avtcore                                                         L. Ilola
Internet-Draft                                                L. Kondrad
Intended status: Standards Track                      Nokia Technologies
Expires: 28 October 2022                                   26 April 2022


   RTP Payload Format for Visual Volumetric Video-based Coding (V3C)
                     draft-ilola-avtcore-rtp-v3c-01

Abstract

   This memo describes an RTP payload format for visual volumetric
   video-based coding (V3C) [ISO.IEC.23090-5].  A V3C bitstream is
   composed of V3C units that contain V3C video sub-bitstreams, V3C
   atlas sub-bitstreams, or a V3C parameter set.  The RTP payload format
   for V3C video sub-bitstreams is defined by appropriate Internet
   Standards for the applicable video codec.  The RTP payload format for
   V3C atlas sub-bitstreams is described by this memo.  The RTP payload
   format allows for packetization of one or more V3C Network
   Abstraction Layer (NAL) units in a RTP packet payload as well as
   fragmentation of a V3C NAL unit into multiple RTP packets.  The memo
   also describes the mechanisms for grouping RTP streams of V3C
   component sub-bitstreams, providing a complete solution for streaming
   V3C bitstream.

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 28 October 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





Ilola & Kondrad          Expires 28 October 2022                [Page 1]


Internet-Draft         RTP payload format for V3C             April 2022


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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Definitions, and Abbreviations  . . . . . . . . . . . . . . .   4
     3.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   4
       3.1.1.  General . . . . . . . . . . . . . . . . . . . . . . .   4
       3.1.2.  Definitions from the V3C Specification  . . . . . . .   4
       3.1.3.  Definitions Specific to This Memo . . . . . . . . . .   6
     3.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Media Format Description  . . . . . . . . . . . . . . . . . .   6
     4.1.  Overview of the V3C codec . . . . . . . . . . . . . . . .   7
     4.2.  V3C parameter set . . . . . . . . . . . . . . . . . . . .   8
     4.3.  V3C atlas and video components  . . . . . . . . . . . . .   8
       4.3.1.  General . . . . . . . . . . . . . . . . . . . . . . .   8
       4.3.2.  Atlas NAL units . . . . . . . . . . . . . . . . . . .  10
     4.4.  Systems and transport interfaces  . . . . . . . . . . . .  11
   5.  V3C Atlas RTP payload format  . . . . . . . . . . . . . . . .  11
     5.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .  11
     5.2.  RTP Header  . . . . . . . . . . . . . . . . . . . . . . .  11
     5.3.  RTP payload header  . . . . . . . . . . . . . . . . . . .  13
     5.4.  Transmission modes  . . . . . . . . . . . . . . . . . . .  14
     5.5.  Payload structures  . . . . . . . . . . . . . . . . . . .  14
       5.5.1.  General . . . . . . . . . . . . . . . . . . . . . . .  15
       5.5.2.  Single NAL unit packet  . . . . . . . . . . . . . . .  15
       5.5.3.  Aggregation packet  . . . . . . . . . . . . . . . . .  17
       5.5.4.  Fragmentation unit  . . . . . . . . . . . . . . . . .  19
     5.6.  Decoding Order Number . . . . . . . . . . . . . . . . . .  21
   6.  Packetization and de-packetization rules  . . . . . . . . . .  22
   7.  Payload Examples  . . . . . . . . . . . . . . . . . . . . . .  23
     7.1.  General . . . . . . . . . . . . . . . . . . . . . . . . .  23
     7.2.  V3C fragmentation unit  . . . . . . . . . . . . . . . . .  23
   8.  Payload Format Parameters . . . . . . . . . . . . . . . . . .  25
     8.1.  Media Type Definition . . . . . . . . . . . . . . . . . .  25
   9.  Congestion Control Considerations . . . . . . . . . . . . . .  29
   10. Session Description Protocol  . . . . . . . . . . . . . . . .  29
     10.1.  Mapping of payload type parameters to SDP  . . . . . . .  29
       10.1.1.  For V3C atlas components . . . . . . . . . . . . . .  29
       10.1.2.  For V3C video components . . . . . . . . . . . . . .  30



Ilola & Kondrad          Expires 28 October 2022                [Page 2]


Internet-Draft         RTP payload format for V3C             April 2022


     10.2.  Grouping Framework . . . . . . . . . . . . . . . . . . .  31
     10.3.  Offer/Answer Considerations  . . . . . . . . . . . . . .  33
     10.4.  Declarative SDP Considerations . . . . . . . . . . . . .  36
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  36
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  36
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  37
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  37
     13.2.  Informative References . . . . . . . . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40

1.  Introduction

   Volumetric video, similar to traditional 2D video, when uncompressed,
   is represented by a large amount of data.  The Visual Volumetric
   Video-based Coding (V3C) specification [ISO.IEC.23090-5] leverages
   the compression efficiency of existing 2D video codecs to reduce the
   amount of data needed for storage and transmission of volumetric
   video.

