used. If the NAL unit has no timing
properties of its own (e.g., parameter sets or certain SEI NAL properties of its own (e.g., parameter sets or certain SEI NAL
units), the RTP timestamp MUST be set to the RTP timestamp of the units), the RTP timestamp MUST be set to the RTP timestamp of the
coded picture of the access unit in which the NAL unit is coded picture of the access unit in which the NAL unit is
included. For SEI messages, this information is specified in included. For SEI messages, this information is specified in
Annex D of [EVC]. Receivers MUST use the RTP timestamp for the Annex D of [EVC]. Receivers MUST use the RTP timestamp for the
display process, even when the bitstream contains picture timing display process, even when the bitstream contains picture timing
SEI messages or decoding unit information SEI messages as SEI messages or decoding unit information SEI messages as
specified in [EVC]. specified in [EVC].
Synchronization source (SSRC): 32 bits Synchronization source (SSRC): 32 bits
Used to identify the source of the RTP packets. According to this Used to identify the source of the RTP packets. According to this
document, a single SSRC is used for all parts of a single document, a single SSRC is used for all parts of a single
bitstream. bitstream.
4.2. Payload Header Usage 4.2. Payload Header Usage
The first two bytes of the payload of an RTP packet are referred to 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, TID, Reserve and E) as the NAL unit header as shown in fields (F, TID, Reserve, and E) as the NAL unit header, as shown in
Section 1.1.4, irrespective of the type of the payload structure. Section 1.1.4, irrespective of the type of the payload structure.
The TID value indicates (among other things) the relative importance The TID value indicates (among other things) the relative importance
of an RTP packet, for example, because NAL units with larger TID of an RTP packet, for example, because NAL units with larger TID
value are not used for the decoding of the ones with smaller TID values are not used to decode the ones with smaller TID values. A
value. A lower value of TID indicates a higher importance. More- lower value of TID indicates a higher importance. More important NAL
important NAL units MAY be better protected against transmission units MAY be better protected against transmission losses than less
losses than less-important NAL units. important NAL units.
4.3. Payload Structures 4.3. Payload Structures
Three different types of RTP packet payload structures are specified. 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. Type field in the payload header.
The three different payload structures are as follows: The three different payload structures are as follows:
* Single NAL unit packet: Contains a single NAL unit in the payload, * Single NAL unit packet: Contains a single NAL unit in the payload,
skipping to change at page 18, line 20 skipping to change at line 836
* Aggregation Packet (AP): Contains more than one NAL unit within * Aggregation Packet (AP): Contains more than one NAL unit within
one access unit. This payload structure is specified in one access unit. This payload structure is specified in
Section 4.3.2. Section 4.3.2.
* Fragmentation Unit (FU): Contains a subset of a single NAL unit. * Fragmentation Unit (FU): Contains a subset of a single NAL unit.
This payload structure is specified in Section 4.3.3. This payload structure is specified in Section 4.3.3.
4.3.1. Single NAL Unit Packets 4.3.1. Single NAL Unit Packets
A single NAL unit packet contains exactly one NAL unit, and consists A single NAL unit packet contains exactly one NAL unit and consists
of a payload header as defined in Table 4 of [EVC] (denoted as of a payload header as defined in Table 4 of [EVC] (denoted as
PayloadHdr), followed by a conditional 16-bit DONL field (in network PayloadHdr), followed by a conditional 16-bit DONL field (in network
byte order), and the NAL unit payload data (the NAL unit excluding byte order), and the NAL unit payload data (the NAL unit excluding
its NAL unit header) of the contained NAL unit, as shown in Figure 3. its NAL unit header) of the contained NAL unit, as shown in Figure 3.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Structure of a Single NAL Unit Packet Figure 3: The Structure of a Single NAL Unit Packet
Figure 3
The DONL field, when present, specifies the value of the 16 least The DONL field, when present, specifies the value of the 16 least
significant bits of the decoding order number of the contained NAL significant bits of the decoding order number of the contained NAL
unit. If sprop-max-don-diff (defined in Section 7.2 is greater than unit. If sprop-max-don-diff (defined in Section 7.2) is greater than
0, the DONL field MUST be present, and the variable DON for the 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 field. Otherwise (where sprop-max-don-diff is equal to 0), the DONL
MUST NOT be present. field MUST NOT be present.
4.3.2. Aggregation Packets (APs) 4.3.2. Aggregation Packets (APs)
Aggregation Packets (APs) enable the reduction of packetization Aggregation Packets (APs) enable the reduction of packetization
overhead for small NAL units, such as most of the non-VCL NAL units, overhead for small NAL units, such as most of the non-VCL NAL units,
which are often only a few octets in size. which are often only a few octets in size.
An AP aggregates NAL units of one access unit, and it MUST NOT An AP aggregates NAL units of one access unit, and it MUST NOT
contain NAL units from more than one AU. Each NAL unit to be carried contain NAL units from more than one AU. Each NAL unit to be carried
in an AP is encapsulated in an aggregation unit. NAL units in an AP is encapsulated in an aggregation unit. NAL units
aggregated in one AP are included in NAL-unit-decoding order. aggregated in one AP are included in NAL-unit-decoding order.
An AP consists of a payload header, as defined in Table 4 of [EVC] An AP consists of a payload header, as defined in Table 4 of [EVC]
(denoted here as PayloadHdr with Type=56) followed by two or more (denoted here as PayloadHdr with Type=56), followed by two or more
aggregation units, as shown in Figure 4. aggregation units, as shown in Figure 4.
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=56) | | | PayloadHdr (Type=56) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| two or more aggregation units | | two or more aggregation units |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Structure of an Aggregation Packet Figure 4: The Structure of an Aggregation Packet
Figure 4
The fields in the payload header of an AP are set as follows. The F 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 bit MUST 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 equal to zero; otherwise, it MUST be equal to 1. The Type field MUST
be equal to 56. be equal to 56.
The value of TID MUST be the smallest value of TID of all the The value of TID MUST be the smallest value of TID of all the
aggregated NAL units. The value of Reserve and E MUST be equal to 0 aggregated NAL units. The value of Reserve and E MUST be equal to 0
for this specification. for this specification.
Informative note: All VCL NAL units in an AP have the same TID | 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
may contain non-VCL NAL units for which the TID value in the NAL | AP may contain non-VCL NAL units for which the TID value in the
unit header may be different from the TID value of the VCL NAL | NAL unit header may be different from the TID value of the VCL
units in the same AP. | NAL units in the same AP.
An AP MUST carry at least two aggregation units and can carry as many 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 MUST fit into an IP packet, and the size SHOULD be
chosen so that the resulting IP packet is smaller than the path MTU chosen so that the resulting IP packet is smaller than the path MTU
size so to avoid IP layer fragmentation. An AP MUST NOT contain FUs size so to avoid IP layer fragmentation. An AP MUST NOT contain FUs
specified in Section 4.3.3. APs MUST NOT be nested; i.e., an AP can specified in Section 4.3.3. APs MUST NOT be nested; i.e., an AP
not contain another AP. cannot contain another AP.
Informative note: If a receiver encounters nested Aggregation | Informative note: If a receiver encounters nested APs, which is
Packets, which is against the aforementioned requirement, it has | against the aforementioned requirement, it has several options,
several options, listed in order of ease of implementation: 1) | listed in order of ease of implementation: 1) ignore the nested
Ignore the nested AP; 2) Ignore the nested AP and report a "packet | AP; 2) ignore the nested AP and report a "packet loss" to the
loss" to the decoder, if such functionality exists in the API, 3) | decoder, if such functionality exists in the API; and 3)
Implement support for nested APs and extract the Network | implement support for nested APs and extract the NAL units from
Abstraction Layer (NAL) units from these nested APs. | these nested APs.
The first aggregation unit in an AP consists of a conditional 16-bit The first aggregation unit in an AP consists of a conditional 16-bit
DONL field (in network byte order) followed by a 16-bit unsigned size DONL field (in network byte order) followed by a 16-bit unsigned size
information (in network byte order) that indicates the size of the information (in network byte order) that indicates the size of the
NAL unit in bytes (excluding these two octets but including the NAL 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 Figure 5. header, as shown in Figure 5.
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 |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : | :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Structure of the First Aggregation Unit in an AP Figure 5: The Structure of the First Aggregation Unit in an AP
Figure 5
Informative note: The first octet of Figure 5 (indicated by the | Informative note: The first octet of Figure 5 (indicated by the
first colon) belongs to a previous aggregation unit. It is | first colon) belongs to a previous aggregation unit. It is
depicted to emphasize that aggregation units are octet aligned | depicted to emphasize that aggregation units are octet aligned
only. Similarly, the NAL unit carried in the aggregation unit can | only. Similarly, the NAL unit carried in the aggregation unit
terminate at the octet boundary. | can terminate at the octet boundary.
The DONL field, when present, specifies the value of the 16 least The DONL field, when present, specifies the value of the 16 least
significant bits of the decoding order number of the aggregated NAL significant bits of the decoding order number of the aggregated NAL
unit. unit.
If sprop-max-don-diff is greater than 0, the DONL field MUST be If sprop-max-don-diff is greater than 0, the DONL field MUST be
present in an aggregation unit that is the first aggregation unit in present in an aggregation unit that is the first aggregation unit in
an AP. The variable DON for the aggregated NAL unit is derived as an AP. The variable DON for the aggregated NAL unit is derived as
equal to the value of the DONL field, and the variable DON for an equal to the value of the DONL field, and the variable DON for an
aggregation unit that is not the first aggregation unit in an AP- aggregation unit that is not the first aggregation unit in an AP-
aggregated NAL unit is derived as equal to the DON of the preceding aggregated NAL unit is derived as equal to the DON of the preceding
aggregated NAL unit in the same AP plus 1 modulo 65536. Otherwise aggregated NAL unit in the same AP plus 1 modulo 65536. Otherwise
(sprop-max-don-diff is equal to 0), the DONL field MUST NOT be (where sprop-max-don-diff is equal to 0), the DONL field MUST NOT be
present in an aggregation unit that is the first aggregation unit in present in an aggregation unit that is the first aggregation unit in
an AP an AP.
An aggregation unit that is not the first aggregation unit in an AP An aggregation unit that is not the first aggregation unit in an AP
will be followed immediately by a 16-bit unsigned size information will be followed immediately by a 16-bit unsigned size information
(in network byte order) that indicates the size of the NAL unit in (in network byte order) that indicates the size of the NAL unit in
bytes (excluding these two octets but including the NAL unit header), bytes (excluding these two octets but including the NAL unit header),
followed by the NAL unit itself, including its NAL unit header, as followed by the NAL unit itself, including its NAL unit header, as
shown in Figure 6. shown in Figure 6.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : | :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Structure of an Aggregation Unit That Is Not the First Figure 6: The Structure of an Aggregation Unit That Is Not the First
Aggregation Unit in an AP Aggregation Unit in an AP
Figure 6
Informative note: The first octet of Figure 6 (indicated by the | Informative note: The first octet of Figure 6 (indicated by the
first colon) belongs to a previous aggregation unit. It is | first colon) belongs to a previous aggregation unit. It is
depicted to emphasize that aggregation units are octet aligned | depicted to emphasize that aggregation units are octet aligned
only. Similarly, the NAL unit carried in the aggregation unit can | only. Similarly, the NAL unit carried in the aggregation unit
terminate at the octet boundary. | can terminate at the octet boundary.
