[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Nits]

Versions: 00 draft-zhao-avtcore-rtp-vvc

Network Working Group                                            S. Zhao
Internet-Draft                                                 S. Wenger
Intended status: Standards Track                                 Tencent
Expires: March 6, 2020                                 September 3, 2019


          RTP Payload Format for Versatile Video Coding (VVC)
                     draft-zhao-payload-rtp-vvc-00

Abstract

   This memo describes an RTP payload format for the video coding
   standard ITU-T Recommendation H.266 and ISO/IEC International
   Standard 23090-3, both also known as Versatile Video Coding (VVC) and
   developed by the Joint Video Experts Team (JVET).  The RTP payload
   format allows for packetization of one or more Network Abstraction
   Layer (NAL) units in each RTP packet payload as well as fragmentation
   of a NAL unit into multiple RTP packets.  The payload format has wide
   applicability in videoconferencing, Internet video streaming, and
   high-bitrate entertainment-quality video, among others.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 6, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



Zhao & Wenger             Expires March 6, 2020                 [Page 1]


Internet-Draft         RTP Payload Format for VVC         September 2019


   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Overview of the VVC Codec . . . . . . . . . . . . . . . .   3
       1.1.1.  Coding-Tool Features (informative)  . . . . . . . . .   3
       1.1.2.  Systems and Transport Interfaces  . . . . . . . . . .   6
       1.1.3.  Parallel Processing Support (informative) . . . . . .  10
       1.1.4.  NAL Unit Header . . . . . . . . . . . . . . . . . . .  10
     1.2.  Overview of the Payload Format  . . . . . . . . . . . . .  11
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .  11
   3.  Definitions and Abbreviations . . . . . . . . . . . . . . . .  12
     3.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .  12
       3.1.1.  Definitions from the VVC Specification  . . . . . . .  12
       3.1.2.  Definitions Specific to This Memo . . . . . . . . . .  12
     3.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .  12
   4.  RTP Payload Format  . . . . . . . . . . . . . . . . . . . . .  12
     4.1.  RTP Header Usage  . . . . . . . . . . . . . . . . . . . .  12
     4.2.  Payload Header Usage  . . . . . . . . . . . . . . . . . .  14
     4.3.  Payload Structures  . . . . . . . . . . . . . . . . . . .  15
       4.3.1.  Single NAL Unit Packets . . . . . . . . . . . . . . .  15
       4.3.2.  Aggregation Packets (APs) . . . . . . . . . . . . . .  16
       4.3.3.  Fragmentation Units . . . . . . . . . . . . . . . . .  21
     4.4.  Decoding Order Number . . . . . . . . . . . . . . . . . .  24
   5.  Packetization Rulesumber  . . . . . . . . . . . . . . . . . .  25
   6.  De-packetization Process  . . . . . . . . . . . . . . . . . .  26
   7.  Payload Format Parameters . . . . . . . . . . . . . . . . . .  28
   8.  Use with Feedback Messages  . . . . . . . . . . . . . . . . .  28
     8.1.  Picture Loss Indication (PLI) . . . . . . . . . . . . . .  28
     8.2.  Slice Loss Indication (SLI) . . . . . . . . . . . . . . .  29
     8.3.  Reference Picture Selection Indication (RPSI) . . . . . .  29
     8.4.  Full Intra Request (FIR)  . . . . . . . . . . . . . . . .  29
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
   10. Congestion Control  . . . . . . . . . . . . . . . . . . . . .  31
   11. IANA Considertaions . . . . . . . . . . . . . . . . . . . . .  32
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  32
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  32
     13.2.  Informative References . . . . . . . . . . . . . . . . .  34
   Appendix A.  Change History . . . . . . . . . . . . . . . . . . .  35
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  35






Zhao & Wenger             Expires March 6, 2020                 [Page 2]


Internet-Draft         RTP Payload Format for VVC         September 2019


1.  Introduction

   The VVC specification, formally published as both ITU-T
   Recommendation H.266 and ISO/IEC International Standard 23090-23
   [ISO23090-3], is planned for ratification in mid 2020.  A draft
   that's currently in the approval process of ISO/IEC can be found as
   [VVC].  H.266 is reported to provide significant coding efficiency
   gains over H.265 [H.265] and earlier video codec formats.

   This memo describes an RTP payload format for [VVC].  It shares its
   basic design with the NAL unit-based RTP payload formats of
   [RFC7798], [RFC6184] and [RFC6190] .  With respect to design
   philosophy, security, congestion control, and overall implementation
   complexity, it has similar properties to those earlier payload format
   specifications.  This is a conscious choice, as at least RFC 6184 is
   widely deployed and generally known in the relevant implementer
   communities.  Certain mechanisms known from RFC 6190 were
   incorporated as [VVC] version 1 supports all temporal, spatial, and
   SNR scalability.

1.1.  Overview of the VVC Codec

   [VVC] and H.265 share a similar hybrid video codec design.  In this
   memo, we provide a very brief overview of those features of [VVC]
   that are, in some form, addressed by the payload format specified
   herein.  Implementers have to read, understand, and apply the ITU-
   T/ISO/IEC specifications pertaining to [VVC] to arrive at
   interoperable, well-performing implementations.

   Conceptually, both [VVC] and HEVC include a Video Coding Layer (VCL),
   which is often used to refer to the coding-tool features, and a
   Network Abstraction Layer (NAL), which is often used to refer to the
   systems and transport interface aspects of the codecs.

1.1.1.  Coding-Tool Features (informative)

   Coding tool features are described below with occasional reference to
   the coding tool set of HEVC, which is believed to be well known in
   the community.

   Similar to earlier hybrid-video-coding-based standards, including
   HEVC, the following basic video coding design is employed by [VVC].
   A prediction signal is first formed by either intra- or motion-
   compensated prediction, and the residual (the difference between the
   original and the prediction) is then coded.  The gains in coding
   efficiency are achieved by redesigning and improving almost all parts
   of the codec over earlier designs.  In addition, VVC includes several
   tools to make the implementation on parallel architectures easier.



Zhao & Wenger             Expires March 6, 2020                 [Page 3]


Internet-Draft         RTP Payload Format for VVC         September 2019


   Finally, VVC includes temporal, spatial, and SNR scalability as well
   as multiview coding support.

   Coding blocks and transform structure

   Among major coding-tool differences between HEVC and [VVC], one of
   the important improvements is the more flexible coding tree structure
   in VVC, i.e., multi-type tree.  In addition to quadtree, binary and
   ternary trees are also supported, which contributes significant
   improvement in coding efficiency.  Moreover, the maximum size of
   Coding Tree Unit (CTU) is increased from 64x64 to 128x128.  To
   improve the coding efficiency of chroma signal, luma chroma separated
   trees at CTU level may be employed for intra-slices.  As to
   transform, the square transforms in HEVC are extended to non-square
   transforms for rectangular blocks resulted from binary and ternary
   tree splits.  Besides, [VVC] supports multiple transform sets (MTS),
   including DCT-2, DST-7, and DCT-8 as well as the non-separable
   secondary transform.  The transforms used in [VVC] can have different
   sizes with support for larger transform sizes.  For DCT-2, the
   transform sizes range from 2x2 to 64x64, and for DST-7 and DCT-8, the
   transform sizes range from 4x4 to 32x32.  In addition, [VVC] also
   support sub-block transform for both intra and inter coded blocks.
   For intra coded blocks, intra sub-partitioning (ISP) may be used to
   allow sub-block based intra prediction and transform.  For inter
   blocks, sub-block transform may be used assuming that only a part of
   an inter-block has non-zero transform coefficients.

   Entropy coding

   Similar to HEVC , [VVC] uses a single entropy-coding engine, which is
   based on Context Adaptive Binary Arithmetic Coding (CABAC) [CABAC],
   but with the support of multi-window sizes.  The window sizes can be
   initialized differently for different context models.  Due to such a
   design, it has more efficient adaptation speed and better coding
   efficiency.  A joint chroma residual coding scheme is applied to
   further exploit the correlation between the residuals of two colour
   components.  In [VVC], different residual coding schemes are applied
   for regular transform coefficients and residual samples generated
   using transform-skip mode.