   V3C encoder converts volumetric frames, 3D volumetric information,
   into a collection of 2D images and associated data, known as atlas
   data.  The converted 2D images are subsequently coded using existing
   video or image codecs, e.g.  ISO/IEC International Standard 14496-10
   [ISO.IEC.14496-10], ISO/IEC International Standard 23008-2
   [ISO.IEC.23008-2] or ISO/IEC International Standard 23090-3
   [ISO.IEC.23090-3].  The atlas data is coded with mechanisms specified
   in [ISO.IEC.23090-5].  V3C is generic mechanism for volumetric video
   coding and it can be used by applications targeting volumetric
   content, such as point clouds, immersive video with depth, mesh
   representations of visual volumetric frames, etc.  Examples of such
   applications are Video-based Point Cloud Compression (V-PCC)
   [ISO.IEC.23090-5], and MPEG Immersive Video (MIV) [ISO.IEC.23090-12].

   V3C utilizes high level syntax (HLS) syntax design known from
   traditional 2D video codecs to represent the associated coded data,
   i.e. atlas data.  The atlas data is represented by Network
   Abstraction Layer (NAL) units.  Consequently, RTP payload format for
   V3C atlas data described in this memo shares design philosophy,
   security, congestion control, and overall implementation complexity
   with other the NAL unit-based RTP payload formats such as the ones
   defined in [RFC6184], [RFC6190], and [RFC7798].

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 [RFC2119].




Ilola & Kondrad          Expires 28 October 2022                [Page 3]


Internet-Draft         RTP payload format for V3C             April 2022


   All fields defined in this specification related to RTP payload
   structures SHALL be considered in network order.

3.  Definitions, and Abbreviations

3.1.  Definitions

3.1.1.  General

   This document uses the definitions of [ISO.IEC.23090-5].  The
   following terms, defined in [ISO.IEC.23090-5], are provided here for
   convenience:

3.1.2.  Definitions from the V3C Specification

   atlas: collection of 2D bounding boxes and their associated
   information placed onto a rectangular frame and corresponding to a
   volume in 3D space on which volumetric data is rendered.

   atlas bitstream: sequence of bits that forms the representation of
   atlas frames and associated data forming one or more CASs.

   atlas coding layer NAL unit: collective term for coded atlas tile
   layer NAL units and the subset of NAL units that have reserved values
   of nal_unit_type that are classified as being of type class equal to
   ACL in this document.

   atlas frame: 2D rectangular array of atlas samples onto which patches
   are projected and additional information related to the patches,
   corresponding to a volumetric frame.

   atlas frame parameter set: syntax structure containing syntax
   elements that apply to zero or more entire coded atlas frames as
   determined by the content of a syntax element found in each tile
   header.

   atlas sequence parameter set: syntax structure containing syntax
   elements that apply to zero or more entire coded atlas sequences as
   determined by the content of a syntax element found in the AFPS
   referred to by a syntax element found in each tile header.

   attribute: scalar or vector property optionally associated with each
   point in a volumetric frame such as colour, reflectance, surface
   normal, time stamps, material ID, etc.

   coded atlas sequence: sequence of coded atlas access units, in
   decoding order, of an IRAP coded atlas access unit, followed by zero
   or more coded atlas access units that are not IRAP coded atlas access



Ilola & Kondrad          Expires 28 October 2022                [Page 4]


Internet-Draft         RTP payload format for V3C             April 2022


   units, including all subsequent access units up to but not including
   any subsequent coded atlas access unit that is an IRAP coded atlas
   access unit.

   coded atlas access unit: set of atlas NAL units that are associated
   with each other according to a specified classification rule, are
   consecutive in decoding order, and contain all atlas NAL units
   pertaining to one particular output time.

   intra random access point coded atlas: coded atlas for which each ACL
   NAL unit has nal_unit_type in the range of NAL_BLA_W_LP to
   NAL_RSV_IRAP_ACL_29, inclusive.

   intra random access point coded atlas access unit: access unit in
   which the coded atlas with nal_layer_id equal to 0 is a IRAP coded
   atlas.

   network abstraction layer unit: syntax structure containing an
   indication of the type of data to follow and bytes containing that
   data in the form of an RBSP.

   patch: rectangular region within an atlas associated with volumetric
   information.

   raw byte sequence payload: syntax structure containing an integer
   number of bytes that is encapsulated in a NAL unit and that is either
   empty or has the form of a string of data bits containing syntax
   elements followed by an RBSP stop bit and zero or more subsequent
   bits equal to 0.

   tile: independently decodable rectangular region of an atlas frame

   visual volumetric video-based coding atlas sub-bitstream: extracted
   sub-bitstream from the V3C bitstream containing whole or portion of
   an atlas bitstream.

   visual volumetric video-based coding video sub-bitstream: extracted
   sub-bitstream from the V3C bitstream containing whole or portion of
   an video bitstream.

   visual volumetric video-based coding component: atlas, occupancy,
   geometry, or attribute of a particular type that is associated with a
   V3C volumetric content representation.

   visual volumetric video-based coding parameter set: syntax structure
   containing syntax elements that apply to zero or more entire CVSs and
   may be referred to by syntax elements found in the V3C unit header




Ilola & Kondrad          Expires 28 October 2022                [Page 5]


Internet-Draft         RTP payload format for V3C             April 2022


   volumetric frame: set of 3D points specified by their cartesian
   coordinates and zero or more corresponding sets of attributes at a
   particular time instance.