Figure 7 presents an example of an AP that contains two aggregation Figure 7 presents an example of an AP that contains two aggregation
units, labeled as NALU 1 and NALU 2 in the figure, without the DONL units, labeled "NALU 1" and "NALU 2", without the DONL field being
field being present. present.
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=56) | NALU 1 Size | | PayloadHdr (Type=56) | NALU 1 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 1 HDR | | | NALU 1 HDR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 1 Data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 1 Data |
skipping to change at page 22, line 26 skipping to change at line 1017
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . | 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An Example of an AP Packet Containing Figure 7: An Example of an AP Packet Containing Two Aggregation
Two Aggregation Units without the DONL Field Units without the DONL Field
Figure 7
Figure 8 presents an example of an AP that contains two aggregation Figure 8 presents an example of an AP that contains two aggregation
units, labeled as NALU 1 and NALU 2 in the figure, with the DONL units, labeled "NALU 1" and "NALU 2", with the DONL field being
field being present. present.
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=56) | NALU 1 DONL | | PayloadHdr (Type=56) | NALU 1 DONL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 1 Size | NALU 1 HDR | | NALU 1 Size | NALU 1 HDR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 23, line 27 skipping to change at line 1046
+ . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : NALU 2 Size | | : NALU 2 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NALU 2 HDR | | | NALU 2 HDR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 2 Data | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NALU 2 Data |
| | | |
| . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An Example of an AP Containing Figure 8: An Example of an AP Containing Two Aggregation Units
Two Aggregation Units with the DONL Field with the DONL Field
Figure 8
4.3.3. Fragmentation Units 4.3.3. Fragmentation Units (FUs)
Fragmentation Units (FUs) are introduced to enable fragmenting a FUs are introduced to enable fragmenting a single NAL unit into
single NAL unit into multiple RTP packets, possibly without multiple RTP packets, possibly without cooperation or knowledge of
cooperation or knowledge of the EVC encoder. A fragment of a NAL the EVC encoder. A fragment of a NAL unit consists of an integer
unit consists of an integer number of consecutive octets of that NAL number of consecutive octets of that NAL unit. Fragments of the same
unit. Fragments of the same NAL unit MUST be sent in consecutive NAL unit MUST be sent in consecutive order with ascending RTP
order with ascending RTP sequence numbers (with no other RTP packets sequence numbers (with no other RTP packets within the same RTP
within the same RTP stream being sent between the first and last stream being sent between the first and last fragment).
fragment).
When a NAL unit is fragmented and conveyed within FUs, it is referred When a NAL unit is fragmented and conveyed within FUs, it is referred
to as a fragmented NAL unit. APs MUST NOT be fragmented. FUs MUST to as a fragmented NAL unit. APs MUST NOT be fragmented. FUs MUST
NOT be nested; i.e., an FU must not contain a subset of another FU. NOT be nested; i.e., an FU must not contain a subset of another FU.
The RTP timestamp of an RTP packet carrying an FU is set to the NALU- The RTP timestamp of an RTP packet carrying an FU is set to the NALU-
time of the fragmented NAL unit. time of the fragmented NAL unit.
An FU consists of a payload header as defined in Table 4 of [EVC] An FU consists of a payload header as defined in Table 4 of [EVC]
(denoted as PayloadHdr with type=57), an FU header of one octet, a (denoted as PayloadHdr with Type=57), an FU header of one octet, a
conditional 16-bit DONL field (in network byte order), and an FU conditional 16-bit DONL field (in network byte order), and an FU
payload, as shown in Figure 9. payload, as shown in Figure 9.
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=57) | FU header | DONL (cond) | | PayloadHdr (Type=57) | FU header | DONL (cond) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| DONL (cond) | | | DONL (cond) | |
|-+-+-+-+-+-+-+-+ | |-+-+-+-+-+-+-+-+ |
| FU payload | | FU payload |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| :...OPTIONAL RTP padding | | :...OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Structure of an FU Figure 9: The Structure of an FU
Figure 9
The fields in the payload header are set as follows. The Type field The fields in the payload header are set as follows. The Type field
MUST be equal to 57. The fields F, TID, Reserve and E MUST be equal MUST be equal to 57. The fields F, TID, Reserve, and E MUST be equal
to the fields F, TID, Reserve and E, respectively, of the fragmented to the fields F, TID, Reserve, and E, respectively, of the fragmented
NAL unit. NAL unit.
The FU header consists of an S bit, an E bit, and a 6-bit FuType The FU header consists of an S bit, an E bit, and a 6-bit FuType
field, as shown in Figure 10. field, as shown in Figure 10.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|S|E| FuType | |S|E| FuType |
+---------------+ +---------------+
The Structure of FU Header Figure 10: The Structure of FU Header
Figure 10
The semantics of the FU header fields are as follows: The semantics of the FU header fields are as follows:
S: 1 bit S: 1 bit
When set to 1, the S bit indicates the start of a fragmented NAL 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. bit MUST be set to 0.
E: 1 bit E: 1 bit
When set to 1, the E bit indicates the end of a fragmented NAL 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. fragment of a fragmented NAL unit, the E bit MUST be set to 0.
FuType: 6 bits FuType: 6 bits
The field FuType MUST be equal to the field Type of the fragmented The field FuType MUST be equal to the field Type of the fragmented
NAL unit. NAL unit.
The DONL field, when present, specifies the value of the 16 least The DONL field, when present, specifies the value of the 16 least
significant bits of the decoding order number of the fragmented NAL significant bits of the decoding order number of the fragmented NAL
unit. unit.
If sprop-max-don-diff is greater than 0, and the S bit is equal to 1, If sprop-max-don-diff is greater than 0 and the S bit is equal to 1,
the DONL field MUST be present in the FU, and the variable DON for the DONL field MUST be present in the FU, and the variable DON for
the fragmented NAL unit is derived as equal to the value of the DONL the fragmented NAL unit is derived as equal to the value of the DONL
field. Otherwise (sprop-max-don-diff is equal to 0, or the S bit is field. Otherwise (where sprop-max-don-diff is equal to 0, or where
equal to 0), the DONL field MUST NOT be present in the FU. the S bit is equal to 0), the DONL field MUST NOT be present in the
FU.
A non-fragmented NAL unit MUST NOT be transmitted in one FU; i.e., A non-fragmented NAL unit MUST NOT be transmitted in 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. header.
The FU payload consists of fragments of the payload of the fragmented The FU payload consists of fragments of the payload of the fragmented
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.
rather the information of the NAL unit header of the fragmented NAL Instead, the information of the NAL unit header of the fragmented NAL
unit is conveyed in F, TID, Reserve and E fields of the FU payload unit is conveyed in F, TID, Reserve, and E 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. An FU payload MUST NOT be empty.
If an FU is lost, the receiver SHOULD discard all following If an FU is lost, the receiver SHOULD discard all following
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
gracefully handle incomplete NAL units. gracefully handle incomplete NAL units.
A receiver in an endpoint or a MANE MAY aggregate the first n-1 A receiver in an endpoint or a MANE MAY aggregate 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 MUST be set to 1 to indicate a
syntax violation. syntax violation.
4.4. Decoding Order Number 4.4. Decoding Order Number
For each NAL unit, the variable AbsDon is derived, representing the For each NAL unit, the variable AbsDon is derived; it represents the
decoding order number that is indicative of the NAL unit decoding decoding order number that is indicative of the NAL unit decoding
order. order.
Let NAL unit n be the n-th NAL unit in transmission order within an Let NAL unit n be the n-th NAL unit in transmission order within an
RTP stream. RTP stream.
If sprop-max-don-diff is equal to 0, AbsDon[n], the value of AbsDon If sprop-max-don-diff is equal to 0, then AbsDon[n] (the value of
for NAL unit n, is derived as equal to n. AbsDon for NAL unit n) is derived as equal to n.
Otherwise (sprop-max-don-diff is greater than 0), AbsDon[n] is Otherwise (where sprop-max-don-diff is greater than 0), AbsDon[n] is
derived as follows, where DON[n] is the value of the variable DON for derived as follows, where DON[n] is the value of the variable DON for
NAL unit n: NAL unit n:
* If n is equal to 0 (i.e., NAL unit n is the very first NAL unit in * 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]. transmission order), AbsDon[0] is set equal to DON[0].
* Otherwise (n is greater than 0), the following applies for * Otherwise (where n is greater than 0), the following applies for
derivation of AbsDon[n]: derivation of AbsDon[n]:
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])
For any two NAL units m and n, the following applies: For any two NAL units (m and n), the following applies:
* AbsDon[n] greater than AbsDon[m] indicates that NAL unit n follows * When AbsDon[n] is greater than AbsDon[m], the NAL unit n follows
NAL unit m in NAL unit decoding order. NAL unit m in NAL unit decoding order.
* When AbsDon[n] is equal to AbsDon[m], the NAL unit decoding order * When AbsDon[n] is equal to AbsDon[m], the NAL unit decoding order
of the two NAL units can be in either order. of the two NAL units can be in either order.
* AbsDon[n] less than AbsDon[m] indicates that NAL unit n precedes * When AbsDon[n] is less than AbsDon[m], the NAL unit n precedes NAL
NAL unit m in decoding order. unit m in decoding order.
Informative note: When two consecutive NAL units in the NAL | Informative note: When two consecutive NAL units in the NAL
unit decoding order has different values of AbsDon, the the | unit decoding order has 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. | greater than or equal to 1.
Informative note: There are multiple reasons to allow for | Informative note: There are multiple reasons to allow the
the absolute difference of the values of AbsDon for two | absolute difference of the values of AbsDon for two consecutive
consecutive NAL units in the NAL unit decoding order to be | NAL units in the NAL unit decoding order to be greater than
greater than one. An increment by one is not required, as | one. An increment by one is not required as at the time of
at the time of associating values of AbsDon to NAL units, it | associating values of AbsDon to NAL units, it may not be known
may not be known whether all NAL units are to be delivered | whether all NAL units are to be delivered to the receiver. For
to the receiver. For example, a gateway might not forward | example, a gateway might not forward VCL NAL units of higher
VCL NAL units of higher sub-layers or some SEI NAL units | sub-layers or some SEI NAL units when there is congestion in
when there is congestion in the network. In another | the network. In another example, the first intra-coded picture
example, the first intra-coded picture of a pre-encoded clip | of a pre-encoded clip is transmitted in advance to ensure that
is transmitted in advance to ensure that it is readily | it is readily available in the receiver. When transmitting the
available in the receiver. When transmitting the first | first intra-coded picture, the originator still determines how
intra-coded picture, the originator still determines how | many NAL units will be encoded before the first intra-coded
many NAL units will be encoded before the first intra-coded | picture of the pre-encoded clip follows in decoding order.
picture of the pre-encoded clip follows in decoding order. | Thus, the values of AbsDon for the NAL units of the first
Thus, the values of AbsDon for the NAL units of the first | intra-coded picture of the pre-encoded clip have to be
intra-coded picture of the pre-encoded clip have to be | estimated when they are transmitted and gaps in the values of
estimated when they are transmitted, and gaps in the values | AbsDon may occur.
of AbsDon may occur.