   In-loop filtering

   [VVC] has more feature supports in loop filters than HEVC.  The
   deblocking filter in [VVC] is similar to HEVC but operates at a
   smaller grid.  After deblocking and sample adaptive offset (SAO), an
   adaptive loop filter (ALF) may be used.  As a Wiener filter, ALF
   reduces distortion of decoded pictures.  Besides, [VVC] introduces a
   new module before deblocking called luma mapping with chroma scaling



Zhao & Wenger             Expires March 6, 2020                 [Page 4]


Internet-Draft         RTP Payload Format for VVC         September 2019


   to fully utilize the dynamic range of signal so that rate-distortion
   performance of both SDR and HDR content is improved.

   Motion prediction and coding

   Compared to HEVC, [VVC] introduces several improvements in this area.
   First, there is the Adaptive motion vector resolution (AMVR), which
   can save bit cost for motion vectors by adaptively signaling motion
   vector resolution.  Then the Affine motion compensation is included
   to capture complicated motion like zooming and rotation.  Meanwhile,
   prediction refinement with the optical flow with affine mode (PROF)
   is further deployed to mimic affine motion at the pixel level.
   Thirdly the decoder side motion vector refinement (DMVR) is a method
   to derive MV vector at decoder side so that fewer bits may be spent
   on motion vectors.  Bi-directional optical flow (BDOF) is a similar
   method to DMVR but at 4x4 sub-block level.  Another difference is
   that DMVR is based on block matching while BDOF derives MVs with
   equations.  Furthermore, merge with motion vector difference (MMVD)
   is a special mode, which further signals a limited set of motion
   vector differences on top of merge mode.  In addition to MMVD, there
   are another three types of special merge modes, i.e., sub-block
   merge, triangle, and combined intra-/inter- prediction (CIIP).  Sub-
   block merge list includes one candidate of sub-block temporal motion
   vector prediction (SbTMVP) and up to four candidates of affine motion
   vectors.  Triangle is based on triangular block motion compensation.
   CIIP combines intra- and inter- predictions with weighting.
   Moreover, weighting in bi-prediction has more flexibility then HEVC.
   Adaptive weighting may be employed with a block-level tool called bi-
   prediction with CU based weighting (BCW).

   Intra prediction and intra-coding

   To capture the diversified local image texture directions with finer
   granularity, [VVC] supports 65 angular directions instead of 33
   directions in HEVC.  The intra mode coding is based on a 6 most
   probable mode scheme, and the 6 most probable modes are derived using
   the neighboring intra prediction directions.  In addition, to deal
   with the different distributions of intra prediction angles for
   different block aspect ratios, a wide-angle intra prediction (WAIP)
   scheme is applied in [VVC] by including intra prediction angles
   beyond those present in HEVC.  Unlike HEVC which only allows using
   the most adjacent line of reference samples for intra prediction,
   [VVC] also allows using two further reference lines, as known as
   multi-reference-line (MRL) intra prediction.  The additional
   reference lines can be only used for 6 most probable intra prediction
   modes.  To capture the strong correlation between different colour
   components, in [VVC], a cross-component linear mode (CCLM) is
   utilized which assumes a linear relationship between the luma sample



Zhao & Wenger             Expires March 6, 2020                 [Page 5]


Internet-Draft         RTP Payload Format for VVC         September 2019


   values and their associated chroma samples.  For intra prediction,
   [VVC] also applies a position-dependent prediction combination (PDPC)
   for refining the prediction samples closer to the intra prediction
   block boundary.  Matrix-based intra-prediction (MIP) modes are also
   used in [VVC] which generates an up to 8x8 intra prediction block
   using a weighted sum of downsampled neighboring reference samples,
   and the weightings are hardcoded constants.

   Other coding-tool feature

   [VVC] introduces dependent quantization (DQ) to reduce quantization
   error by state-based switching between two quantizers.

1.1.2.  Systems and Transport Interfaces

   [VVC] inherits the basic systems and transport interfaces designs
   from HEVC and H.264.  These include the NAL-unit-based syntax
   structure, the hierarchical syntax and data unit structure, the
   Supplemental Enhancement Information (SEI) message mechanism, and the
   video buffering model based on the Hypothetical Reference Decoder
   (HRD).  The scalability features of [VVC] are conceptually similar to
   the scalable variant of HEVC known as SHVC.  The hierarchical syntax
   and data unit structure consists of parameter sets at various levels
   (decoder, sequence (including layers), sequence (per layer),
   picture), slice-level header parameters, and lower-level parameters.

   Below described are a number of key components that influenced the
   Network Abstraction Layer design of VVC as well as this memo.

   Decoder parameter set

   The Decoder parameter set includes parameters that stay constant for
   the lifetime of a Video Bitstream, which in IETF terms can translate
   to the lifetime of a session.  Decoder parameter sets can include
   profile, level, and sub-profile information to determine a maximum
   complexity interop point that is guaranteed to be never exceeded,
   even if splicing of video sequences occurs within a session.  It
   further optionally includes constraint flags, which indicate that the
   video bitstream will be constraint of the use of certain features as
   indicated by the values of those flags.  With this, a bitstream can
   be labelled as not using certain tools, which allows among other
   things for resource allocation in a decoder implementation.  As all
   parameter sets, also the decoder parameter set is required to be
   present when first referenced, and it is necessarily referenced by
   the very first picture in a video sequence, implying that it has to
   be sent among the first NAL units in the bitstream (see section xxx
   below).  While multiple DPSs can be in the bitstream, the value of




Zhao & Wenger             Expires March 6, 2020                 [Page 6]


Internet-Draft         RTP Payload Format for VVC         September 2019


   the syntax elements therein cannot be inconsistent when being
   referenced.

   Video parameter set

   The Video Parameter Set (VPS) includes decoding dependency or
   information for reference picture set construction of enhancement
   layers.  The VPS provides a "big picture" of a scalable sequence,
   including what types of operation points are provided, the profile,
   tier, and level of the operation points, and some other high-level
   properties of the bitstream that can be used as the basis for session
   negotiation and content selection, etc. (see Section xxx).

   Sequence parameter set

   The Sequence Parameter Set (SPS) contains syntax elements pertaining
   to a coded video sequence (CVS), which is a group of pictures,
   starting with a random access point, and followed by pictures that
   may depend on each other and the random access point picture.  In
   MPGEG-2, the equivalent of a CVS was a Group of Pictures (GOP), which
   normally started with an I frame and was followed by P and B frames.
   While more complex in its options of random access points, [VVC]
   retains this basic concept.  In many TV-like applications, a CVS
   contains a few hundred milliseconds to a few seconds of video.  In
   video conferencing (without switching MCUs involved), a CVS can be as
   long in duration as the whole session.

   Picture and Adaptation parameter set

   The Picture Parameter Set and the Adaptation Parameter Set (PPS and
   APS, respectively) carry information pertaining to a single picture.
   The PPS contains information that is likely to stay constant from
   picture to picture-at least for pictures for a certain type-whereas
   the APS contains information, such as adaptive loop filter
   coefficients, that are likely to change from picture to picture.

   Profile, tier, and level

   The profile, tier, and level syntax structure can be included in all
   DPS, VPS, and SPS.  Somewhat oversimplified, they can be viewed to
   provide information about maximum bitstream complexity in the
   dimensions of tools used (profile), sample count (level), and maximum
   bitrate (tier).  Level and tier are onion shaped, in that a decoder
   that can decode a certain level or tier can also decode lower levels
   or tiers.  Profiles are not necessarily onion shaped and do not
   necessarily form a hierarchy.  Therefore, the profile_tier_level
   structure in the video bitstream contains a bitmask which allows an
   encoder to mark a bitstream to be compatible with multiple profiles.