3.1.3.  Definitions Specific to This Memo

   Placeholder

3.2.  Abbreviations

   ACL atlas coding layer

   AFPS atlas frame parameter set

   AP aggregation packet

   ASPS atlas sequence parameter set

   AU aggregation unit

   CAS coded atlas sequence

   DON decoding order number

   IRAP intra random access point

   MRMT Multiple RTP streams on Multiple media Transports

   MRST Multiple RTP streams over a Single media Transport

   MTU maximum transmission unit

   NAL network abstraction layer

   NALU NAL unit

   RBSP raw byte sequence payload

   SRST Single RTP stream on a Single media Transport

   V3C visual volumetric video-based coding

   VPS V3C parameter set

4.  Media Format Description






Ilola & Kondrad          Expires 28 October 2022                [Page 6]


Internet-Draft         RTP payload format for V3C             April 2022


4.1.  Overview of the V3C codec

   ISO/IEC International Standards 23090-5 [ISO.IEC.23090-5] enables
   encoding and decoding processes of volumetric video which utilizes 2D
   video coding technologies and associated data.  V3C encoding of
   volumetric frame is achieved through a conversion of volumetric frame
   from its 3D representation to multiple 2D representations and a
   generation of associated data.

   2D representations, known as V3C video components, of volumetric
   frame are encoded using traditional 2D video codecs.  V3C video
   component may, for example, include occupancy, geometry, or attribute
   data.  The occupancy data informs a V3C decoder which pixels in other
   V3C video components contribute to reconstructed 3D representation.
   The geometry data describes information on the position of the
   reconstructed voxels, while attribute data provides properties of
   that voxel, e.g. color or material information.

   Atlas data, known as V3C atlas component, provides information to
   interpret V3C video components and enables the reconstruction from a
   2D representation back into a 3D representation of volumetric frame.
   Atlas data is composed of a collection of patches.  Each patch
   identifies a region in all V3C video components and provides
   information necessary to perform the appropriate inverse projection
   of the indicated region back into 3D space.  The shape of the patch
   region is determined by a 2D bounding box associated with each patch
   as well as their coding order.  The shape of these patches is also
   further refined based on occupancy data.

   To enable parallelization, random access, as well as a variety of
   other functionalities, an atlas frame can be divided into one or more
   rectangular partitions referred to as tiles.  Tiles are not allowed
   to overlap and SHOULD be independently decodeable.  An atlas frame
   may contain regions that are not associated with any tile or patch.

   The binary form of V3C video components, i.e. video bitstream, and
   V3C atlas components, i.e. V3C atlas bitstream, can be grouped and
   represented by a single V3C bitstream.  The V3C bitstream is composed
   of a set of V3C units.  Each V3C unit has a V3C unit header and a V3C
   unit payload.  The V3C unit header describes the V3C unit type for
   the payload.  V3C unit payload contains V3C video components, V3C
   atlas components or V3C parameter set.  V3C video component, i.e.
   occupancy, geometry, and attribute, corresponds to video data units
   (e.g.  NAL units defined in [ISO.IEC.23008-2]) that could be decoded
   by an appropriate video decoder.






Ilola & Kondrad          Expires 28 October 2022                [Page 7]


Internet-Draft         RTP payload format for V3C             April 2022


4.2.  V3C parameter set

   While this memo intends to describe encapsulation of V3C atlas data,
   aspects related to signaling of V3C parameter set need to be
   considered.  V3C parameter set is signaled in its own V3C unit, which
   allows decoupling the transmission of V3C parameter set from the V3C
   video and atlas components.  V3C parameter set can be transmitted by
   external means (e.g., as a result of the capability exchange) or
   through a (reliable or unreliable) control protocol.  This memo
   provides information how V3C parameter set can be signaled as part of
   session description protocol, see Section 10.

4.3.  V3C atlas and video components

4.3.1.  General

   In V3C bitstream the atlas component is identified by vuh_unit_type
   equal to V3C_AD in the V3C unit header.  The V3C atlas component
   consists of atlas NAL units that define header and payload pairs and
   are described in Section 4.3.2.  V3C video components are identified
   by vuh_unit_type equal to V3C_OVD, V3C_GVD, V3C_AVD, and V3C_PVD
   respectively.  V3C video components can be further separated by other
   values in the V3C unit header such as vuh_attribute_index,
   vuh_attribute_index, vuh_attribute_partition_index, vuh_map_index and
   vuh_auxiliary_video_flag.  By mapping V3C parameter set information
   to vuh_attribute_index, a V3C decoder identifies which attribute a
   given V3C video component contains, e.g. color.