5. Packetization Rules 5. Packetization Rules
The following packetization rules apply: The following packetization rules apply:
* If sprop-max-don-diff is greater than 0, the transmission order of * If sprop-max-don-diff is greater than 0, the transmission order of
NAL units carried in the RTP stream MAY be different from the NAL NAL units carried in the RTP stream MAY be different from the NAL
unit decoding order. Otherwise (sprop-max-don-diff equals 0), the unit decoding order. Otherwise (where sprop-max-don-diff equals
transmission order of NAL units carried in the RTP stream MUST be 0), the transmission order of NAL units carried in the RTP stream
the same as the NAL unit decoding order. MUST be the same as the NAL unit decoding order.
* A NAL unit of small size SHOULD be encapsulated in an aggregation * A NAL unit of small size SHOULD be encapsulated in an AP together
packet together with one or more other NAL units to avoid the with one or more other NAL units to avoid the unnecessary
unnecessary packetization overhead for small NAL units. For packetization overhead for small NAL units. For example, non-VCL
example, non-VCL NAL units, such as access unit delimiters, NAL units, such as access unit delimiters, parameter sets, or SEI
parameter sets, or SEI NAL units, are typically small and can NAL units, are typically small and can often be aggregated with
often be aggregated with VCL NAL units without violating MTU size VCL NAL units without violating MTU size constraints.
constraints.
* Each non-VCL NAL unit SHOULD, when possible from an MTU size match * Each non-VCL NAL unit SHOULD, when possible from an MTU size match
viewpoint, be encapsulated in an aggregation packet with its viewpoint, be encapsulated in an AP with its associated VCL NAL
associated VCL NAL unit, as typically, a non-VCL NAL unit would be unit as, typically, a non-VCL NAL unit would be meaningless
meaningless without the associated VCL NAL unit being available. without the associated VCL NAL unit being available.
* For carrying precisely one NAL unit in an RTP packet, a single NAL * A single NAL unit packet MUST be used for carrying precisely one
unit packet MUST be used. NAL unit in an RTP packet.
6. De-packetization Process 6. De-packetization Process
The general concept behind de-packetization is to get the NAL units 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 out of the RTP packets in an RTP stream and pass them to the decoder
in the NAL unit decoding order. in the NAL unit decoding order.
The de-packetization process is implementation dependent. Therefore, 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 also be used as long as the output implementation. Other schemes may also be used as long as the output
for the same input is the same as the process described below. The 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 order output is the same when the set of output NAL units and their order
are both identical. Optimizations relative to the described are both identical. Optimizations relative to the described
algorithms are possible. algorithms are possible.
All normal RTP mechanisms related to buffer management apply. In 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 determine RTP sequence number and the RTP timestamp) are removed. To determine
the exact time for decoding, factors such as a possible intentional the exact time for decoding, factors such as a possible intentional
delay to allow for proper inter-stream synchronization, MUST be delay to allow for proper inter-stream synchronization MUST be
factored in. considered.
NAL units with NAL unit type values in the range of 0 to 55, NAL units with NAL unit type values in the range of 0 to 55,
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 56 to 62, inclusive, MUST with NAL unit type values in the range of 56 to 62, inclusive, MUST
NOT be passed to the decoder. NOT be passed to the decoder.
The receiver includes a receiver buffer, which is used to compensate The receiver includes a receiver buffer, which is used to compensate
for transmission delay jitter within individual RTP streams and to for transmission delay jitter within individual RTP streams and to
reorder NAL units from transmission order to the NAL unit decoding reorder NAL units from transmission order to the NAL unit decoding
order. In this section, the receiver operation is described under order. In this section, the receiver operation is described under
the assumption that there is no transmission delay jitter within an the assumption that there is no transmission delay jitter within an
RTP stream. To clarify the distinction from a practical receiver RTP stream. To clarify the distinction from a practical receiver
buffer, which is also used to compensate for transmission delay buffer, which is also used to compensate for transmission delay
jitter, the buffer in this section will henceforth be referred to as jitter, the buffer in this section will henceforth be referred to as
the de-packetization buffer. Receivers should also prepare for the "de-packetization" buffer. Receivers should also prepare for
transmission delay jitter; that is, either reserve separate buffers transmission delay jitter; that is, either reserve separate buffers
for transmission delay jitter buffering and de-packetization for transmission delay jitter buffering and de-packetization
buffering or use a receiver buffer for both transmission delay jitter buffering, or use a receiver buffer for both transmission delay
and de-packetization. Moreover, receivers should take transmission jitter and de-packetization. Moreover, receivers should take
delay jitter into account in the buffering operation, e.g., by transmission delay jitter into account in the buffering operation,
additional initial buffering before starting of decoding and e.g., by additional initial buffering before starting decoding and
playback. playback.
The de-packetization process extracts the NAL units from the RTP The de-packetization process extracts the NAL units from the RTP
packets in an RTP stream as follows. When an RTP packet carries a packets in an RTP stream as follows. When an RTP packet carries a
single NAL unit packet, the payload of the RTP packet is extracted as single NAL unit packet, the payload of the RTP packet is extracted as
a single NAL unit, excluding the DONL field, i.e., third and fourth a single NAL unit, excluding the DONL field, i.e., third and fourth
bytes, when sprop-max-don-diff is greater than 0. When an RTP packet bytes, when sprop-max-don-diff is greater than 0. When an RTP packet
carries an aggregation packet, several NAL units are extracted from carries an AP, several NAL units are extracted from the payload of
the payload of the RTP packet. In this case, each NAL unit the RTP packet. In this case, each NAL unit corresponds to the part
corresponds to the part of the payload of each aggregation unit that of the payload of each aggregation unit that follows the NALU size
follows the NALU size field, as described in Section 4.3.2. When an field, as described in Section 4.3.2. When an RTP packet carries a
RTP packet carries a Fragmentation Unit (FU), all RTP packets from Fragmentation Unit (FU), all RTP packets from the first FU (with the
the first FU (with the S field equal to 1) of the fragmented NAL unit S field equal to 1) of the fragmented NAL unit up to the last FU
up to the last FU (with the E field equal to 1) of the fragmented NAL (with the E field equal to 1) of the fragmented NAL unit are
unit are collected. The NAL unit is extracted from these RTP packets collected. The NAL unit is extracted from these RTP packets by
by concatenating all FU payloads in the same order as the concatenating all FU payloads in the same order as the corresponding
corresponding RTP packets and appending the NAL unit header with the RTP packets and appending the NAL unit header with the fields F and
fields F and TID set to equal the values of the fields F and TID in TID set to equal the values of the fields F and TID in the payload
the payload header of the FUs, respectively, and with the NAL unit header of the FUs, respectively, and with the NAL unit type set equal
type set equal to the value of the field FuType in the FU header of to the value of the field FuType in the FU header of the FUs, as
the FUs, as described in Section 4.3.3. described in Section 4.3.3.
When sprop-max-don-diff is equal to 0, the de-packetization buffer 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 size is zero bytes, and the NAL units carried in the single RTP
stream are directly passed to the decoder in their transmission stream are directly passed to the decoder in their transmission
order, which is identical to their decoding order. order, which is identical to their decoding order.
When sprop-max-don-diff is greater than 0, the process described in When sprop-max-don-diff is greater than 0, the process described in
the remainder of this section applies. the remainder of this section applies.
The receiver has two buffering states: initial buffering and The receiver has two buffering states: initial buffering and
skipping to change at page 30, line 5 skipping to change at line 1349
Initial buffering lasts until the difference between the greatest and Initial buffering lasts until the difference between the greatest and
smallest AbsDon values of the NAL units in the de-packetization smallest AbsDon values of the NAL units in the de-packetization
buffer is greater than or equal to the value of sprop-max-don-diff. buffer is greater than or equal to the value of sprop-max-don-diff.
After initial buffering, whenever the difference between the greatest After initial buffering, whenever the difference between the greatest
and smallest AbsDon values of the NAL units in the de-packetization and smallest AbsDon values of the NAL units in the de-packetization
buffer is greater than or equal to the value of sprop-max-don-diff, buffer is greater than or equal to the value of sprop-max-don-diff,
the following operation is repeatedly applied until this difference the following operation is repeatedly applied until this difference
is smaller than sprop-max-don-diff: is smaller than sprop-max-don-diff:
* The NAL unit in the de-packetization buffer with the smallest 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. passed to the decoder.
When no more NAL units are flowing into the de-packetization buffer, 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. AbsDon values.
7. Payload Format Parameters 7. Payload Format Parameters
This section specifies the optional parameters. A mapping of the This section specifies the optional parameters. A mapping of the
parameters with Session Description Protocol (SDP) [RFC8866] is also parameters with the Session Description Protocol (SDP) [RFC8866] is
provided for applications that use SDP. also provided for applications that use SDP.
Parameters starting with the string "sprop" for stream properties can Parameters starting with the string "sprop" for stream properties can
be used by a sender to provide a receiver with the properties of the be 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 stream that is or will be sent. The media sender (and not the
receiver) selects whether, and with what values, "sprop" parameters receiver) selects whether, and with what values, "sprop" parameters
are being sent. This uncommon characteristic of the "sprop" are being sent. This uncommon characteristic of the "sprop"
parameters may not be intuitive in the context of some signaling parameters may not be intuitive in the context of some signaling
protocol concepts, especially with offer/answer. Please see protocol concepts, especially with offer/answer. Please see
Section 7.3.2 for guidance specific to the use of sprop parameters in Section 7.3.2 for guidance specific to the use of sprop parameters in
the Offer/Answer case. the Offer/Answer case.
7.1. Media Type Registration 7.1. Media Type Registration
The receiver MUST ignore any parameter unspecified in this document. The receiver MUST ignore any parameter unspecified in this document.
Type name: video Type name: video
Subtype name: evc
Required parameters: N/A
Optional parameters: profile-id, level-id, toolset-id, max-recv-
level-id, sprop-sps, sprop-pps, sprop-sei, sprop-max-don-diff, sprop-
depack-buf-bytes, depack-buf-cap (refer to Section 7.2 for
definitions)
Encoding considerations:
This type is only defined for transfer via RTP (RFC 3550). Subtype name: evc
Security considerations: Required parameters: N/A
See Section 9 of RFC XXXX. Optional parameters: profile-id, level-id, toolset-id, max-recv-
level-id, sprop-sps, sprop-pps, sprop-sei, sprop-max-don-diff,
sprop-depack-buf-bytes, depack-buf-cap (refer to Section 7.2 for
definitions)
Interoperability considerations: N/A Encoding considerations: This type is only defined for transfer via
RTP [RFC3550].
Published specification: Security considerations: See Section 9 of RFC 9584.
Please refer to RFC XXXX and EVC standard [EVC]. Interoperability considerations: N/A
Applications that use this media type: Published specification: Please refer to RFC 9584 and EVC standard
[EVC].