Zhao & Wenger             Expires March 6, 2020                 [Page 7]


Internet-Draft         RTP Payload Format for VVC         September 2019


   Sub-Profiles

   Within the [VVC] specification, a sub-profile is simply a 32 bit
   number coded according to ITU-T Rec. T.35, that does not carry a
   semantic.  It is carried in the profile_tier_level structure and
   hence (potentially) present in the DPS, VPS, and SPS.  External
   registration bodies can register a T.35 codepoint with ITU-T
   registration authorities and associate with their registration a
   description of bitstream complexity restrictions beyond the profiles
   defined by ITU-T and ISO/IEC.  This would allow encoder manufacturers
   to label the bitstreams generated by their encoder as complying with
   such sub-profile.  It is expected that upstream standardization
   organizations (such as: DVB and ATSC), as well as large walled-garden
   video services will take advantage of this labelling system.  In
   contrast to "normal" profiles, it is expected that sub-profiles may
   indicate encoder choices traditionally left open in the (decoder-
   centric) video coding specs, such as GOP structures, minimum/maximum
   QP values, and the mandatory use of certain tools or SEI messages.

   Constraint Flags

   The profile_tier_level structure optionally carries a considerable
   number of constraint flags, which an encoder can use to indicate to a
   decoder that it will not use a certain tool or technology.  They were
   included in reaction to a perceived market need for labelling a
   bitstream as not exercising a certain tool that has become
   commercially unviable.

   Temporal scalability support

   Edt. note: this section may need adjustment as JVET work on bitstream
   extraction is in progress.

   [VVC] includes support of temporal scalability, by inclusion of the
   signaling of TemporalId in the NAL unit header, the restriction that
   pictures of a particular temporal sub-layer cannot be used for inter
   prediction reference by pictures of a lower temporal sub-layer, the
   sub-bitstream extraction process, and the requirement that each sub-
   bitstream extraction output be a conforming bitstream.  Media-Aware
   Network Elements (MANEs) can utilize the TemporalId in the NAL unit
   header for stream adaptation purposes based on temporal scalability.

   Spatial, SNR, View Scalability

   [VVC] includes support for spatial, SNR, and View scalability.
   Scalable video coding is widely considered to have technical benefits
   and enrich services for various video applications.  Until recently,
   however, the functionality has not been included in the main profiles



Zhao & Wenger             Expires March 6, 2020                 [Page 8]


Internet-Draft         RTP Payload Format for VVC         September 2019


   of video codecs and not wide deployed due to additional costs.  In
   VVC, however, all those forms of scalability are supported natively
   through the signaling of the layer_id in the NAL unit header, the VPS
   which associates layers with given layer_ids to each other, reference
   picture selection, reference picture resampling for spatial
   scalability, and a number of other mechanisms not relevant for this
   memo.  Scalability support can be implemented in a single decoding
   "loop" and is widely considered a comparatively lightweight
   operation.

      Spatial Scalability

      With the existence of Reference Picture Resampling, likely in the
      "main" profile of VVC, the additional burden for scalability
      support is just a minor modification of the high-level syntax
      (HLS).  In technical aspects, the inter-layer prediction is
      employed in a scalable system to improve the coding efficiency of
      the enhancement layers.  In addition to the spatial and temporal
      motion-compensated predictions that are available in a single-
      layer codec, the inter-layer prediction in [VVC] uses the
      resampled video data of the reconstructed reference picture from a
      reference layer to predict the current enhancement layer.  Then,
      the resampling process for inter-layer prediction is performed at
      the block-level, by modifying the existing interpolation process
      for motion compensation.  It means that no additional resampling
      process is needed to support scalability.

      SNR Scalability>

      SNR scalability is similar to Spatial Scalability except that the
      resampling factors are 1:1--in other words, tehre is no change in
      resolution, but there is inter-layer prediction.

      View Scalability>

      Placeholder

   SEI Messages

   Supplementary Enhancement Information (SEI) messages are codepoints
   in the bitstream that do not influence the decoding process as
   specified in the [VVC] spec, but address issues of representation/
   rendering of the decoded bitstream, label the bitstream for certain
   applications, among other, similar tasks.  The overall concept of SEI
   messages and many of the messages themselves has been inherited from
   the H.264 and HEVC specs.  In the [VVC] environment, some of the SEI
   messages considered to be generally useful also in other video coding
   technologies have been moved out of the main specification info a



Zhao & Wenger             Expires March 6, 2020                 [Page 9]


Internet-Draft         RTP Payload Format for VVC         September 2019


   companion document (TO DO: add reference once ITU designation is
   known).

1.1.3.  Parallel Processing Support (informative)

   Compared to HEVC [RFC7798], the [VVC] design to support
   parallelization offers numerous improvements.  Some of those
   improvements are still undergoing changes in JVET.  Information, to
   the extent relevant for this memo, will be added in future versions
   of this memo as the standardization in JVET progresses and the
   technology stabilizes.

1.1.4.  NAL Unit Header

   [VVC] maintains the NAL unit concept of HEVC with modifications.  VVC
   uses a two-byte NAL unit header, as shown in Figure 1.  The payload
   of a NAL unit refers to the NAL unit excluding the NAL unit header.

                          +---------------+---------------+
                          |0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
                          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                          |F|Z| LayerID   |  Type   | TID |
                          +---------------+---------------+

                The Structure of the [VVC] NAL Unit Header.

                                 Figure 1

   The semantics of the fields in the NAL unit header are as specified
   in [VVC] and described briefly below for convenience.  In addition to
   the name and size of each field, the corresponding syntax element
   name in [VVC] is also provided.

   F: 1 bit

      forbidden_zero_bit.  Required to be zero in [VVC].  Note that the
      inclusion of this bit in the NAL unit header was to enable
      transport of [VVC] video over MPEG-2 transport systems (avoidance
      of start code emulations) [MPEG2S].  In the context of this memo
      the value 1 may be used to indicate a syntax violation, e.g., for
      a NAL unit resulted from aggregating a number of fragmented units
      of a NAL unit but missing the last fragment, as described in
      Section TBD.

   Z: 1 bit

      nuh_reserved_zero_bit.  Required to be zero in [VVC], and reserved
      for future extensions by ITU-T and ISO/IEC.  This memo does not



Zhao & Wenger             Expires March 6, 2020                [Page 10]


Internet-Draft         RTP Payload Format for VVC         September 2019


      overload the "Z" bit for local extensions, as a) overloading the
      "F" bit is sufficient and b) to preserve the usefulness of this
      memo to possible future versions of [VVC].

   LayerId: 6 bits

      nuh_layer_id.  Identifies the layer a NAL unit belongs to, wherein
      a layer may be, e.g., a spatial scalable layer, a quality scalable
      layer .

   Type: 6 bits

      nal_unit_type.  This field specifies the NAL unit type as defined
      in Table 7-1 of [VVC].  For a reference of all currently defined
      NAL unit types and their semantics, please refer to
      Section 7.4.2.2 in [VVC].

   TID: 3 bits

      nuh_temporal_id_plus1.  This field specifies the temporal
      identifier of the NAL unit plus 1.  The value of TemporalId is
      equal to TID minus 1.  A TID value of 0 is illegal to ensure that
      there is at least one bit in the NAL unit header equal to 1, so to
      enable independent considerations of start code emulations in the
      NAL unit header and in the NAL unit payload data.

1.2.  Overview of the Payload Format

   This payload format defines the following processes required for
   transport of [VVC] coded data over RTP [RFC3550]:

   o  Usage of RTP header with this payload format

   o  Packetization of [VVC] coded NAL units into RTP packets using
      three types of payload structures: a single NAL unit packet,
      aggregation packet, and fragment unit

   o  Transmission of HEVC NAL units of the same bitstream within a
      single RTP stream.

   o  Media type parameters to be used with the Session Description
      Protocol (SDP) [RFC4566]

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14 [RFC2119].  In



Zhao & Wenger             Expires March 6, 2020                [Page 11]


Internet-Draft         RTP Payload Format for VVC         September 2019


   this document, the above key words will convey that interpretation
   only when in ALL CAPS.  Lowercase uses of these words are not to be
   interpreted as carrying the significance described in RFC 2119.  This
   specification uses the notion of setting and clearing a bit when bit
   fields are handled.  Setting a bit is the same as assigning that bit
   the value of 1 (On).  Clearing a bit is the same as assigning that
   bit the value of 0 (Off).