   The information supplied by V3C unit header SHOULD be provided in one
   form or another to a V3C decoder, e.g. as part of SDP as described in
   this memo in Section 10.  The four-byte V3C unit header syntax and
   semantics are copied below as defined in [ISO.IEC.23090-5].



















Ilola & Kondrad          Expires 28 October 2022                [Page 8]


Internet-Draft         RTP payload format for V3C             April 2022


   v3c_unit_header( ) {
    unsigned int(5) vuh_unit_type;
    if( vuh_unit_type == V3C_AVD || vuh_unit_type == V3C_GVD ||
      vuh_unit_type == V3C_OVD || vuh_unit_type == V3C_AD ||
      vuh_unit_type == V3C_CAD || vuh_unit_type == V3C_PVD ) {
      unsigned int(4) vuh_v3c_parameter_set_id;
     }
     if( vuh_unit_type == V3C_AVD || vuh_unit_type == V3C_GVD ||
       vuh_unit_type == V3C_OVD || vuh_unit_type == V3C_AD ||
       vuh_unit_type == V3C_PVD ) {
       unsigned int(6) vuh_atlas_id;
     }
     if( vuh_unit_type == V3C_AVD ) {
       unsigned int(7) vuh_attribute_index;
       unsigned int(5) vuh_attribute_partition_index;
       unsigned int(4) vuh_map_index;
       unsigned int(1) vuh_auxiliary_video_flag;
     }
     if( vuh_unit_type == V3C_GVD ) {
       unsigned int(4) vuh_map_index;
       unsigned int(1) vuh_auxiliary_video_flag;
       bit(12) vuh_reserved_zero_12bits;
     }
     if( vuh_unit_type == V3C_OVD || vuh_unit_type == V3C_AD ||
         vuh_unit_type == V3C_PVD) {
       bit(17) vuh_reserved_zero_17bits;
     } else {
       bit(27) vuh_reserved_zero_27bits;
     }
   }

   vuh_unit_type indicates the V3C unit type for the V3C component as
   specified in [ISO.IEC.23090-5].

   vuh_v3c_parameter_set_id specifies the value of
   vps_v3c_parameter_set_id for the active V3C VPS.

   vuh_atlas_id specifies the ID of the atlas that corresponds to the
   current V3C unit.

   vuh_attribute_index indicates the index of the attribute data carried
   in the Attribute Video Data unit.

   vuh_attribute_partition_index indicates the index of the attribute
   dimension group carried in the attribute video data unit.






Ilola & Kondrad          Expires 28 October 2022                [Page 9]


Internet-Draft         RTP payload format for V3C             April 2022


   vuh_map_index when present indicates the map index of the current
   geometry or attribute stream.  When not present, the map index of the
   current geometry or attribute sub-bitstream is derived based on the
   type of the sub-bitstream.

   vuh_auxiliary_video_flag equal indicates if the associated geometry
   or attribute video data unit is a RAW and/or EOM coded points video
   only sub-bitstream.

4.3.2.  Atlas NAL units

   Atlas NAL unit (nal_unit(NumBytesInNalUnit)) is a byte-aligned syntax
   structure defined by [ISO.IEC.23090-5] to carry atlas data. atlas NAL
   unit always contains a 16-bit NAL unit header (nal_unit_header()),
   which indicates among other things the type of the NAL unit
   (nal_unit_type).  The sample code below describes the NAL unit
   syntax, including the NAL unit header.

   nal_unit_header(){
       bit(1) nal_forbidden_zero_bit;
       bit(6) nal_unit_type;
       bit(6) nal_layer_id;
       bit(3) nal_temporal_id_plus1;
   }
   nal_unit(NumBytesInNalUnit){
       nal_unit_header();
       NumBytesInRbsp = 0;
       for( i = 2; i < NumBytesInNalUnit; i++ )
         bit(8) rbsp_byte[ NumBytesInRbsp++ ];
   }

   nal_forbidden_zero_bit MUST be equal to 0.  (F)

   nal_unit_type indicates the type of the RBSP data structure contained
   in the NAL unit (NUT)

   nal_layer_id indicates the identifier of the layer to which an ACL
   NAL unit belongs or the identifier of a layer to which a non-ACL NAL
   unit applies.  (NLI)

   nal_temporal_id_plus1 minus 1 indicates a temporal identifier for the
   NAL unit.  The value of nal_temporal_id_plus1 MUST NOT be equal to 0.
   (TID)








Ilola & Kondrad          Expires 28 October 2022               [Page 10]


Internet-Draft         RTP payload format for V3C             April 2022


4.4.  Systems and transport interfaces

   In addition to releasing specifications on V3C [ISO.IEC.23090-5] and
   [ISO.IEC.23090-12], MPEG is conducting further systems level work on
   file format level to encapsulate compressed V3C content.  The seventh
   edition of the ISOBMFF specification [ISO.IEC.14496-12] introduces a
   new media handler 'volv', intended to support volumetric visual
   media.  It also specifies other structures to enable development of
   derived specifications detailing how various volumetric visual media
   may be stored in ISOBMFF.