Any application that relies on EVC-based video services over RTP Applications that use this media type: Any application that relies
on EVC-based video services over RTP
Fragment identifier considerations: N/A Fragment identifier considerations: N/A
Additional information: N/A Additional information: N/A
Person & email address to contact for further information: Person & email address to contact for further information:
Stephan Wenger (stewe@stewe.org) Stephan Wenger (stewe@stewe.org)
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: N/A
Author: See Authors' Addresses section of RFC XXXX. Restrictions on usage: N/A
Change controller: Author: See Authors' Addresses section of RFC 9584.
IETF <avtcore@ietf.org> Change controller: IETF <avtcore@ietf.org>
7.2. Optional Parameters Definition 7.2. Optional Parameters Definition
profile-id, level-id, toolset-id: profile-id, level-id, toolset-id:
These parameters indicate the profile, the level, and constraints These parameters indicate the profile, the level, and constraints
of the bitstream carried by the RTP stream, or a specific set of of the bitstream carried by the RTP stream or a specific set of
the profile, the level, and constraints the receiver supports. the profile, the level, and constraints the receiver supports.
More specifications of these parameters, including how they relate More specifications of these parameters, including how they relate
to syntax elements specified in [EVC] are provided below. to syntax elements specified in [EVC] are provided below.
profile-id: profile-id:
When profile-id is not present, a value of 0 (i.e., the Baseline When profile-id is not present, a value of 0 (i.e., the Baseline
profile) MUST be inferred. profile) MUST be inferred.
When used to indicate properties of a bitstream, profile-id MUST When used to indicate properties of a bitstream, profile-id MUST
be derived from the profile_idc in the SPS. be derived from the profile_idc in the SPS.
EVC bitstreams transported over RTP using the technologies of this EVC bitstreams transported over RTP using the technologies of this
document SHOULD refer only to SPSs that have the same value in document SHOULD refer only to SPSs that have the same value in
profile_idc, unless the sender has a priori knowledge that a profile_idc, unless the sender has a priori knowledge that a
receiver can correctly decode the EVC bitstream with different receiver can correctly decode the EVC bitstream with different
profile_idc values (for example in walled garden scenarios). As profile_idc values (for example, in walled garden scenarios). As
exceptions to this rule, if the receiver is known to support exceptions to this rule, if the receiver is known to support a
Baseline profile, a bitstream could safely end with CVS referring Baseline profile, a bitstream could safely end with CVS referring
to an SPS wherein profile_idc indicates the Baseline Still Picture to an SPS wherein profile_idc indicates the Baseline Still picture
profile. A similar exception can be made for Main profile and profile. A similar exception can be made for Main profile and
Main Still picture profile. Main Still picture profile.
level-id: level-id:
When level-id is not present, a value of 90 (corresponding to When level-id is not present, a value of 90 (corresponding to
level 3, which allows for approximately SD TV resolution and frame level 3, which allows for approximately SD TV resolution and frame
rates; for details please see Annex A of EVC) MUST be inferred. rates; see Annex A of [EVC]) MUST be inferred.
When used to indicate properties of a bitstream, level-id MUST be When used to indicate properties of a bitstream, level-id MUST be
derived from the level_idc in the SPS. derived from the level_idc in the SPS.
If the level-id parameter is used for capability exchange, the If the level-id parameter is used for capability exchange, the
following applies. If max-recv-level-id is not present, the following applies. If max-recv-level-id is not present, the
default level defined by level-id indicates the highest level the default level defined by level-id indicates the highest level the
codec wishes to support. Otherwise, max-recv-level-id indicates codec wishes to support. Otherwise, max-recv-level-id indicates
the highest level the codec supports for receiving. For either the highest level the codec supports for receiving. For either
receiving or sending, all levels that are lower than the highest receiving or sending, all levels that are lower than the highest
level supported MUST also be supported. level supported MUST also be supported.
toolset-id: toolset-id:
This parameter is a base64-encoding representation (Section 4 of
This parameter is a base64 encoding (Section 4 of [RFC4648]) [RFC4648]) of a 64-bit unsigned integer bit mask derived from the
representation of a 64 bit unsigned integer bit mask derived from concatenation, in network byte order, of the syntax elements
the concatenation, in network byte order, of the syntax elements
toolset_idc_h and toolset_idc_l. When used to indicate properties toolset_idc_h and toolset_idc_l. When used to indicate properties
of a bitstream, its value MUST be derived from toolset_idh_h and of a bitstream, its value MUST be derived from toolset_idh_h and
toolset_idc_l in the sequence parameter set. toolset_idc_l in the sequence parameter set.
max-recv-level-id: max-recv-level-id:
This parameter MAY be used to indicate the highest level a This parameter MAY be used to indicate the highest level a
receiver supports. receiver supports.
The value of max-recv-level-id MUST be in the range of 0 to 255, The value of max-recv-level-id MUST be in the range of 0 to 255,
inclusive.P. inclusive.
When max-recv-level-id is not present, the value is inferred to be When max-recv-level-id is not present, the value is inferred to be
equal to level-id. equal to level-id.
max-recv-level-id MUST NOT be present when the highest level the max-recv-level-id MUST NOT be present when the highest level the
receiver supports is not higher than the default level. receiver supports is not higher than the default level.
sprop-sps: sprop-sps:
This parameter MAY be used to convey sequence parameter set NAL This parameter MAY be used to convey sequence parameter set NAL
units of the bitstream for out-of-band transmission of sequence units of the bitstream for out-of-band transmission of sequence
parameter sets. The value of the parameter is a comma-separated parameter sets. The value of the parameter is a comma-separated
(',') list of base64 encoding (Section 4 of [RFC4648]) (',') list of base64-encoding representations (Section 4 of
representations of the sequence parameter set NAL units as [RFC4648]) of the sequence parameter set NAL units as specified in
specified in Section 7.3.2.1 of [EVC]. Section 7.3.2.1 of [EVC].
sprop-pps: sprop-pps:
This parameter MAY be used to convey picture parameter set NAL This parameter MAY be used to convey picture parameter set NAL
units of the bitstream for out-of-band transmission of picture units of the bitstream for out-of-band transmission of picture
parameter sets. The value of the parameter is a comma-separated parameter sets. The value of the parameter is a comma-separated
(',') list of base64 encoding (Section 4 of [RFC4648]) (',') list of base64-encoding representations (Section 4 of
representations of the picture parameter set NAL units as [RFC4648]) of the picture parameter set NAL units as specified in
specified in Section 7.3.2.2 of [EVC]. Section 7.3.2.2 of [EVC].
sprop-sei: sprop-sei:
This parameter MAY be used to convey one or more SEI messages that This parameter MAY be used to convey one or more SEI messages that
describe bitstream characteristics. When present, a decoder can describe bitstream characteristics. When present, a decoder can
rely on the bitstream characteristics that are described in the rely on the bitstream characteristics that are described in the
SEI messages for the entire duration of the session, independently SEI messages for the entire duration of the session, independently
from the persistence scopes of the SEI messages as specified in from the persistence scopes of the SEI messages as specified in
[VSEI]. [VSEI].
The value of the parameter is a comma-separated (',') list of The value of the parameter is a comma-separated (',') list of
base64 encoding (Section 4 of [RFC4648]) representations of SEI base64-encoding representations (Section 4 of [RFC4648]) of SEI
NAL units as specified in [VSEI]. NAL units as specified in [VSEI].
Informative note: Intentionally, no list of applicable or | Informative note: Intentionally, no list of applicable or
inapplicable SEI messages is specified here. Conveying certain | inapplicable SEI messages is specified here. Conveying
SEI messages in sprop-sei may be sensible in some application | certain SEI messages in sprop-sei may be sensible in some
scenarios and meaningless in others. However, a few examples | application scenarios and meaningless in others. However, a
are described below: | couple of examples are described below.
|
1) In an environment where the bitstream was created from film- | 1. In an environment where the bitstream was created from
based source material, and no splicing is going to occur during | film-based source material, and no splicing is going to
the lifetime of the session, the film grain characteristics SEI | occur during the lifetime of the session, the film grain
message is likely meaningful, and sending it in sprop-sei | characteristics SEI message is likely meaningful; and
rather than in the bitstream at each entry point may help with | sending it in sprop-sei rather than in the bitstream at
saving bits and allows one to configure the renderer only once, | each entry point may help with saving bits and allow one
avoiding unwanted artifacts. | to configure the renderer only once, avoiding unwanted
| artifacts.
2) Examples for SEI messages that would be meaningless to be |
conveyed in sprop-sei include the decoded picture hash SEI | 2. Examples for SEI messages that would be meaningless to
message (it is close to impossible that all decoded pictures | be conveyed in sprop-sei include the decoded picture
have the same hashtag) or the filler payload SEI message (as | hash SEI message (it is close to impossible that all
there is no point in just having more bits in SDP). | decoded pictures have the same hashtag) or the filler
| payload SEI message (as there is no point in just having
| more bits in SDP).
sprop-max-don-diff: sprop-max-don-diff:
If there is no NAL unit naluA that is followed in transmission 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 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 transmission order of the NAL units is the same as the decoding
order), the value of this parameter MUST be equal to 0. order), the value of this parameter MUST be equal to 0.
Otherwise, this parameter specifies the maximum absolute Otherwise, this parameter specifies the maximum absolute
difference between the decoding order number (i.e., AbsDon) values difference between the decoding order number (i.e., AbsDon) values
of any two NAL units naluA and naluB, where naluA follows naluB in of any two NAL units naluA and naluB, where naluA follows naluB in
decoding order and precedes naluB in transmission order. decoding order and precedes naluB in transmission order.
skipping to change at page 34, line 30 skipping to change at line 1550
of any two NAL units naluA and naluB, where naluA follows naluB in of any two NAL units naluA and naluB, where naluA follows naluB in
decoding order and precedes naluB in transmission order. decoding order and precedes naluB in transmission order.
The value of sprop-max-don-diff MUST be an integer in the range of The value of sprop-max-don-diff MUST be an integer in the range of
0 to 32767, inclusive. 0 to 32767, inclusive.
When not present, the value of sprop-max-don-diff is inferred to When not present, the value of sprop-max-don-diff is inferred to
be equal to 0. be equal to 0.
sprop-depack-buf-bytes: sprop-depack-buf-bytes:
This parameter signals the required size of the de-packetization This parameter signals the required size of the de-packetization
buffer in units of bytes. The value of the parameter MUST be buffer in units of bytes. The value of the parameter MUST be
greater than or equal to the maximum buffer occupancy (in units of greater than or equal to the maximum buffer occupancy (in units of
bytes) of the de-packetization buffer as specified in Section 6. bytes) of the de-packetization buffer as specified in Section 6.
The value of sprop-depack-buf-bytes MUST be an integer in the The value of sprop-depack-buf-bytes MUST be an integer in the
range of 0 to 4294967295, inclusive. range of 0 to 4294967295, inclusive.
When sprop-max-don-diff is present and greater than 0, this When sprop-max-don-diff is present and greater than 0, this
parameter MUST be present and the value MUST be greater than 0. parameter MUST be present and the value MUST be greater than 0.
When not present, the value of sprop-depack-buf-bytes is inferred When not present, the value of sprop-depack-buf-bytes is inferred
to be equal to 0. to be equal to 0.