3.  Definitions and Abbreviations

3.1.  Definitions

   This document uses the terms and definitions of [VVC].  Section 3.1.1
   lists relevant definitions from [VVC] for convenience.  Section 3.1.2
   provides definitions specific to this memo.

3.1.1.  Definitions from the VVC Specification

   Placeholder

3.1.2.  Definitions Specific to This Memo

   Placeholder

3.2.  Abbreviations

   Placeholder

4.  RTP Payload Format

4.1.  RTP Header Usage

   The format of the RTP header is specified in [RFC3550] (reprinted as
   Figure 2 for convenience).  This payload format uses the fields of
   the header in a manner consistent with that specification.

   The RTP payload (and the settings for some RTP header bits) for
   aggregation packets and fragmentation units are specified in Sections
   4.4.2 and 4.4.3, respectively.












Zhao & Wenger             Expires March 6, 2020                [Page 12]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |V=2|P|X|  CC   |M|     PT      |       sequence number         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           timestamp                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           synchronization source (SSRC) identifier            |
   +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
   |            contributing source (CSRC) identifiers             |
   |                             ....                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     RTP Header According to [RFC3550]

                                 Figure 2

   The RTP header information to be set according to this RTP payload
   format is set as follows:

   Marker bit (M): 1 bit

      Set for the last packet of the access unit, carried in the current
      RTP stream.  This is in line with the normal use of the M bit in
      video formats to allow an efficient playout buffer handling.

         The informative note below needs updating once the NAL unit
         type table is stable in the [VVC] spec

         Informative note: The content of a NAL unit does not tell
         whether or not the NAL unit is the last NAL unit, in decoding
         order, of an access unit.  An RTP sender implementation may
         obtain this information from the video encoder.  If, however,
         the implementation cannot obtain this information directly from
         the encoder, e.g., when the bitstream was pre-encoded, and also
         there is no timestamp allocated for each NAL unit, then the
         sender implementation can inspect subsequent NAL units in
         decoding order to determine whether or not the NAL unit is the
         last NAL unit of an access unit as follows.  A NAL unit is
         determined to be the last NAL unit of an access unit if it is
         the last NAL unit of the bitstream.  A NAL unit naluX is also
         determined to be the last NAL unit of an access unit if both
         the following conditions are true: 1) the next VCL NAL unit
         naluY in decoding order has the high-order bit of the first
         byte after its NAL unit header equal to 1, and 2) all NAL units
         between naluX and naluY, when present, have nal_unit_type in
         the range of 32 to 35, inclusive, equal to 39, or in the ranges
         of 41 to 44, inclusive, or 48 to 55, inclusive.



Zhao & Wenger             Expires March 6, 2020                [Page 13]


Internet-Draft         RTP Payload Format for VVC         September 2019


   Payload Type (PT): 7 bits

      The assignment of an RTP payload type for this new packet format
      is outside the scope of this document and will not be specified
      here.  The assignment of a payload type has to be performed either
      through the profile used or in a dynamic way.



   Sequence Number (SN): 16 bits

      Set and used in accordance with [RFC3550] .

   Timestamp: 32 bits

      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
      properties of its own (e.g., parameter set and SEI NAL units), the
      RTP timestamp MUST be set to the RTP timestamp of the coded
      picture of the access unit in which the NAL unit (according to
      Section xxx of [VVC]) is included.  Receivers MUST use the RTP
      timestamp for the display process, even when the bitstream
      contains picture timing SEI messages or decoding unit information
      SEI messages as specified in [VVC].  However, this does not mean
      that picture timing SEI messages in the bitstream should be
      discarded, as picture timing SEI messages may contain frame-field
      information that is important in appropriately rendering
      interlaced video.

   Synchronization source (SSRC): 32 bits

      Used to identify the source of the RTP packets.  When using SRST,
      by definition a single SSRC is used for all parts of a single
      bitstream.

4.2.  Payload Header Usage

   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
   fields (F, Z, LayerId, Type, and TID) as the NAL unit header as shown
   in Section 1.1.4, irrespective of the type of the payload structure.

   The TID value indicates (among other things) the relative importance
   of an RTP packet, for example, because NAL units belonging to higher
   temporal sub-layers are not used for the decoding of lower temporal
   sub-layers.  A lower value of TID indicates a higher importance.
   More-important NAL units MAY be better protected against transmission
   losses than less-important NAL units.



Zhao & Wenger             Expires March 6, 2020                [Page 14]


Internet-Draft         RTP Payload Format for VVC         September 2019


   For Discussion: quite possibly something similar can be said for the
   Layer_id in layered coding, but perhaps not in multiview coding.
   (The relevant part of the spec is relatively new, therefore the soft
   language).  However, for serious layer pruning, interpretation of the
   VPS is required.  We can add language about the need for starteful
   interpretation of LayerID vis-a-vis stateless interpretation of TID
   later.

4.3.  Payload Structures

   Four different types of RTP packet payload structures are specified.
   A receiver can identify the type of an RTP packet payload through the
   Type field in the payload header.

   The four different payload structures are as follows:

   o  Single NAL unit packet: Contains a single NAL unit in the payload,
      and the NAL unit header of the NAL unit also serves as the payload
      header.  This payload structure is specified in Section 4.4.1.

   o  Aggregation Packet (AP): Contains more than one NAL unit within
      one access unit.  This payload structure is specified in
      Section 4.4.2.

   o  Fragmentation Unit (FU): Contains a subset of a single NAL unit.
      This payload structure is specified in Section 4.4.3.

4.3.1.  Single NAL Unit Packets

   A single NAL unit packet contains exactly one NAL unit, and consists
   of a payload header (denoted as PayloadHdr), a conditional 16-bit
   DONL field (in network 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.

















Zhao & Wenger             Expires March 6, 2020                [Page 15]


Internet-Draft         RTP Payload Format for VVC         September 2019


     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |           PayloadHdr          |      DONL (conditional)       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |                  NAL unit payload data                        |
    |                                                               |
    |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               :...OPTIONAL RTP padding        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                 The Structure of a Single NAL Unit Packet

                                 Figure 3

   The DONL field, when present, specifies the value of the 16 least
   significant bits of the decoding order number of the contained NAL
   unit.  If sprop-max-don-diff is greater than 0 for any of the RTP
   streams, 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
   field.  Otherwise (sprop-max-don-diff is equal to 0 for all the RTP
   streams), the DONL field MUST NOT be present.

4.3.2.  Aggregation Packets (APs)

   Aggregation Packets (APs) are introduced to enable the reduction of
   packetization overhead for small NAL units, such as most of the non-
   VCL NAL units, which are often only a few octets in size.

   An AP aggregates NAL units within one access unit.  Each NAL unit to
   be carried in an AP is encapsulated in an aggregation unit.  NAL
   units aggregated in one AP are in NAL unit decoding order.

   An AP consists of a payload header (denoted as PayloadHdr) followed
   by two or more aggregation units, as shown in Figure 4.














Zhao & Wenger             Expires March 6, 2020                [Page 16]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    PayloadHdr (Type=48)       |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   |                                                               |
   |             two or more aggregation units                     |
   |                                                               |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               :...OPTIONAL RTP padding        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  The Structure of an Aggregation Packet

                                 Figure 4

   The fields in the payload header are set as follows.  The F 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 be equal
   to 48.

   NOTE: double check #48 against post-geneva [VVC] spec

   The value of LayerId MUST be equal to the lowest value of LayerId of
   all the aggregated NAL units.  The value of TID MUST be the lowest
   value of TID of all the aggregated NAL units.