   One of such derived specifications is [ISO.IEC.23090-10], which
   focuses on defining how V3C content SHOULD be stored in a file and
   streamed over DASH.  To a large extent ISO/IEC 23090-10 focuses on
   describing how ISOBMFF boxes and syntax elements may be used to store
   volumetric media, but in some cases new boxes and syntax elements are
   introduced to accommodate the fundamentally different type of new
   media.  While the specification is not directly relevant for defining
   RTP payload format for V3C atlas data, it is a useful resource that
   SHOULD be considered especially when desiging ingestion of encoded
   V3C content into RTP streaming pipelines.

5.  V3C Atlas RTP payload format

5.1.  General

   This section describes details related to V3C atlas RTP payload
   defintions.  Aspects related to RTP header, RTP payload header and
   general payload structure are considered along with different
   packetization modes.

5.2.  RTP Header

   The format of the RTP header is specified in [RFC3550] and replicated
   below in Figure 1 for convenience.  This payload format uses the
   fields of the header in a manner consistent with that specification.















Ilola & Kondrad          Expires 28 October 2022               [Page 11]


Internet-Draft         RTP payload format for V3C             April 2022


       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             |
       |                             ....                              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            Figure 1: RTP Header

   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.

   When MRST or MRMT is in use, if an access unit appears in multiple
   RTP streams, the marker bit is set on each RTP stream's last packet
   of the access unit.

   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.

   NOTE: (informative) It is not required to use different payload type
   values for different RTP streams in MRST or MRMT.

   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.





Ilola & Kondrad          Expires 28 October 2022               [Page 12]


Internet-Draft         RTP payload format for V3C             April 2022


   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 case the
   NAL unit (according to Section 8.4.5.3 of [ISO.IEC.23090-5]) is
   included.

   Receivers MUST use the RTP timestamp for the display process, even
   when the bitstream contains atlas frame timing SEI messages as
   specified in [ISO.IEC.23090-5].

   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.  In MRST or MRMT, different SSRCs are used for
   each RTP stream containing a subset of the sub-layers of the single
   (temporally scalable) bitstream.  A receiver is required to correctly
   associate the set of SSRCs that are included parts of the same
   bitstream.

   The remaining RTP header fields are used as specified in [RFC3550].

5.3.  RTP payload header

   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, NUT, NLI, and TID) as the NAL unit header as shown in
   Section 4.3.2, irrespective of the type of the payload structure.
   For convenience the structure of RTP payload header is described
   below in Figure 2.

       0                   1
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |F|    NUT    |    NLI    | TID |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 2: RTP Payload Header

   F: nal_forbidden_zero_bit as specified in [ISO.IEC.23090-5] MUST be
   equal to 0.

   NUT: nal_unit_type as specified in [ISO.IEC.23090-5] defines the type
   of the RBSP data structure contained in the NAL unit.  NUT value
   could carry other meaning depending on the RTP packet type.





Ilola & Kondrad          Expires 28 October 2022               [Page 13]


Internet-Draft         RTP payload format for V3C             April 2022


   NLI: nal_layer_id as specified in [ISO.IEC.23090-5] defines the
   identifier of the layer to which an ACL NAL unit belongs or the
   identifier of a layer to which a non-ACL NAL unit applies.

   TID: nal_temporal_id_plus1 minus 1 as specified in [ISO.IEC.23090-5]
   defines a temporal identifier for the NAL unit.  The value of
   nal_temporal_id_plus1 MUST NOT be equal to 0.

5.4.  Transmission modes

   This memo enables transmission of an V3C atlas bitstream over:

   *  a Single RTP stream on a Single media Transport (SRST),

   *  Multiple RTP streams over a Single media Transport (MRST), or

   *  Multiple RTP streams on Multiple media Transports (MRMT).

   When in MRST or MRMT, multiple RTP streams may be grouped together as
   specified in [RFC5888] and [RFC9143].

   SRST or MRST SHOULD be used for point-to-point unicast scenarios,
   whereas MRMT SHOULD be used for point-to-multipoint multicast
   scenarios where different receivers require different operation
   points of the same V3C atlas bitstream, to improve bandwidth
   utilizing efficiency.

   NOTE: A multicast may degrade to a unicast at some point when only
   one receiver has left.  This is a justification of the first "SHOULD"
   instead of "MUST".  There might be scenarios where MRMT is desirable
   but not possible, e.g., when IP multicast is not deployed in certain
   network.  This is a justification of the second "SHOULD" instead of
   "MUST".

   The transmission mode is indicated by the tx-mode media parameter.
   If tx-mode is equal to "SRST", SRST MUST be used.  Otherwise, if tx-
   mode is equal to "MRST", MRST MUST be used.  Otherwise (tx-mode is
   equal to "MRMT"), MRMT MUST be used.