Informative note: The value of sprop-depack-buf-bytes indicates | Informative note: The value of sprop-depack-buf-bytes
the required size of the de-packetization buffer only. When | indicates the required size of the de-packetization buffer
network jitter can occur, an appropriately sized jitter buffer | only. When network jitter can occur, an appropriately sized
has to be available as well. | jitter buffer has to be available as well.
depack-buf-cap: depack-buf-cap:
This parameter signals the capabilities of a receiver This parameter signals the capabilities of a receiver
implementation and indicates the amount of de-packetization buffer implementation and indicates the amount of de-packetization buffer
space in units of bytes that the receiver has available for space in units of bytes that the receiver has available for
reconstructing the NAL unit decoding order from NAL units carried reconstructing the NAL unit decoding order from NAL units carried
in the RTP stream. A receiver is able to handle any RTP stream 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 for which the value of the sprop-depack-buf-bytes parameter is
smaller than or equal to this parameter. smaller than or equal to this parameter.
When not present, the value of depack-buf-cap is inferred to be When not present, the value of depack-buf-cap is inferred to be
equal to 4294967295. The value of depack-buf-cap MUST be an equal to 4294967295. The value of depack-buf-cap MUST be an
integer in the range of 1 to 4294967295, inclusive. integer in the range of 1 to 4294967295, inclusive.
Informative note: depack-buf-cap indicates the maximum possible | Informative note: depack-buf-cap indicates the maximum
size of the de-packetization buffer of the receiver only, | possible size of the de-packetization buffer of the receiver
without allowing for network jitter. | only, without allowing for network jitter.
7.3. SDP Parameters 7.3. SDP Parameters
The receiver MUST ignore any parameter unspecified in this document. The receiver MUST ignore any parameter unspecified in this document.
7.3.1. Mapping of Payload Type Parameters to SDP 7.3.1. Mapping of Payload Type Parameters to SDP
The media type video/evc string is mapped to fields in the Session The media type video/evc string is mapped to fields in the Session
Description Protocol (SDP) [RFC8866] as follows: Description Protocol (SDP) [RFC8866] as follows:
* The media name in the "m=" line of SDP MUST be video. * The media name in the "m=" line of SDP MUST be video.
* The encoding name in the "a=rtpmap" line of SDP MUST be evc (the * The encoding name in the "a=rtpmap" line of SDP MUST be evc (the
media subtype). media subtype).
* The clock rate in the "a=rtpmap" line MUST be 90000. * The clock rate in the "a=rtpmap" line MUST be 90000.
* The OPTIONAL parameters profile-id, level-id, toolset-id, max- * The OPTIONAL parameters profile-id, level-id, toolset-id, max-
recv-level-id, sprop-max-don-diff, sprop-depack-buf-bytes, and recv-level-id, sprop-max-don-diff, sprop-depack-buf-bytes, and
depack-buf-cap, when present, MUST be included in the "a=fmtp" depack-buf-cap, when present, MUST be included in the "a=fmtp"
line of SDP. The fmtp line is expressed as a media type string, line of SDP. The "fmtp" line is expressed as a media type string,
in the form of a semicolon-separated list of parameter=value in the form of a semicolon-separated list of parameter=value
pairs. pairs.
* The OPTIONAL parameters sprop-sps, sprop-pps, and sprop-sei, when * The OPTIONAL parameters sprop-sps, sprop-pps, and sprop-sei, when
present, MUST be included in the "a=fmtp" line of SDP or conveyed present, MUST be included in the "a=fmtp" line of SDP or conveyed
using the "fmtp" source attribute as specified in Section 6.3 of using the "fmtp" source attribute as specified in Section 6.3 of
[RFC5576]. For a particular media format (i.e., RTP payload [RFC5576]. For a particular media format (i.e., RTP payload
type), sprop-sps, sprop-pps, or sprop-sei MUST NOT be both type), sprop-sps, sprop-pps, or sprop-sei MUST NOT be both
included in the "a=fmtp" line of SDP and conveyed using the "fmtp" included in the "a=fmtp" line of SDP and conveyed using the "fmtp"
source attribute. When included in the "a=fmtp" line of SDP, source attribute. When included in the "a=fmtp" line of SDP,
those parameters are expressed as a media type string, in the form those parameters are expressed as a media type string, in the form
of a semicolon-separated list of parameter=value pairs. When of a semicolon-separated list of parameter=value pairs. When
conveyed in the "a=fmtp" line of SDP for a particular payload conveyed in the "a=fmtp" line of SDP for a particular payload
type, the parameters sprop-sps, sprop-pps, and sprop-sei MUST be type, the parameters sprop-sps, sprop-pps, and sprop-sei MUST be
applied to each SSRC with the payload type. When conveyed using applied to each SSRC with the payload type. When conveyed using
the "fmtp" source attribute, these parameters are only associated the "fmtp" source attribute, these parameters are only associated
with the given source and payload type as parts of the "fmtp" with the given source and payload type as parts of the "fmtp"
source attribute. source attribute.
Informative note: Conveyance of sprop-sps and sprop-pps using the | Informative note: Conveyance of sprop-sps and sprop-pps using
"fmtp" source attribute allows for out-of-band transport of | the "fmtp" source attribute allows for out-of-band transport of
parameter sets in topologies like Topo-Video-switch-MCU, as | parameter sets in topologies like Topo-Video-switch-MCU, as
specified in [RFC7667]. | specified in [RFC7667].
A general usage of media representation in SDP is as follows: A general usage of media representation in SDP is as follows:
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 evc/90000 a=rtpmap:98 evc/90000
a=fmtp:98 profile-id=1; a=fmtp:98 profile-id=1;
sprop-sps=<sequence parameter set data>; sprop-sps=<sequence parameter set data>;
sprop-pps=<picture parameter set data>; sprop-pps=<picture parameter set data>;
A SIP offer/answer exchange wherein both parties are expected to both A SIP offer/answer exchange wherein both parties are expected to both
send and receive could look like the following. Only the media send and receive could look like the following. Only the media
codec-specific parts of the SDP are shown. codec-specific parts of the SDP are shown.
Offerer->Answerer: Offerer->Answerer:
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 evc/90000 a=rtpmap:98 evc/90000
a=fmtp:98 profile-id=1; level_id=90; a=fmtp:98 profile-id=1; level_id=90;
The above represents an offer for symmetric video communication The above represents an offer for symmetric video communication using
using [EVC] and its payload specification at the main profile and [EVC] and its payload specification at the main profile and level
level 3.0. Informally speaking, this offer tells the receiver of 3.0. Informally speaking, this offer tells the receiver of the offer
the offer that the sender is willing to receive up to xKpxx that the sender is willing to receive up to xKpxx resolution at the
resolution at the maximum bitrates specified in [EVC]. At the maximum bitrates specified in [EVC]. At the same time, if this offer
same time, if this offer were accepted "as is", the offer can were accepted "as is", the offer can expect that the answerer would
expect that the answerer would be able to receive and properly be able to receive and properly decode EVC media up to and including
decode EVC media up to and including level 3.0. level 3.0.
Answerer->Offerer: Answerer->Offerer:
m=video 49170 RTP/AVP 98 m=video 49170 RTP/AVP 98
a=rtpmap:98 evc/90000 a=rtpmap:98 evc/90000
a=fmtp:98 profile-id=1; level_id=60 a=fmtp:98 profile-id=1; level_id=60
Informative note: level_id shall be set equal to a value of 30 | Informative note: level_id shall be set equal to a value of 30
times the level number specified in Table A.1 of EVC. | times the level number specified in Table A.1 of [EVC].
With this answer to the offer above, the system receiving the offer With this answer to the offer above, the system receiving the offer
advises the offerer that it is incapable of handing evc at level 3.0 advises the offerer that it is incapable of handling evc at level 3.0
but is capable of decoding level 2. As EVC video codecs must support but is capable of decoding level 2. As EVC video codecs must support
decoding at all levels below the maximum level they implement, the decoding at all levels below the maximum level they implement, the
resulting user experience would likely be that both systems send resulting user experience would likely be that both systems send
video at level 2. However, nothing prevents an encoder from further video at level 2. However, nothing prevents an encoder from further
downgrading its sending to, for example, level 1 if it were short of downgrading its sending to, for example, level 1 if it were short of
cycles or bandwidth or for other reasons. cycles or bandwidth or for other reasons.
7.3.2. Usage with SDP Offer/Answer Model 7.3.2. Usage with SDP Offer/Answer Model
This section describes the negotiation of unicast messages using the This section describes the negotiation of unicast messages using the
skipping to change at page 37, line 31 skipping to change at line 1689
The following limitations and rules pertaining to the media The following limitations and rules pertaining to the media
configuration apply: configuration apply:
The parameters identifying a media format configuration for EVC are The parameters identifying a media format configuration for EVC are
profile-id and level-id. Profile_id MUST be used symmetrically. profile-id and level-id. Profile_id MUST be used symmetrically.
The answerer MUST structure its answer according to one of the The answerer MUST structure its answer according to one of the
following three options: following three options:
- maintain all configuration parameters with the values remaining * maintain all configuration parameters with the values remaining
the same as in the offer for the media format (payload type), the same as in the offer for the media format (payload type), with
with the exception that the value of level-id is changeable as the exception that the value of level-id is changeable as long as
long as the highest level indicated by the answer is not higher the highest level indicated by the answer is not higher than that
than that indicated by the offer; or indicated by the offer; or
- remove the media format (payload type) completely (when one or * remove the media format (payload type) completely (when one or
more of the parameter values are not supported). more of the parameter values are not supported).
Informative note: The above requirement for symmetric use does not | Informative note: The above requirement for symmetric use does
apply for level-id and does not apply for the other bitstream or RTP | not apply for level-id and does not apply for the other
stream properties and capability parameters, as described in | bitstream or RTP stream properties and capability parameters,
Section 7.3.2.1 (Payload format config) below. | as described in Section 7.3.2.1 ("Payload Format
| Configuration").
To simplify handling and matching of these configurations, the same To simplify handling and matching of these configurations, the same
RTP payload type number used in the offer SHOULD also be used in the RTP payload type number used in the offer SHOULD also be used in the
answer, as specified in [RFC3264]. answer, as specified in [RFC3264].
The answer MUST NOT contain a payload type number used in the offer The answer MUST NOT contain a payload type number used in the offer
for the media subtype unless the configuration is the same as in the for the media subtype unless the configuration is the same as in the
offer or the configuration in the answer only differs from that in offer or the configuration in the answer only differs from that in
the offer with a different value of level-id. the offer with a different value of level-id.
skipping to change at page 38, line 19 skipping to change at line 1727
The parameters sprop-max-don-diff and sprop-depack-buf-bytes describe The parameters sprop-max-don-diff and sprop-depack-buf-bytes describe
the properties of an RTP stream that the offerer or the answerer is the properties of an RTP stream that the offerer or the answerer is
sending for the media format configuration. This differs from the sending for the media format configuration. This differs from the
normal usage of the offer/answer parameters; normally, such normal usage of the offer/answer parameters; normally, such
parameters declare the properties of the bitstream or RTP stream that parameters declare the properties of the bitstream or RTP stream that
the offerer or the answerer is able to receive. When dealing with the offerer or the answerer is able to receive. When dealing with
EVC, the offerer assumes that the answerer will be able to receive EVC, the offerer assumes that the answerer will be able to receive
media encoded using the configuration being offered. media encoded using the configuration being offered.