      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
      may contain non-VCL NAL units for which the TID value in the NAL
      unit header may be different than the TID value of the VCL NAL
      units in the same AP.

   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
   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 MTU size
   so to avoid IP layer fragmentation.  An AP MUST NOT contain FUs
   specified in Section 4.4.3.  APs MUST NOT be nested; i.e., an AP must
   not contain another AP.

   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
   information (in network byte order) that indicates the size of the
   NAL unit in bytes (excluding these two octets, but including the NAL
   unit header), followed by the NAL unit itself, including its NAL unit
   header, as shown in Figure 5.



Zhao & Wenger             Expires March 6, 2020                [Page 17]


Internet-Draft         RTP Payload Format for VVC         September 2019


      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |               :       DONL (conditional)      |   NALU size   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   NALU size   |                                               |
     +-+-+-+-+-+-+-+-+         NAL unit                              |
     |                                                               |
     |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                               :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Structure of the First Aggregation Unit in an AP

                                 Figure 5

   The DONL field, when present, specifies the value of the 16 least
   significant bits of the decoding order number of the aggregated NAL
   unit.

   If sprop-max-don-diff is greater than 0 for any of the RTP streams,
   the DONL field MUST be present in an aggregation unit that is the
   first aggregation unit in an AP, and the variable DON for the
   aggregated NAL unit is derived as equal to the value of the DONL
   field.  Otherwise (sprop-max-don-diff is equal to 0 for all the RTP
   streams), the DONL field MUST NOT be present in an aggregation unit
   that is the first aggregation unit in an AP.

   An aggregation unit that is not the first aggregation unit in an AP
   consists of a conditional 8-bit DOND field followed by a 16-bit
   unsigned size information (in network byte order) that indicates the
   size of the NAL unit in bytes (excluding these two octets, but
   including the NAL unit header), followed by the NAL unit itself,
   including its NAL unit header, as shown in Figure 6.
















Zhao & Wenger             Expires March 6, 2020                [Page 18]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               : DOND (cond)   |          NALU size            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                       NAL unit                                |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               :
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



        The Structure of an Aggregation Unit That Is Not the First
                         Aggregation Unit in an AP

                                 Figure 6

   When present, the DOND field plus 1 specifies the difference between
   the decoding order number values of the current aggregated NAL unit
   and the preceding aggregated NAL unit in the same AP.

   If sprop-max-don-diff is greater than 0 for any of the RTP streams,
   the DOND field MUST be present in an aggregation unit that is not the
   first aggregation unit in an AP, and the variable DON for the
   aggregated NAL unit is derived as equal to the DON of the preceding
   aggregated NAL unit in the same AP plus the value of the DOND field
   plus 1 modulo 65536.  Otherwise (sprop-max-don-diff is equal to 0 for
   all the RTP streams), the DOND field MUST NOT be present in an
   aggregation unit that is not the first aggregation unit in an AP, and
   in this case the transmission order and decoding order of NAL units
   carried in the AP are the same as the order the NAL units appear in
   the AP.

   Figure 7 presents an example of an AP that contains two aggregation
   units, labeled as 1 and 2 in the figure, without the DONL and DOND
   fields being present.














Zhao & Wenger             Expires March 6, 2020                [Page 19]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          RTP Header                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   PayloadHdr (Type=XX)        |         NALU 1 Size           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          NALU 1 HDR           |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+         NALU 1 Data           |
   |                   . . .                                       |
   |                                                               |
   +               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  . . .        | NALU 2 Size                   | NALU 2 HDR    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | NALU 2 HDR    |                                               |
   +-+-+-+-+-+-+-+-+              NALU 2 Data                      |
   |                   . . .                                       |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               :...OPTIONAL RTP padding        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



    An Example of an AP Packet Containing Two Aggregation Units without
                         the DONL and DOND Fields

                                 Figure 7

   Figure 8 presents an example of an AP that contains two aggregation
   units, labeled as 1 and 2 in the figure, with the DONL and DOND
   fields being present.




















Zhao & Wenger             Expires March 6, 2020                [Page 20]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          RTP Header                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   PayloadHdr (Type=XX)        |        NALU 1 DONL            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          NALU 1 Size          |            NALU 1 HDR         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                 NALU 1 Data   . . .                           |
   |                                                               |
   +     . . .     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |               |  NALU 2 DOND  |          NALU 2 Size          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          NALU 2 HDR           |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          NALU 2 Data          |
   |                                                               |
   |        . . .                  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               :...OPTIONAL RTP padding        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    An Example of an AP Containing Two Aggregation Units with the DONL
                              and DOND Fields

                                 Figure 8

4.3.3.  Fragmentation Units

   Fragmentation Units (FUs) are introduced to enable fragmenting a
   single NAL unit into multiple RTP packets, possibly without
   cooperation or knowledge of the HEVC [RFC7798] encoder.  A fragment
   of a NAL unit consists of an integer number of consecutive octets of
   that NAL unit.  Fragments of the same NAL unit MUST be sent in
   consecutive order with ascending RTP sequence numbers (with no other
   RTP packets within the same RTP stream being sent between the first
   and last fragment).

   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
   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-
   time of the fragmented NAL unit.

   An FU consists of a payload header (denoted as PayloadHdr), an FU
   header of one octet, a conditional 16-bit DONL field (in network byte
   order), and an FU payload, as shown in Figure 9.



Zhao & Wenger             Expires March 6, 2020                [Page 21]


Internet-Draft         RTP Payload Format for VVC         September 2019


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    PayloadHdr (Type=XX)       |   FU header   | DONL (cond)   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
   | DONL (cond)   |                                               |
   |-+-+-+-+-+-+-+-+                                               |
   |                         FU payload                            |
   |                                                               |
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               :...OPTIONAL RTP padding        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Structure of an FU

                                 Figure 9

   The fields in the payload header are set as follows.  The Type field
   MUST be equal to XX.  The fields F, LayerId, and TID MUST be equal to
   the fields F, LayerId, and TID, respectively, of the fragmented NAL
   unit.

   The FU header consists of an S bit, an E bit, and a 6-bit FuType
   field, as shown in Figure 10.

            +---------------+
            |0|1|2|3|4|5|6|7|
            +-+-+-+-+-+-+-+-+
            |S|E|  FuType   |
            +---------------+


   The Structure of FU Header

                                 Figure 10

   The semantics of the FU header fields are as follows:

   S: 1 bit

      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
      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
      bit MUST be set to 0.

   E: 1 bit



Zhao & Wenger             Expires March 6, 2020                [Page 22]


Internet-Draft         RTP Payload Format for VVC         September 2019


      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
      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.

   FuType: 6 bits

      The field FuType MUST be equal to the field Type of the fragmented
      NAL unit.

   The DONL field, when present, specifies the value of the 16 least
   significant bits of the decoding order number of the fragmented NAL
   unit.

   If sprop-max-don-diff is greater than 0 for any of the RTP streams,
   and the S bit is equal to 1, 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 field.  Otherwise (sprop-max-don-diff
   is equal to 0 for all the RTP streams, or 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.,
   the Start bit and End bit must not both be set to 1 in the same FU
   header.

   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
   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
   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
   rather the information of the NAL unit header of the fragmented NAL
   unit is conveyed in F, LayerId, and TID fields of the FU payload
   headers of the FUs and the FuType field of the FU header of the FUs.
   An FU payload MUST NOT be empty.

   If an FU is lost, the receiver SHOULD discard all following
   fragmentation units in transmission order corresponding to the same
   fragmented NAL unit, unless the decoder in the receiver is known to
   be prepared to gracefully handle incomplete NAL units.

   A receiver in an endpoint or in a MANE MAY aggregate the first n-1
   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
   forbidden_zero_bit of the NAL unit MUST be set to 1 to indicate a
   syntax violation.





Zhao & Wenger             Expires March 6, 2020                [Page 23]


Internet-Draft         RTP Payload Format for VVC         September 2019


4.4.  Decoding Order Number

   For each NAL unit, the variable AbsDon is derived, representing the
   decoding order number that is indicative of the NAL unit decoding
   order.