   NOTE: (informative) When an RTP stream does not depend on other RTP
   streams, any of SRST, MRST, or MRMT may be in use for the RTP stream.

   Receivers MUST support all of SRST, MRST, and MRMT.  The required
   support of MRMT by receivers does not imply that multicast must be
   supported by receivers.

5.5.  Payload structures




Ilola & Kondrad          Expires 28 October 2022               [Page 14]


Internet-Draft         RTP payload format for V3C             April 2022


5.5.1.  General

   Three different types of RTP packet payload structures are specified.
   A receiver can identify the payload structure by the first two bytes
   of the RTP packet payload, which co-serves as the RTP payload header.
   These two bytes are always structured as a NAL unit header.  The NAL
   unit type field indicates which structure is present in the payload.

   The three different payload structures are as follows:

   *  Single NAL Unit Packet: Contains a single NAL unit in the payload.
      This payload structure is specified in Section 5.5.2.

   *  Aggregation Packet: Contains multiple NAL units in a single RTP
      payload.  This payload structure is specified in Section 5.5.3.

   *  Fragmentation Unit: Contains a subset of a single NAL unit.  This
      payload structure is specified in Section 5.5.4.

   NOTE: (informative) This specification does not limit the size of NAL
   units encapsulated in NAL unit packets and fragmentation units.
   [ISO.IEC.23090-5] does not restrict the maximum size of a NAL unit
   directly either.  Instead a NAL unit sample stream format may be
   used, which provides flexibility to signal NAL unit size up to
   UINT64_MAX bytes.

5.5.2.  Single NAL unit packet

   Single NAL unit packet contains exactly one NAL unit, and consists of
   a RTP payload header and following conditional fields: 16-bit DONL
   and 16-bit v3c-tile-id.  The rest of the payload data contain the NAL
   unit payload data (excluding the NAL unit header).  Single NAL unit
   packet may contain atlas NAL units of the types defined in Table 4 of
   [ISO.IEC.23090-5].  The structure of the single NAL unit packet is
   shown below in Figure 3.
















Ilola & Kondrad          Expires 28 October 2022               [Page 15]


Internet-Draft         RTP payload format for V3C             April 2022


       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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      RTP payload header       |      DONL (conditional)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
       |      v3c-tile-id (cond)       |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
       |                                                               |
       |                        NAL unit data                          |
       |                                                               |
       |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               :...OPTIONAL RTP padding        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 3: Single NAL unit packet

   RTP payload header SHOULD be an exact copy of the NAL unit header of
   the contained NAL unit.

   A NAL unit stream composed by de-packetizing single NAL unit packets
   in RTP sequence number order MUST conform to the NAL unit decoding
   order, when DONL is not present.

   The DONL field, when present, specifies the value of the 16-bit
   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 DONL 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.

   The v3c-tile-id field, when present, specifies the 16-bit tile
   identifier for the NAL unit, as signaled in V3C atlas tile header
   defied in [ISO.IEC.23090-5].  If v3c-tile-id-pres is equal to 1 and
   RTP payload header NUT is in range 0-35, inclusive, the v3c-tile-id
   field MUST be present.  Otherwise, the v3c-tile-id field MUST NOT be
   present.

   NOTE: (informative) Only values for NAL unit type (NUT) in range
   0-35, inclusive, are allocated for atlas tile layer data, defined in
   [ISO.IEC.23090-5], which means that NAL unit types outside of the
   range are not specific to atlas tiles and SHOULD NOT contain v3c-
   tile-ids.








Ilola & Kondrad          Expires 28 October 2022               [Page 16]


Internet-Draft         RTP payload format for V3C             April 2022


5.5.3.  Aggregation packet

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

   Aggregation packets may wrap multiple NAL units belonging to the same
   access unit in a single RTP payload.  The first two bytes of the AP
   MUST contain RTP payload header.  The NAL unit type (NUT) for the NAL
   unit header contained in the RTP payload header MUST be equal to 56,
   which falls in the unspecified range of the NAL unit types defined in
   [ISO.IEC.23090-5].  AP may contain a conditional v3c-tile-id field.
   AP MUST contain two or more aggregation units.  The structure of AP
   is shown in Figure 4.

       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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  RTP payload header (NUT=56)  |      v3c-tile-id (cond)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |                  Two or more aggregation units                |
       |                                                               |
       |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               :...OPTIONAL RTP padding        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 4: Aggregation Packet (AP)

   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 NUT field MUST be equal
   to 56.  The value of NLI MUST be equal to the lowest value of NLI of
   all the aggregated NAL units.  The value of TID MUST be the lowest
   value of TID of all the aggregated NAL units.

   All ACL NAL units in an aggregation packet have the same TID value
   since they belong to the same access unit.  However, the packet may
   contain non-ACL NAL units for which the TID value in the NAL unit
   header may be different than the TID value of the ACL NAL units in
   the same AP.