Informative note: The above parameters apply for any RTP stream, when | Informative note: The above parameters apply for any RTP
present, sent by a declaring entity with the same configuration. In | stream, when present, sent by a declaring entity with the same
other words, the applicability of the above parameters to RTP streams | configuration. In other words, the applicability of the above
depends on the source endpoint. Rather than being bound to the | parameters to RTP streams depends on the source endpoint.
payload type, the values may have to be applied to another payload | Rather than being bound to the payload type, the values may
type when being sent, as they apply for the configuration. | have to be applied to another payload type when being sent, as
| they apply for the configuration.
When an offerer offers an interleaved stream, indicated by the When an offerer offers an interleaved stream, indicated by the
presence of sprop-max-don-diff with a value larger than zero, the presence of sprop-max-don-diff with a value larger than zero, the
offerer MUST include the size of the de-packetization buffer sprop- offerer MUST include the size of the de-packetization buffer sprop-
depack-buf-bytes. depack-buf-bytes.
To enable the offerer and answerer to inform each other about their To enable the offerer and answerer to inform each other about their
capabilities for de-packetization buffering in receiving RTP streams, capabilities for de-packetization buffering in receiving RTP streams,
both parties are RECOMMENDED to include depack-buf-cap. both parties are RECOMMENDED to include depack-buf-cap.
The parameters sprop-sps, or sprop-pps, when present (included in the The parameters sprop-sps or sprop-pps, when present (included in the
"a=fmtp" line of SDP or conveyed using the "fmtp" source attribute, "a=fmtp" line of SDP or conveyed using the "fmtp" source attribute,
as specified in Section 6.3 of [RFC5576]), are used for out-of-band as specified in Section 6.3 of [RFC5576]), are used for out-of-band
transport of the parameter sets (SPS or PPS, respectively). The transport of the parameter sets (SPS or PPS, respectively). The
answerer MAY use either out-of-band or in-band transport of parameter answerer MAY use either out-of-band or in-band transport of parameter
sets for the bitstream it is sending, regardless of whether out-of- sets for the bitstream it is sending, regardless of whether out-of-
band parameter sets transport has been used in the offerer-to- band parameter sets transport has been used in the offerer-to-
answerer direction. Parameter sets included in an answer are answerer direction. Parameter sets included in an answer are
independent of those parameter sets included in the offer, as they independent of those parameter sets included in the offer, as they
are used for decoding two different bitstreams; one from the answerer are used for decoding two different bitstreams: one from the answerer
to the offerer and the other in the opposite direction. In case some to the offerer, and the other in the opposite direction. In case
RTP packets are sent before the SDP offer/answer settles down, in- some RTP packets are sent before the SDP offer/answer settles down,
band parameter sets MUST be used for those RTP stream parts sent in-band parameter sets MUST be used for those RTP stream parts sent
before the SDP offer/answer. before the SDP offer/answer.
The following rules apply to transport of parameter sets in the The following rules apply to transport of parameter sets in the
offerer-to-answerer direction. offerer-to-answerer direction.
An offer MAY include sprop-sps, and/or sprop-pps. If none of these An offer MAY include sprop-sps and/or sprop-pps. If none of these
parameters are present in the offer, then only in-band transport of parameters are present in the offer, then only in-band transport of
parameter sets is used. parameter sets is used.
If the level to use in the offerer-to-answerer direction is equal to 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 default level in the offer, the answerer MUST be prepared to use
the parameter sets included in sprop-sps, and sprop-pps (either the parameter sets included in sprop-sps and sprop-pps (either
included in the "a=fmtp" line of SDP or conveyed using the "fmtp" included in the "a=fmtp" line of SDP or conveyed using the "fmtp"
source attribute) for decoding the incoming bitstream, e.g., by source attribute) for decoding the incoming bitstream, e.g., by
passing these parameter set NAL units to the video decoder before passing these parameter set NAL units to the video decoder before
passing any NAL units carried in the RTP streams. Otherwise, the passing any NAL units carried in the RTP streams. Otherwise, the
answerer MUST ignore sprop-vps, sprop-sps, and sprop-pps (either answerer MUST ignore sprop-vps, sprop-sps, and sprop-pps (either
included in the "a=fmtp" line of SDP or conveyed using the "fmtp" included in the "a=fmtp" line of SDP or conveyed using the "fmtp"
source attribute) and the offerer MUST transmit parameter sets in- source attribute), and the offerer MUST transmit parameter sets in-
band. band.
The following rules apply to transport of parameter sets in the The following rules apply to transport of parameter sets in the
answerer-to-offerer direction. answerer-to-offerer direction.
An answer MAY include sprop-sps, and/or sprop-pps. If none of these An answer MAY include sprop-sps and/or sprop-pps. If none of these
parameters are present in the answer, then only in-band transport of parameters are present in the answer, then only in-band transport of
parameter sets is used. parameter sets is used.
The offerer MUST be prepared to use the parameter sets included in The offerer MUST be prepared to use the parameter sets included in
sprop-sps and sprop-pps (either included in the "a=fmtp" line of SDP sprop-sps and sprop-pps (either included in the "a=fmtp" line of SDP
or conveyed using the "fmtp" source attribute) for decoding the or conveyed using the "fmtp" source attribute) for decoding the
incoming bitstream, e.g., by passing these parameter set NAL units to incoming bitstream, e.g., by passing these parameter set NAL units to
the video decoder before passing any NAL units carried in the RTP the video decoder before passing any NAL units carried in the RTP
streams. streams.
skipping to change at page 40, line 23 skipping to change at line 1825
sprop-max-don-diff P - P sprop-max-don-diff P - P
sprop-depack-buf-bytes P - P sprop-depack-buf-bytes P - P
depack-buf-cap R R - depack-buf-cap R R -
sprop-sei P - P sprop-sei P - P
sprop-sps P - P sprop-sps P - P
sprop-pps P - P sprop-pps P - P
Legend: Legend:
C: configuration for sending and receiving bitstreams C: configuration for sending and receiving bitstreams
D: changeable configuration, same as C, except possible to D: changeable configuration; same as C, except possible to
answer with a different but consistent value (see the semantics answer with a different but consistent value (see the semantics
of the level-id parameter on these parameters being of the level-id parameter on these parameters being
consistent-basically, level down-grading is allowed) consistent -- basically, level down-grading is allowed)
P: properties of the bitstream to be sent P: properties of the bitstream to be sent
R: receiver capabilities R: receiver capabilities
-: not usable, when present MUST be ignored -: not usable; when present MUST be ignored
Interpretation of Parameters for Various Combinations of
Offers, Answers, and Direction Attributes.
Figure 11 Figure 11: Interpretation of Parameters for Various Combinations
of Offers, Answers, and Direction Attributes
Parameters used for declaring receiver capabilities are, in general, Parameters used for declaring receiver capabilities are, in general,
downgradable, i.e., they express the upper limit for a sender's downgradable, i.e., they express the upper limit for a sender's
possible behavior. Thus, a sender MAY select to set its encoder possible behavior. Thus, a sender MAY select to set its encoder
using only lower/lesser or equal values of these parameters. using only lower/lesser or equal values of these parameters.
When a sender's capabilities are declared with the configuration 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
skipping to change at page 41, line 11 skipping to change at line 1857
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. payload type associated with the offer.
An implementation SHOULD be able to understand all media type An implementation SHOULD be able to understand all media type
parameters (including all optional media type parameters), even if it parameters (including all optional media type parameters), even if it
doesn't support the functionality related to the parameter. This, in doesn't support the functionality related to the parameter. This, in
conjunction with proper application logic in the implementation, conjunction with proper application logic in the implementation,
allows the implementation, after having received an offer, to create allows the implementation, after having received an offer, to create
an answer by potentially downgrading one or more of the optional an answer by potentially downgrading one or more of the optional
parameters to the point where the implementation can cope, leading to parameters to the point where the implementation can cope. This
higher chances of interoperability beyond the most basic interop leads to higher chances of interoperability beyond the most basic
points (for which, as described above, no optional parameters are interop points (for which, as described above, no optional parameters
necessary). are necessary).
Informative note: In implementations of various H.26x video coding | Informative note: In implementations of various H.26x video
payload Formats including those for [AVC] and [HEVC], it was | coding payload formats including those for [AVC] and [HEVC], it
occasionally observed that implementations were incapable of parsing | was occasionally observed that implementations were incapable
most (or all) of the optional parameters and hence rejected offers | of parsing most (or all) of the optional parameters and hence
other than the most basic offers. As a result, the offer/answer | rejected offers other than the most basic offers. As a result,
exchange resulted in a baseline performance (using the default values | the offer/answer exchange resulted in a baseline performance
for the optional parameters) with the resulting suboptimal user | (using the default values for the optional parameters) with the
experience. However, there are valid reasons to forego the | resulting suboptimal user experience. However, there are valid
implementation complexity of implementing the parsing of some or all | reasons to forego the implementation complexity of implementing
of the optional parameters, for example, when there is predetermined | the parsing of some or all of the optional parameters, for
knowledge, not negotiated by an SDP-based offer/answer process, of | example, when there is predetermined knowledge, not negotiated
the capabilities of the involved systems (walled gardens, baseline | by an SDP-based offer/answer process, of the capabilities of
requirements defined in application standards higher up in the stack, | the involved systems (walled gardens, baseline requirements
and similar). | defined in application standards higher up in the stack, and
| similar).
An answerer MAY extend the offer with additional media format 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. format configuration, and not only to send it.
7.3.3. Multicast 7.3.3. Multicast
For bitstreams being delivered over multicast, the following rules For bitstreams being delivered over multicast, the following rules
apply: apply:
The media format configuration is identified by profile-id and level- The media format configuration is identified by profile-id and level-
id. These media format configuration parameters, including level-id, id. These media format configuration parameters, including level-id,
MUST be used symmetrically; that is, the answerer MUST either MUST be used symmetrically; that is, the answerer MUST either
maintain all configuration parameters or remove the media format maintain all configuration parameters or remove the media format
skipping to change at page 42, line 21 skipping to change at line 1913
Parameter sets received MUST be associated with the originating Parameter sets received MUST be associated with the originating
source and MUST only be used in decoding the incoming bitstream from source and MUST only be used in decoding the incoming bitstream from
the same source. the same source.
The rules for other parameters are the same as above for unicast as The rules for other parameters are the same as above for unicast as
long as the three above rules are obeyed. long as the three above rules are obeyed.
7.3.4. Usage in Declarative Session Descriptions 7.3.4. Usage in Declarative Session Descriptions
When EVC over RTP is offered with SDP in a declarative style, as in When EVC over RTP is offered with SDP in a declarative style, as in
Real Time Streaming Protocol (RTSP) [RFC7826] or Session Announcement the Real-Time Streaming Protocol (RTSP) [RFC7826] or Session
Protocol (SAP) [RFC2974], the following considerations apply. Announcement Protocol (SAP) [RFC2974], the following considerations
apply.