   Let NAL unit n be the n-th NAL unit in transmission order within an
   RTP stream.

   If sprop-max-don-diff is equal to 0 for all the RTP streams carrying
   the HEVC bitstream, AbsDon[n], the value of AbsDon for NAL unit n, is
   derived as equal to n.

   Otherwise (sprop-max-don-diff is greater than 0 for any of the RTP
   streams), AbsDon[n] is derived as follows, where DON[n] is the value
   of the variable DON for NAL unit n:

   o  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].

   o  Otherwise (n is greater than 0), the following applies for
      derivation of AbsDon[n]:



      If DON[n] == DON[n-1],
         AbsDon[n] = AbsDon[n-1]

      If (DON[n] > DON[n-1] and DON[n] - DON[n-1] < 32768),
         AbsDon[n] = AbsDon[n-1] + DON[n] - DON[n-1]

      If (DON[n] < DON[n-1] and DON[n-1] - DON[n] >= 32768),
         AbsDon[n] = AbsDon[n-1] + 65536 - DON[n-1] + DON[n]

      If (DON[n] > DON[n-1] and DON[n] - DON[n-1] >= 32768),
         AbsDon[n] = AbsDon[n-1] - (DON[n-1] + 65536 -
         DON[n])

      If (DON[n] < DON[n-1] and DON[n-1] - DON[n] < 32768),
         AbsDon[n] = AbsDon[n-1] - (DON[n-1] - DON[n])

   For any two NAL units m and n, the following applies:

   o  AbsDon[n] greater than AbsDon[m] indicates that NAL unit n follows
      NAL unit m in NAL unit decoding order.

   o  When AbsDon[n] is equal to AbsDon[m], the NAL unit decoding order
      of the two NAL units can be in either order.



Zhao & Wenger             Expires March 6, 2020                [Page 24]


Internet-Draft         RTP Payload Format for VVC         September 2019


   o  AbsDon[n] less than AbsDon[m] indicates that NAL unit n precedes
      NAL unit m in decoding order.

         Informative note: When two consecutive NAL units in the NAL
         unit decoding order have different values of AbsDon, the
         absolute difference between the two AbsDon values may be
         greater than or equal to 1.

         Informative note: There are multiple reasons to allow for the
         absolute difference of the values of AbsDon for two consecutive
         NAL units in the NAL unit decoding order to be greater than
         one.  An increment by one is not required, as at the time of
         associating values of AbsDon to NAL units, it may not be known
         whether all NAL units are to be delivered to the receiver.  For
         example, a gateway may not forward VCL NAL units of higher sub-
         layers or some SEI NAL units when there is congestion in the
         network.  In another example, the first intra-coded picture of
         a pre-encoded clip is transmitted in advance to ensure that it
         is readily available in the receiver, and when transmitting the
         first intra-coded picture, the originator does not exactly know
         how many NAL units will be encoded before the first intra-coded
         picture of the pre-encoded clip follows in decoding order.
         Thus, the values of AbsDon for the NAL units of the first
         intra-coded picture of the pre-encoded clip have to be
         estimated when they are transmitted, and gaps in values of
         AbsDon may occur.  Another example is MRST or MRMT with sprop-
         max-don-diff greater than 0, where the AbsDon values must
         indicate cross-layer decoding order for NAL units conveyed in
         all the RTP streams.

5.  Packetization Rulesumber

   The following packetization rules apply:

   o  If sprop-max-don-diff is greater than 0 for any of the RTP
      streams, the transmission order of NAL units carried in the RTP
      stream MAY be different than the NAL unit decoding order and the
      NAL unit output order.  Otherwise (sprop-max-don-diff is equal to
      0 for all the RTP streams), the transmission order of NAL units
      carried in the RTP stream MUST be the same as the NAL unit
      decoding order and, when tx-mode is equal to "MRST" or "MRMT",
      MUST also be the same as the NAL unit output order.

   o  A NAL unit of a small size SHOULD be encapsulated in an
      aggregation packet together with one or more other NAL units in
      order to avoid the unnecessary packetization overhead for small
      NAL units.  For example, non-VCL NAL units such as access unit
      delimiters, parameter sets, or SEI NAL units are typically small



Zhao & Wenger             Expires March 6, 2020                [Page 25]


Internet-Draft         RTP Payload Format for VVC         September 2019


      and can often be aggregated with VCL NAL units without violating
      MTU size constraints.

   o  Each non-VCL NAL unit SHOULD, when possible from an MTU size match
      viewpoint, be encapsulated in an aggregation packet together with
      its associated VCL NAL unit, as typically a non-VCL NAL unit would
      be meaningless without the associated VCL NAL unit being
      available.

   o  For carrying exactly one NAL unit in an RTP packet, a single NAL
      unit packet MUST be used.

6.  De-packetization Process

   The general concept behind de-packetization is to get the NAL units
   out of the RTP packets in an RTP stream and all RTP streams the RTP
   stream depends on, if any, and pass them to the decoder in the NAL
   unit decoding order.

   The de-packetization process is implementation dependent.  Therefore,
   the following description should be seen as an example of a suitable
   implementation.  Other schemes may be used as well, as long as the
   output for the same input is the same as the process described below.
   The output is the same when the set of output NAL units and their
   order are both identical.  Optimizations relative to the described
   algorithms are possible.

   All normal RTP mechanisms related to buffer management apply.  In
   particular, duplicated or outdated RTP packets (as indicated by the
   RTP sequences number and the RTP timestamp) are removed.  To
   determine the exact time for decoding, factors such as a possible
   intentional delay to allow for proper inter-stream synchronization
   must be factored in.

   NAL units with NAL unit type values in the range of 0 to XX,
   inclusive, may be passed to the decoder.  NAL-unit-like structures
   with NAL unit type values in the range of XX to XX, inclusive, MUST
   NOT be passed to the decoder.

   The receiver includes a receiver buffer, which is used to compensate
   for transmission delay jitter within individual RTP streams and
   across RTP streams, to reorder NAL units from transmission order to
   the NAL unit decoding order, and to recover the NAL unit decoding
   order in MRST or MRMT, when applicable.  In this section, the
   receiver operation is described under the assumption that there is no
   transmission delay jitter within an RTP stream and across RTP
   streams.  To make a difference from a practical receiver buffer that
   is also used for compensation of transmission delay jitter, the



Zhao & Wenger             Expires March 6, 2020                [Page 26]


Internet-Draft         RTP Payload Format for VVC         September 2019


   receiver buffer is hereafter called the de-packetization buffer in
   this section.  Receivers should also prepare for transmission delay
   jitter; that is, either reserve separate buffers for transmission
   delay jitter buffering and de-packetization buffering or use a
   receiver buffer for both transmission delay jitter and de-
   packetization.  Moreover, receivers should take transmission delay
   jitter into account in the buffering operation, e.g., by additional
   initial buffering before starting of decoding and playback.

   When sprop-max-don-diff is equal to 0 for all the received RTP
   streams, the de-packetization buffer size is zero bytes, and the
   process described in the remainder of this paragraph applies.  When
   there is only one RTP stream received, the NAL units carried in the
   single RTP stream are directly passed to the decoder in their
   transmission order, which is identical to their decoding order.  When
   there is more than one RTP stream received, the NAL units carried in
   the multiple RTP streams are passed to the decoder in their NTP
   timestamp order.  When there are several NAL units of different RTP
   streams with the same NTP timestamp, the order to pass them to the
   decoder is their dependency order, where NAL units of a dependee RTP
   stream are passed to the decoder prior to the NAL units of the
   dependent RTP stream.  When there are several NAL units of the same
   RTP stream with the same NTP timestamp, the order to pass them to the
   decoder is their transmission order.

      Informative note: The mapping between RTP and NTP timestamps is
      conveyed in RTCP SR packets.  In addition, the mechanisms for
      faster media timestamp synchronization discussed in [RFC6051] may
      be used to speed up the acquisition of the RTP-to-wall-clock
      mapping.