   The v3c-tile-id field, when present, specifies the 16-bit tile
   identifier for all ACL NAL units in the AP.  If v3c-tile-id-pres is
   equal to 1, the v3c-tile-id field MUST be present.  Otherwise, the
   v3c-tile-id field MUST NOT be present.





Ilola & Kondrad          Expires 28 October 2022               [Page 17]


Internet-Draft         RTP payload format for V3C             April 2022


   AP MUST carry at least two aggregation units (AU) and can carry as
   many aggregation units as necessary.  However, the total amount of
   data in an AP 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.  The structure of the AU depends
   both on the presence of the decoding order number, the sequence order
   of the AU in the AP and the presence of v3c-tile-id field.  The
   structure of an AU is shown in Figure 5.

       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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  DOND (cond)  /  DONL (cond)  |      v3c-tile-id (cond)       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
       |            NALU size          |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
       |                                                               |
       |                            NAL unit                           |
       |                                                               |
       |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 5: Aggregation Unit (AU)

   If sprop-max-don-diff is greater than 0 for any of the RTP streams,
   an AU begins with the DOND / DONL field.  The first AU in the AP
   contains DONL field, which specifies the 16-bit value of the decoding
   order number of the aggregated NAL unit.  The variable DON for the
   aggregated NAL unit is derived as equal to the value of the DONL
   field.  All subsequent AUs in the AP MUST contain an (8-bit) DOND
   field, which 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.  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.

   When sprop-max-don-diff is equal to 0 for all the RTP streams, DOND /
   DONL fields MUST NOT be present in an aggregation unit.  The
   aggregation units MUST be stored in the aggregation packet so that
   the decoding order of the containing NAL units is preserved.  This
   means that the first aggregation unit in the aggregation packet
   SHOULD contain the NAL unit that SHOULD be decoded first.







Ilola & Kondrad          Expires 28 October 2022               [Page 18]


Internet-Draft         RTP payload format for V3C             April 2022


   If v3c-tile-id-pres is equal to 2 and the AU NAL unit header type is
   in range 0-35, inclusive, the 16-bit v3c-tile-id field MUST be
   present in the aggregation unit after the conditional DOND/DONL
   field.  Otherwise v3c-tile-id field MUST NOT be present in the
   aggregation unit.

   The conditional fields of the aggregation unit are followed by a
   16-bit NALU size field, which provides the size of the NAL unit (in
   bytes) in the aggregation unit.  The remainder of the data in the
   aggregation unit SHOULD contain the NAL unit (including the
   unmodified NAL unit header).

5.5.4.  Fragmentation unit

   Fragmentation Units (FUs) are introduced to enable fragmenting a
   single NAL unit into multiple RTP packets, possibly without co-
   operation or knowledge of the 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.  Aggregation packets MUST NOT be
   fragmented.  FUs MUST NOT be nested; i.e., an FU MUST NOT contain a
   subset of another FU.  The RTP header timestamp of an RTP packet
   carrying an FU is set to the NALU-time of the fragmented NAL unit.

   A FU consists of a RTP payload header with NUT equal to 58, an 8-bit
   FU header, a conditional 16-bit DONL field, a conditional 16-bit v3c-
   tile-id field and an FU payload.  The structure of an FU is
   illustrated below in Figure 6.

       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 2
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  RTP payload header (NUT=58)  |   FU header   |  DONL (cond)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
       |  DONL (cond)  |    v3c-tile-id (cond)         |               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
       |                                                               |
       |                          FU payload                           |
       |                                                               |
       |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               :...OPTIONAL RTP padding        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 6: Fragmentation Unit



Ilola & Kondrad          Expires 28 October 2022               [Page 19]


Internet-Draft         RTP payload format for V3C             April 2022


   The fields in the RTP payload header are set as follows.  The NUT
   field MUST be equal to 58.  The rest of the fields MUST be equal to
   the fragmented NAL unit.

   The FU header consists of an S bit, an E bit, and a 6-bit FUT field.
   The structure of FU header is illustrated below in Figure 7.

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

                    Figure 7: Fragmentation unit header

   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.

   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.

   The field FUT MUST be equal to the nal_unit_type field of the
   fragmented NAL unit.

   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 DONL field, when present, specifies the value of the 16-bit
   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.

   The v3c-tile-id field, when present, specifies the 16-bit tile
   identifier for the fragmented NAL unit.  If v3c-tile-id-pres is equal
   to 1, FUT is in range 0-35, and the S bit is equal to 1, the v3c-
   tile-id field MUST be present after the conditional DONL field.
   Otherwise, the v3c-tile-id field MUST NOT be present.




Ilola & Kondrad          Expires 28 October 2022               [Page 20]


Internet-Draft         RTP payload format for V3C             April 2022


   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, NLI, and TID
   fields of the RTP payload headers of the FUs and the FUT field of the
   FU header.  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.