All parameters capable of indicating both bitstream properties and All parameters capable of indicating both bitstream properties and
receiver capabilities are used to indicate only bitstream properties. receiver capabilities are used to indicate only bitstream properties.
For example, in this case, the parameters profile-id and level-id For example, in this case, the parameters profile-id and level-id
declare the values used by the bitstream, not the capabilities for declare the values used by the bitstream, not the capabilities for
receiving bitstreams. As a result, the following interpretation of receiving bitstreams. As a result, the following interpretation of
the parameters MUST be used: the parameters MUST be used:
Declaring actual configuration or bitstream properties: * Declaring actual configuration or bitstream properties:
profile-id level-id sprop-sps sprop-pps sprop-max-don-diff sprop- - profile-id
depack-buf-bytes sprop-sei - level-id
- sprop-sps
- sprop-pps
- sprop-max-don-diff
- sprop-depack-buf-bytes
- sprop-sei
Not usable (when present, they MUST be ignored): * Not usable (when present, they MUST be ignored):
depack-buf-cap recv-sublayer-id - depack-buf-cap
- recv-sublayer-id
A receiver of the SDP is required to support all parameters and * A receiver of the SDP is required to support all parameters and
values of the parameters provided; otherwise, the receiver MUST values of the parameters provided; otherwise, the receiver MUST
reject (RTSP) or not participate in (SAP) the session. It falls on reject (RTSP) or not participate in (SAP) the session. It falls
the creator of the session to use values that are expected to be on the creator of the session to use values that are expected to
supported by the receiving application. be supported by the receiving application.
7.3.5. Considerations for Parameter Sets 7.3.5. Considerations for Parameter Sets
When out-of-band transport of parameter sets is used, parameter sets When out-of-band transport of parameter sets is used, parameter sets
MAY still be additionally transported in-band unless explicitly MAY still be additionally transported in-band unless explicitly
disallowed by an application, and some of these additional parameter disallowed by an application, and some of these additional parameter
sets may update some of the out-of-band transported parameter sets. sets may update some of the out-of-band transported parameter sets.
An update of a parameter set refers to the sending of a parameter set An 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 different of the same type using the same parameter set ID but with different
values for at least one other parameter of the parameter set. values for at least one other parameter of the parameter set.
8. Use with Feedback Messages 8. Use with Feedback Messages
The following subsections define the use of the Picture Loss The following subsections define the use of the Picture Loss
Indication (PLI) and Full Intra Request (FIR) feedback messages with Indication (PLI) and Full Intra Request (FIR) feedback messages with
[EVC]. The PLI is defined in [RFC4585], and the FIR message is [EVC]. The PLI is defined in [RFC4585], and the FIR message is
defined in [RFC5104]. defined in [RFC5104].
In accordance with this document, a sender MUST NOT send Slice Loss In accordance with this document, a sender MUST NOT send Slice Loss
Indication (SLI) or Reference Picture Selection Indication (RPSI), Indication (SLI) or Reference Picture Selection Indication (RPSI);
and a receiver MUST ignore RPSI and MUST treat a received SLI as a and a receiver MUST ignore RPSI and MUST treat a received SLI as a
received PLI, ignoring the "First", "Number", and "PictureID" fields received PLI, ignoring the "First", "Number", and "PictureID" fields
of the PLI. of the PLI.
8.1. Picture Loss Indication (PLI) 8.1. Picture Loss Indication (PLI)
As specified in Section 6.3.1 of [RFC4585], the reception of a PLI by As specified in Section 6.3.1 of [RFC4585], the reception of a PLI by
a media sender indicates "the loss of an undefined amount of coded a 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, IDR picture locations, picture location of in-band parameter sets, IDR picture locations, picture
structures, and so forth), a reaction to the reception of a PLI by a structures, and so forth), a reaction to the reception of a PLI by an
EVC sender SHOULD be to send an IDR picture and relevant parameter EVC sender SHOULD be to send an IDR picture and relevant parameter
sets, potentially with sufficient redundancy so to ensure correct sets, potentially with sufficient redundancy so as to ensure correct
reception. However, sometimes information about the bitstream reception. However, sometimes information about the bitstream
structure is known. For example, such information can be parameter structure is known. For example, such information can be parameter
sets that have been conveyed out of band through mechanisms not sets that have been conveyed out of band through mechanisms not
defined in this document and that are known to stay static for the defined in this document and that are known to stay static for the
duration of the session. In that case, it is obviously unnecessary duration of the session. In that case, it is obviously unnecessary
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 [RFC4585] MUST be observed. congestion-control mechanisms of [RFC4585] MUST be observed.
8.2. Full Intra Request (FIR) 8.2. Full Intra Request (FIR)
The purpose of the FIR message is to force an encoder to send an The purpose of the FIR message is to force an encoder to send an
independent decoder refresh point as soon as possible while observing independent decoder refresh point as soon as possible while observing
applicable congestion-control-related constraints, such as those set applicable congestion-control-related constraints, such as those set
out in [RFC8082]. out in [RFC8082].
Upon reception of a FIR, a sender MUST send an IDR picture. Upon reception of a FIR, a sender MUST send an IDR picture.
Parameter sets MUST also be sent, except when there is a priori Parameter sets MUST also be sent, except when there is a priori
skipping to change at page 44, line 26 skipping to change at line 2009
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. sets are exclusively sent out of band.
9. Security Considerations 9. Security Considerations
The scope of this section is limited to the payload format itself and The scope of this section is limited to the payload format itself and
to one feature of [EVC] that may pose a particularly serious security to one feature of [EVC] that may pose a particularly serious security
risk if implemented naively. The payload format, in isolation, does risk if implemented naively. The payload format, in isolation, does
not form a complete system. Implementers are advised to read and not form a complete system. Implementers are advised to read and
understand relevant security-related documents, especially those understand relevant security-related documents, especially those
pertaining to RTP (see the Security Considerations section in pertaining to RTP (see the Security Considerations in Section 14 of
[RFC3550]) and the security of the call-control stack chosen (that [RFC3550]) and the security of the call-control stack chosen (that
may make use of the media type registration of this document). may make use of the media type registration of this document).
Implementers should also consider known security vulnerabilities of Implementers should also consider known security vulnerabilities of
video coding and decoding implementations in general and avoid those. video coding and decoding implementations in general and avoid those.
Within this RTP payload format, and with the exception of the user 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 document seem to pose a security risk beyond those part of this document seem to pose a security risk beyond those
common to all RTP-based systems. common to all RTP-based systems.
RTP packets using the payload format defined in this specification 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 [RFC3550], and in any applicable RTP profile such as specification [RFC3550] and in any applicable RTP profile such as
RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/ RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/
SAVPF [RFC5124]. However, as "Securing the RTP Framework: Why RTP SAVPF [RFC5124]. However, as "Securing the RTP Framework: Why RTP
Does Not Mandate a Single Media Security Solution" [RFC7202] Does Not Mandate a Single Media Security Solution" [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
in general. This responsibility lays on anyone using RTP in an RTP in general. This responsibility lies 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"
[RFC7201]. Applications SHOULD use one or more appropriate strong [RFC7201]. Applications SHOULD use one or more appropriate strong
security mechanisms. The rest of this section discusses the security security mechanisms. The rest of this section discusses the security
impacting properties of the payload format itself. impacting properties of the payload format itself.
Because the data compression used with this payload format is applied 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. receiver to be overloaded.
EVC is particularly vulnerable to such attacks, as it is extremely EVC is particularly vulnerable to such attacks, as it is extremely
simple to generate datagrams containing NAL units that affect the simple to generate datagrams containing NAL units that affect the
decoding process of many future NAL units. Therefore, the usage of decoding process of many future NAL units. Therefore, the usage of
data origin authentication and data integrity protection of at least data origin authentication and data integrity protection of at least
the RTP packet is RECOMMENDED based on the thoughts of [RFC7202]. the RTP packet is RECOMMENDED based on [RFC7202].
Like HEVC [RFC7798] and [VVC], [EVC] includes a user data Like HEVC [RFC7798] and VVC [VVC], EVC [EVC] includes a user data
Supplemental Enhancement Information (SEI) message. This SEI message Supplemental Enhancement Information (SEI) message. This SEI message
allows inclusion of an arbitrary bitstring into the video bitstream. allows inclusion of an arbitrary bitstring into the video bitstream.
Such a bitstring could include JavaScript, machine code, and other Such a bitstring could include JavaScript, machine code, and other
active content. active content.
[EVC] leaves the handling of this SEI message to the receiving EVC [EVC] leaves the handling of this SEI message to the receiving
system. In order to avoid harmful side effects of the user data SEI system. In order to avoid harmful side effects of the user data SEI
message, decoder implementations cannot naively trust its content. message, decoder implementations cannot naively trust its content.
For example, forwarding all received JavaScript code detected by a For example, forwarding all received JavaScript code detected by a
decoder implementation to a web-browser unchecked would be a bad and decoder implementation to a web browser unchecked would be a bad and
insecure implementation practice. The safest way to deal with user insecure implementation practice. The safest way to deal with user
data SEI messages is to simply discard them, but that can have data SEI messages is to simply discard them, but that can have
negative side effects on the quality of experience by the user. negative side effects on the quality of experience by the user.
End-to-end security with authentication, integrity, or 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
skipping to change at page 46, line 21 skipping to change at line 2087
Congestion control for RTP SHALL be used in accordance with RTP Congestion control for RTP SHALL be used in accordance with RTP
[RFC3550] and with any applicable RTP profile, e.g., AVP [RFC3551] or [RFC3550] and with any applicable RTP profile, e.g., AVP [RFC3551] or
AVPF [RFC4585]. If best-effort service is being used, an additional AVPF [RFC4585]. If best-effort service is being used, an additional
requirement is that users of this payload format MUST monitor packet requirement is that users of this payload format MUST monitor packet
loss to ensure that the packet loss rate is within an acceptable loss to ensure that the packet loss rate is within an acceptable
range. Packet loss is considered acceptable if a TCP flow across the range. Packet loss is considered acceptable if a TCP flow across the
same network path and experiencing the same network conditions would same network path and experiencing the same network conditions would
achieve an average throughput, measured on a reasonable timescale, achieve an average throughput, measured on a reasonable timescale,
that is not less than all RTP streams combined are achieved. This that is not less than all RTP streams combined are achieved. This
condition can be satisfied by implementing congestion-control condition can be satisfied by implementing congestion-control
mechanisms to adapt the transmission rate, by implementing the number mechanisms to adapt the transmission rate by implementing the number
of layers subscribed for a layered multicast session, or by arranging of layers subscribed for a layered multicast session or by arranging
for a receiver to leave the session if the loss rate is unacceptably for a receiver to leave the session if the loss rate is unacceptably
high. high.
The bitrate adaptation necessary for obeying the congestion control 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. However, example, by adequately tuning the quantization parameter. However,
when pre-encoded content is being transmitted, bandwidth adaptation when pre-encoded content is being transmitted, bandwidth adaptation
requires the pre-coded bitstream to be tailored for such adaptivity. requires the pre-coded bitstream to be tailored for such adaptivity.