   When sprop-max-don-diff is greater than 0 for any the received RTP
   streams, the process described in the remainder of this section
   applies.

   There are two buffering states in the receiver: initial buffering and
   buffering while playing.  Initial buffering starts when the reception
   is initialized.  After initial buffering, decoding and playback are
   started, and the buffering-while-playing mode is used.

   Regardless of the buffering state, the receiver stores incoming NAL
   units, in reception order, into the de-packetization buffer.  NAL
   units carried in RTP packets are stored in the de-packetization
   buffer individually, and the value of AbsDon is calculated and stored
   for each NAL unit.  When MRST or MRMT is in use, NAL units of all RTP
   streams of a bitstream are stored in the same de-packetization
   buffer.  When NAL units carried in any two RTP streams are available
   to be placed into the de-packetization buffer, those NAL units



Zhao & Wenger             Expires March 6, 2020                [Page 27]


Internet-Draft         RTP Payload Format for VVC         September 2019


   carried in the RTP stream that is lower in the dependency tree are
   placed into the buffer first.  For example, if RTP stream A depends
   on RTP stream B, then NAL units carried in RTP stream B are placed
   into the buffer first.

   Initial buffering lasts until condition A (the difference between the
   greatest 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 of the highest RTP stream) or condition B (the number of
   NAL units in the de-packetization buffer is greater than the value of
   sprop-depack-buf-nalus) is true.

   After initial buffering, whenever condition A or condition B is true,
   the following operation is repeatedly applied until both condition A
   and condition B become false:

   o  The NAL unit in the de-packetization buffer with the smallest
      value of AbsDon is removed from the de-packetization buffer and
      passed to the decoder.

   When no more NAL units are flowing into the de-packetization buffer,
   all NAL units remaining in the de-packetization buffer are removed
   from the buffer and passed to the decoder in the order of increasing
   AbsDon values.

7.  Payload Format Parameters

   Placeholder

8.  Use with Feedback Messages

   The following subsections define the use of the Picture Loss
   Indication (PLI), Slice Lost Indication (SLI), Reference Picture
   Selection Indication (RPSI), and Full Intra Request (FIR) feedback
   messages with HEVC.  The PLI, SLI, and RPSI messages are defined in
   [RFC4585] , and the FIR message is defined in [RFC5104] .

8.1.  Picture Loss Indication (PLI)

   As specified in RFC 4585, Section 6.3.1, the reception of a PLI by a
   media sender indicates "the loss of an undefined amount of coded
   video data belonging to one or more pictures".  Without having any
   specific knowledge of the setup of the bitstream (such as use and
   location of in-band parameter sets, non-IDR decoder refresh points,
   picture structures, and so forth), a reaction to the reception of an
   PLI by a [VVC] sender SHOULD be to send an IDR picture and relevant
   parameter sets; potentially with sufficient redundancy so to ensure
   correct reception.  However, sometimes information about the



Zhao & Wenger             Expires March 6, 2020                [Page 28]


Internet-Draft         RTP Payload Format for VVC         September 2019


   bitstream structure is known.  For example, state could have been
   established outside of the mechanisms defined in this document that
   parameter sets are conveyed out of band only, and stay static for the
   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
   examples could be devised based on a priori knowledge of different
   aspects of the bitstream structure.  In all cases, the timing and
   congestion control mechanisms of RFC 4585 MUST be observed.

8.2.  Slice Loss Indication (SLI)

   For further study.  Maybe remove as there are no known
   implementations of SDLI in H.265 based systems

8.3.  Reference Picture Selection Indication (RPSI)

   Feedback-based reference picture selection has been shown as a
   powerful tool to stop temporal error propagation for improved error
   resilience [Girod99] [Wang05].  In one approach, the decoder side
   tracks errors in the decoded pictures and informs the encoder side
   that a particular picture that has been decoded relatively earlier is
   correct and still present in the decoded picture buffer; it requests
   the encoder to use that correct picture-availability information when
   encoding the next picture, so to stop further temporal error
   propagation.  For this approach, the decoder side should use the RPSI
   feedback message.

   Encoders can encode some long-term reference pictures as specified in
   [VVC] for purposes described in the previous paragraph without the
   need of a huge decoded picture buffer.  As shown in [Wang05], with a
   flexible reference picture management scheme, as in [VVC], even a
   decoded picture buffer size of two picture storage buffers would work
   for the approach described in the previous paragraph.

   the text below is copy-paste from RFC 7798.  If we keep the RPSI
   message, it needs adaptation to the [VVC] syntax.  Doing so shouldn't
   be too hard as the [VVC] reference picture mechanism is not too
   different from the H.265 one.

8.4.  Full Intra Request (FIR)

   The purpose of the FIR message is to force an encoder to send an
   independent decoder refresh point as soon as possible (observing, for
   example, the congestion-control-related constraints set out in RFC
   5104).

   Upon reception of a FIR, a sender MUST send an IDR picture.
   Parameter sets MUST also be sent, except when there is a priori



Zhao & Wenger             Expires March 6, 2020                [Page 29]


Internet-Draft         RTP Payload Format for VVC         September 2019


   knowledge that the parameter sets have been correctly established.  A
   typical example for that is an understanding between sender and
   receiver, established by means outside this document, that parameter
   sets are exclusively sent out-of-band.

9.  Security Considerations

   The scope of this Security Considerations section is limited to the
   payload format itself and to one feature of [VVC] that may pose a
   particularly serious security risk if implemented naively.  The
   payload format, in isolation, does not form a complete system.
   Implementers are advised to read and understand relevant security-
   related documents, especially those pertaining to RTP (see the
   Security Considerations section in [RFC3550] ), and the security of
   the call-control stack chosen (that may make use of the media type
   registration of this memo).  Implementers should also consider known
   security vulnerabilities of video coding and decoding implementations
   in general and avoid those.

   Within this RTP payload format, and with the exception of the user
   data SEI message as described below, no security threats other than
   those common to RTP payload formats are known.  In other words,
   neither the various media-plane-based mechanisms, nor the signaling
   part of this memo, seems to pose a security risk beyond those common
   to all RTP-based systems.

   RTP packets using the payload format defined in this specification
   are subject to the security considerations discussed in the RTP
   specification [RFC3550] , and in any applicable RTP profile such as
   RTP/AVP [RFC3551] , RTP/AVPF [RFC4585] , RTP/SAVP [RFC3711] , or RTP/
   SAVPF [RFC5124] .  However, as "Securing the RTP Framework: Why RTP
   Does Not Mandate a Single Media Security Solution" [RFC7202]
   discusses, it is not an RTP payload format's responsibility to
   discuss or mandate what solutions are used to meet the basic security
   goals like confidentiality, integrity and source authenticity for RTP
   in general.  This responsibility lays on anyone using RTP in an
   application.  They can find guidance on available security mechanisms
   and important considerations in "Options for Securing RTP Sessions"
   [RFC7201] .  Applications SHOULD use one or more appropriate strong
   security mechanisms.  The rest of this section discusses the security
   impacting properties of the payload format itself.

   Because the data compression used with this payload format is applied
   end-to-end, any encryption needs to be performed after compression.
   A potential denial-of-service threat exists for data encodings using
   compression techniques that have non-uniform receiver-end
   computational load.  The attacker can inject pathological datagrams
   into the bitstream that are complex to decode and that cause the



Zhao & Wenger             Expires March 6, 2020                [Page 30]


Internet-Draft         RTP Payload Format for VVC         September 2019


   receiver to be overloaded.  [VVC] is particularly vulnerable to such
   attacks, as it is extremely simple to generate datagrams containing
   NAL units that affect the decoding process of many future NAL units.
   Therefore, the usage of data origin authentication and data integrity
   protection of at least the RTP packet is RECOMMENDED, for example,
   with SRTP [RFC3711] .

   Like HEVC [RFC7798], [VVC] includes a user data Supplemental
   Enhancement Information (SEI) message.  This SEI message allows
   inclusion of an arbitrary bitstring into the video bitstream.  Such a
   bitstring could include JavaScript, machine code, and other active
   content.  [VVC] leaves the handling of this SEI message to the
   receiving system.  In order to avoid harmful side effects rganization
   the user data SEI message, decoder implementations cannot naively
   trust its content.  For example, it would be a bad and insecure
   implementation practice to forward any JavaScript a decoder
   implementation detects to a web browser.  The safest way to deal with
   user data SEI messages is to simply discard them, but that can have
   negative side effects on the quality of experience by the user.

   End-to-end security with authentication, integrity, or
   confidentiality protection will prevent a MANE from performing media-
   aware operations other than discarding complete packets.  In the case
   of confidentiality protection, it will even be prevented from
   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
   included in the security context establishment.

10.  Congestion Control

   Congestion control for RTP SHALL be used in accordance with RTP
   [RFC3550] and with any applicable RTP profile, e.g., AVP [RFC3551] .
   If best-effort service is being used, an additional requirement is
   that users of this payload format MUST monitor packet loss to ensure
   that the packet loss rate is within an acceptable range.  Packet loss
   is considered acceptable if a TCP flow across the same network path,
   and experiencing the same network conditions, would achieve an
   average throughput, measured on a reasonable timescale, that is not
   less than all RTP streams combined is achieving.  This condition can
   be satisfied by implementing congestion-control mechanisms to adapt
   the transmission rate, the number of layers subscribed for a layered
   multicast session, or by arranging for a receiver to leave the
   session if the loss rate is unacceptably high.

   The bitrate adaptation necessary for obeying the congestion control
   principle is easily achievable when real-time encoding is used, for
   example, by adequately tuning the quantization parameter.




Zhao & Wenger             Expires March 6, 2020                [Page 31]


Internet-Draft         RTP Payload Format for VVC         September 2019


   However, when pre-encoded content is being transmitted, bandwidth
   adaptation requires the pre-coded bitstream to be tailored for such
   adaptivity.  The key mechanisms available in [VVC] are temporal
   scalability, and spatial/SNR scalability.  A media sender can remove
   NAL units belonging to higher temporal sub-layers (i.e., those NAL
   units with a high value of TID) or higher spatio-SNR layers (as
   indicated by interpreting the VPS) until the sending bitrate drops to
   an acceptable range.

   Above mechanisms generally work within a defined profile and level
   and, therefore, no renegotiation of the channel is required.  Only
   when non-downgradable parameters (such as profile) are required to be
   changed does it become necessary to terminate and restart the RTP
   stream(s).  This may be accomplished by using different RTP payload
   types.

   MANEs MAY remove certain unusable packets from the RTP stream when
   that RTP stream was damaged due to previous packet losses.  This can
   help reduce the network load in certain special cases.  For example,
   MANES can remove those FUs where the leading FUs belonging to the
   same NAL unit have been lost or those dependent slice segments when
   the leading slice segments belonging to the same slice have been
   lost, because the trailing FUs or dependent slice segments are
   meaningless to most decoders.  MANES can also remove higher temporal
   scalable layers if the outbound transmission (from the MANE's
   viewpoint) experiences congestion.

11.  IANA Considertaions

   Placeholder

12.  Acknowledgements

   Large parts of this specification share text with the RTP payload
   format for HEVC [RFC7798], RFC 7798.  We thank the authors of that
   specification for their excellent work.  We also thank BD Choi for
   his contribution towards the [VVC] descriptive text.

13.  References

13.1.  Normative References

   [ISO23090-3]
              ISO and IEC, "Versatile video coding -- not yet
              published", August 2020.






Zhao & Wenger             Expires March 6, 2020                [Page 32]


Internet-Draft         RTP Payload Format for VVC         September 2019


   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
              July 2003, <https://www.rfc-editor.org/info/rfc3550>.

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", STD 65, RFC 3551,
              DOI 10.17487/RFC3551, July 2003,
              <https://www.rfc-editor.org/info/rfc3551>.

   [RFC3711]  Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol (SRTP)",
              RFC 3711, DOI 10.17487/RFC3711, March 2004,
              <https://www.rfc-editor.org/info/rfc3711>.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
              July 2006, <https://www.rfc-editor.org/info/rfc4566>.

   [RFC4585]  Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
              "Extended RTP Profile for Real-time Transport Control
              Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
              DOI 10.17487/RFC4585, July 2006,
              <https://www.rfc-editor.org/info/rfc4585>.

   [RFC5104]  Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
              "Codec Control Messages in the RTP Audio-Visual Profile
              with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
              February 2008, <https://www.rfc-editor.org/info/rfc5104>.

   [RFC5124]  Ott, J. and E. Carrara, "Extended Secure RTP Profile for
              Real-time Transport Control Protocol (RTCP)-Based Feedback
              (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
              2008, <https://www.rfc-editor.org/info/rfc5124>.

   [VVC]      ITU-T, "Versatile video coding - JVET-O2001-vE, available
              from http://phenix.it-
              sudparis.eu/jvet/doc_end_user/documents/15_Gothenburg/
              wg11/JVET-O2001-v14.zip", August 2019.







Zhao & Wenger             Expires March 6, 2020                [Page 33]


Internet-Draft         RTP Payload Format for VVC         September 2019


13.2.  Informative References

   [CABAC]    Sole, J., Joshi, R., Nguyen, N., Ji, T., Karczewicz, M.,
              Clare, G., Henry, F., and A. Duenas, "Transform
              coefficient coding in HEVC", IEEE Transactions on Circuts
              and Systems for Video Technology Vol. 22 No. 12 pp.
              1765-1777, DOI 10.1109/TCSVT.2012.2223055, December 2012.

   [Girod99]  Girod, B. and F. Faerber, "Feedback-based error control
              for mobile video transmission", Proceedings of the
              IEEE Vol. 87, No. 10, pp. 1707-1723, DOI 10.1109/5.790632,
              October 1999.

   [MPEG2S]   IS0/IEC, "Information technology - Generic coding of
              moving pictures and associated audio information - Part 1:
              Systems", ISO International Standard 13818-1, 2013.

   [RFC6051]  Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP
              Flows", RFC 6051, DOI 10.17487/RFC6051, November 2010,
              <https://www.rfc-editor.org/info/rfc6051>.

   [RFC6184]  Wang, Y., Even, R., Kristensen, T., and R. Jesup, "RTP
              Payload Format for H.264 Video", RFC 6184,
              DOI 10.17487/RFC6184, May 2011,
              <https://www.rfc-editor.org/info/rfc6184>.

   [RFC6190]  Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
              "RTP Payload Format for Scalable Video Coding", RFC 6190,
              DOI 10.17487/RFC6190, May 2011,
              <https://www.rfc-editor.org/info/rfc6190>.

   [RFC7201]  Westerlund, M. and C. Perkins, "Options for Securing RTP
              Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
              <https://www.rfc-editor.org/info/rfc7201>.

   [RFC7202]  Perkins, C. and M. Westerlund, "Securing the RTP
              Framework: Why RTP Does Not Mandate a Single Media
              Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
              2014, <https://www.rfc-editor.org/info/rfc7202>.

   [RFC7798]  Wang, Y., Sanchez, Y., Schierl, T., Wenger, S., and M.
              Hannuksela, "RTP Payload Format for High Efficiency Video
              Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, March
              2016, <https://www.rfc-editor.org/info/rfc7798>.







Zhao & Wenger             Expires March 6, 2020                [Page 34]


Internet-Draft         RTP Payload Format for VVC         September 2019


Appendix A.  Change History

   draft-zhao-payload-rtp-vvc-00 ........ initial version

Authors' Addresses

   Shuai Zhao
   Tencent
   2747 Park Blvd.
   Palo Alto, CA  94306
   US

   Email: shuaiizhao@tencent.com


   Stephan Wenger
   Tencent
   2747 Park Blvd.
   Palo Alto, CA  94306
   US

   Email: stewe@stewe.org





























Zhao & Wenger             Expires March 6, 2020                [Page 35]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/