The key mechanism available in [EVC] is temporal scalability. A The key mechanism available in [EVC] is temporal scalability. A
media sender can remove NAL units belonging to higher temporal sub- media sender can remove NAL units belonging to higher temporal sub-
layers (i.e., those NAL units with a large value of TID) until the layers (i.e., those NAL units with a large value of TID) until the
sending bitrate drops to an acceptable range. sending bitrate drops to an acceptable range.
The mechanisms mentioned above generally work within a defined The mechanisms mentioned above generally work within a defined
profile and level; therefore no renegotiation of the channel is profile and level; therefore, no renegotiation of the channel is
required. Only when non-downgradable parameters (such as profile) required. Only when non-downgradable parameters (such as the
are required to be changed does it become necessary to terminate and profile) are required to be changed does it become necessary to
restart the RTP stream(s). This may be accomplished by using terminate and restart the RTP streams. This may be accomplished by
different RTP payload types. using different RTP payload types.
MANEs MAY remove certain unusable packets from the RTP stream when MANEs MAY remove certain unusable packets from the RTP stream 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, because the trailing FUs are same NAL unit have been lost, because the trailing FUs 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. viewpoint) experiences congestion.
11. IANA Considerations 11. IANA Considerations
A new media type, as specified in Section 7.1 of this document, has The media type specified in Section 7.1 has been registered with
been registered with IANA. IANA.
12. Acknowledgements
Large parts of this specification share text with the RTP payload
format for VVC [RFC9328]. Roman Chernyak is thanksed for his
valueable review comments. We thank the authors of that
specification for their excellent work.
13. References 12. References
13.1. Normative References 12.1. Normative References
[EVC] "ISO/IEC 23094-1 Essential Video Coding", 2020, [EVC] "Information technology -- General video coding -- Part 1:
<https://www.iso.org/standard/57797.html>. Essential video coding", ISO/IEC 23094-1:2020, October
2020, <https://www.iso.org/standard/57797.html>.
[ISO23094-1] [ISO23094-1]
"ISO/IEC DIS Information technology --- General video "Information technology - General video coding - Part 1:
coding --- Part 1 Essential video coding", n.d., Essential video coding", ISO/IEC 23094-1:2020, October
<https://www.iso.org/standard/57797.html>. 2020, <https://www.iso.org/standard/57797.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/rfc/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/rfc/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551, Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003, DOI 10.17487/RFC3551, July 2003,
<https://www.rfc-editor.org/rfc/rfc3551>. <https://www.rfc-editor.org/info/rfc3551>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<https://www.rfc-editor.org/rfc/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control "Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006, DOI 10.17487/RFC4585, July 2006,
<https://www.rfc-editor.org/rfc/rfc4585>. <https://www.rfc-editor.org/info/rfc4585>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>. <https://www.rfc-editor.org/info/rfc4648>.
[RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
"Codec Control Messages in the RTP Audio-Visual Profile "Codec Control Messages in the RTP Audio-Visual Profile
with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104, with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
February 2008, <https://www.rfc-editor.org/rfc/rfc5104>. February 2008, <https://www.rfc-editor.org/info/rfc5104>.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
2008, <https://www.rfc-editor.org/rfc/rfc5124>. 2008, <https://www.rfc-editor.org/info/rfc5124>.
[RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific
Media Attributes in the Session Description Protocol Media Attributes in the Session Description Protocol
(SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009, (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009,
<https://www.rfc-editor.org/rfc/rfc5576>. <https://www.rfc-editor.org/info/rfc5576>.
[RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M., [RFC7826] Schulzrinne, H., Rao, A., Lanphier, R., Westerlund, M.,
and M. Stiemerling, Ed., "Real-Time Streaming Protocol and M. Stiemerling, Ed., "Real-Time Streaming Protocol
Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December Version 2.0", RFC 7826, DOI 10.17487/RFC7826, December
2016, <https://www.rfc-editor.org/rfc/rfc7826>. 2016, <https://www.rfc-editor.org/info/rfc7826>.
[RFC8082] Wenger, S., Lennox, J., Burman, B., and M. Westerlund, [RFC8082] Wenger, S., Lennox, J., Burman, B., and M. Westerlund,
"Using Codec Control Messages in the RTP Audio-Visual "Using Codec Control Messages in the RTP Audio-Visual
Profile with Feedback with Layered Codecs", RFC 8082, Profile with Feedback with Layered Codecs", RFC 8082,
DOI 10.17487/RFC8082, March 2017, DOI 10.17487/RFC8082, March 2017,
<https://www.rfc-editor.org/rfc/rfc8082>. <https://www.rfc-editor.org/info/rfc8082>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP: [RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
Session Description Protocol", RFC 8866, Session Description Protocol", RFC 8866,
DOI 10.17487/RFC8866, January 2021, DOI 10.17487/RFC8866, January 2021,
<https://www.rfc-editor.org/rfc/rfc8866>. <https://www.rfc-editor.org/info/rfc8866>.
[RFC9328] Zhao, S., Wenger, S., Sanchez, Y., Wang, Y.-K., and M. M. [RFC9328] Zhao, S., Wenger, S., Sanchez, Y., Wang, Y.-K., and M. M.
Hannuksela, "RTP Payload Format for Versatile Video Coding Hannuksela, "RTP Payload Format for Versatile Video Coding
(VVC)", RFC 9328, DOI 10.17487/RFC9328, December 2022, (VVC)", RFC 9328, DOI 10.17487/RFC9328, December 2022,
<https://www.rfc-editor.org/rfc/rfc9328>. <https://www.rfc-editor.org/info/rfc9328>.
[VSEI] "Versatile supplemental enhancement information messages [VSEI] ITU-T, "Versatile supplemental enhancement information
for coded video bitstreams", 2020, messages for coded video bitstreams", ITU-T
Recommendation H.274, March 2024,
<https://www.itu.int/rec/T-REC-H.274>. <https://www.itu.int/rec/T-REC-H.274>.
13.2. Informative References 12.2. Informative References
[AVC] "ITU-T Recommendation H.264 - Advanced video coding for [AVC] "ITU-T Recommendation H.264 - Advanced video coding for
generic audiovisual services", 2014, generic audiovisual services", 2014,
<https://www.iso.org/standard/66069.html>. <https://www.iso.org/standard/66069.html>.
[HEVC] "High efficiency video coding, ITU-T Recommendation [HEVC] ITU-T, "High efficiency video coding", ITU-T
H.265", 2019, <https://www.itu.int/rec/T-REC-H.265>. Recommendation H.265, September 2023,
<https://www.itu.int/rec/T-REC-H.265>.
[MPEG2S] IS0/IEC, "Information technology - Generic coding ofmoving [MPEG2S] IS0/IEC, "Information technology - Generic coding of
pictures and associated audio information - Part moving pictures and associated audio information - Part 1:
1:Systems, ISO International Standard 13818-1", 2013. Systems", ISO/IEC 13818-1:2013, June 2013.
[RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session [RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session
Announcement Protocol", RFC 2974, DOI 10.17487/RFC2974, Announcement Protocol", RFC 2974, DOI 10.17487/RFC2974,
October 2000, <https://www.rfc-editor.org/rfc/rfc2974>. October 2000, <https://www.rfc-editor.org/info/rfc2974>.
[RFC6184] Wang, Y.-K., Even, R., Kristensen, T., and R. Jesup, "RTP [RFC6184] Wang, Y.-K., Even, R., Kristensen, T., and R. Jesup, "RTP
Payload Format for H.264 Video", RFC 6184, Payload Format for H.264 Video", RFC 6184,
DOI 10.17487/RFC6184, May 2011, DOI 10.17487/RFC6184, May 2011,
<https://www.rfc-editor.org/rfc/rfc6184>. <https://www.rfc-editor.org/info/rfc6184>.
[RFC6190] Wenger, S., Wang, Y.-K., Schierl, T., and A. [RFC6190] Wenger, S., Wang, Y.-K., Schierl, T., and A.
Eleftheriadis, "RTP Payload Format for Scalable Video Eleftheriadis, "RTP Payload Format for Scalable Video
Coding", RFC 6190, DOI 10.17487/RFC6190, May 2011, Coding", RFC 6190, DOI 10.17487/RFC6190, May 2011,
<https://www.rfc-editor.org/rfc/rfc6190>. <https://www.rfc-editor.org/info/rfc6190>.
[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014, Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
<https://www.rfc-editor.org/rfc/rfc7201>. <https://www.rfc-editor.org/info/rfc7201>.
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP [RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, April Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
2014, <https://www.rfc-editor.org/rfc/rfc7202>. 2014, <https://www.rfc-editor.org/info/rfc7202>.
[RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and [RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
for Real-Time Transport Protocol (RTP) Sources", RFC 7656, for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
DOI 10.17487/RFC7656, November 2015, DOI 10.17487/RFC7656, November 2015,
<https://www.rfc-editor.org/rfc/rfc7656>. <https://www.rfc-editor.org/info/rfc7656>.
[RFC7667] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 7667, [RFC7667] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 7667,
DOI 10.17487/RFC7667, November 2015, DOI 10.17487/RFC7667, November 2015,
<https://www.rfc-editor.org/rfc/rfc7667>. <https://www.rfc-editor.org/info/rfc7667>.
[RFC7798] Wang, Y.-K., Sanchez, Y., Schierl, T., Wenger, S., and M. [RFC7798] Wang, Y.-K., Sanchez, Y., Schierl, T., Wenger, S., and M.
M. Hannuksela, "RTP Payload Format for High Efficiency M. Hannuksela, "RTP Payload Format for High Efficiency
Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798,
March 2016, <https://www.rfc-editor.org/rfc/rfc7798>. March 2016, <https://www.rfc-editor.org/info/rfc7798>.
[VVC] "Versatile Video Coding, ITU-T Recommendation H.266", [VVC] ITU-T, "Versatile video coding", ITU-T
2020, <http://www.itu.int/rec/T-REC-H.266>. Recommendation H.266, August 2020,
<http://www.itu.int/rec/T-REC-H.266>.
Acknowledgements
Large parts of this specification share text with the RTP payload
format for VVC [RFC9328]. Roman Chernyak is thanked for his valuable
review comments. We thank the authors of that specification for
their excellent work.
Authors' Addresses Authors' Addresses
Shuai Zhao Shuai Zhao
Intel Intel
2200 Mission College Blvd 2200 Mission College Blvd
Santa Clara, 95054 Santa Clara, California 95054
United States of America United States of America
Email: shuai.zhao@ieee.org Email: shuai.zhao@ieee.org
Stephan Wenger Stephan Wenger
Tencent Tencent
2747 Park Blvd 2747 Park Blvd
Palo Alto, 94588 Palo Alto, California 94588
United States of America United States of America
Email: stewe@stewe.org Email: stewe@stewe.org
Youngkwon Lim Youngkwon Lim
Samsung Electronics Samsung Electronics
6625 Excellence Way 6625 Excellence Way
Plano, 75013 Plano, Texas 75013
United States of America United States of America
Email: yklwhite@gmail.com Email: yklwhite@gmail.com
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