5.6.  Decoding Order Number

   For each atlas 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 V3C atlas 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:

   *  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].

   *  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])



Ilola & Kondrad          Expires 28 October 2022               [Page 21]


Internet-Draft         RTP payload format for V3C             April 2022


      -  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:

   *  AbsDon[n] greater than AbsDon[m] indicates that NAL unit n follows
      NAL unit m in 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.

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

6.  Packetization and de-packetization rules

   The following packetization rules apply:

   *  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.

   *  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-ACL NAL units such as access unit
      delimiters, parameter sets, or SEI NAL units are typically small
      and can often be aggregated with ACL NAL units without violating
      MTU size constraints.

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

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

   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.



Ilola & Kondrad          Expires 28 October 2022               [Page 22]


Internet-Draft         RTP payload format for V3C             April 2022


   The de-packetization process is implementation dependent.  Therefore,
   the following de-packetization rules SHOULD be taken as an example.

   *  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 55,
      inclusive, may be passed to the decoder.  NAL-unit-like structures
      with NAL unit type values in the range of 55 to 63, inclusive,
      MUST NOT be passed to the decoder.

   *  When sprop-max-don-diff is equal to 0 for the received RTP stream,
      the NAL units carried in the RTP stream may be directly passed to
      the decoder in their transmission order, which is identical to
      their decoding order.

   *  When sprop-max-don-diff is greater than 0 for any of the received
      RTP streams, the received NAL units need to be arranged into
      decoding order before handing them over to the decoder.

   *  For further de-packetization examples, the reader is referred to
      Section 6 of [RFC7798].

7.  Payload Examples

7.1.  General

   Examples describing the different payload formats is provided.

7.2.  V3C fragmentation unit

   This example illustrates how fragmetation unit may be used to divide
   one NAL unit into to RTP packets.  The Figure 8 illustrates the
   structure of the first packet with the first part of the fragmented
   NAL unit.












Ilola & Kondrad          Expires 28 October 2022               [Page 23]


Internet-Draft         RTP payload format for V3C             April 2022


       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 payload header (NUT=58)  |   FU header   |               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
       |                                                               |
       |                          FU payload                           |
       |                                                               |
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 8: First packet of fragmented NAL unit

   The Figure 9 illustrates the structure of the second packet with the
   rest of the fragmented NAL unit.

       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 payload header (NUT=58)  |   FU header   |               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
       |                                                               |
       |                          FU payload                           |
       |                                                               |
       |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               :...OPTIONAL RTP padding        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 9: Second packet of fragmented NAL unit



Ilola & Kondrad          Expires 28 October 2022               [Page 24]


Internet-Draft         RTP payload format for V3C             April 2022


8.  Payload Format Parameters

   This section specifies the parameters that MAY be used to select
   optional features of the payload format and certain features or
   properties of the bitstream or the RTP stream.  The parameters are
   specified here as part of the media type registration for the V3C
   codec.  A mapping of the parameters into the Session Description
   Protocol (SDP) [RFC8866] is also provided for applications that use
   SDP.  Equivalent parameters could be defined elsewhere for use with
   control protocols that do not use SDP.

8.1.  Media Type Definition

   Type name: application

   Subtype name: v3c

   Optional parameters: v3c-unit-header, v3c-unit-type, v3c-vps-id, v3c-
   atlas-id, v3c-attr-idx, v3c-attr-part-idx, v3c-map-idx, v3c-aux-
   video-flag, v3c-parameter-set, v3c-tile-id, v3c-tile-id-pres, v3c-
   atlas-data, v3c-common-atlas-data, v3c-sei, v3c-ptl-level-idc, v3c-
   ptl-tier-flag, v3c-ptl-codec-idc, v3c-ptl-toolset-idc, v3c-ptl-rec-
   idc, tx-mode and sprop-max-don-diff.

       v3c-unit-header:

   provides a V3C unit header bytes defined in [ISO.IEC.23090-5].  The
   value contains base16 [RFC4648] (hexadecimal) representation of the 4
   bytes of V3C unit header.

       v3c-unit-type:

   v3c-unit-type provides a V3C unit type value corresponding to
   vuh_unit_type defined in [ISO.IEC.23090-5], i.e. defines V3C sub-
   bitstream type.

       v3c-vps-id:

   v3c-vps-id provides a value corresponding to vuh_v3c_parameter_set_id
   defined in [ISO.IEC.23090-5].

       v3c-atlas-id:

   v3c-atlas-id provides a value corresponding to vuh_atlas_id defined
   in [ISO.IEC.23090-5].

       v3c-attr-idx:




Ilola & Kondrad          Expires 28 October 2022               [Page 25]


Internet-Draft         RTP payload format for V3C             April 2022


   v3c-attr-idx provides a value corresponding to vuh_attribute_index
   defined in [ISO.IEC.23090-5].

       v3c-attr-part-idx:

   v3c-attr-part-idx provides a value corresponding to
   vuh_attribute_partition_index defined in [ISO.IEC.23090-5].

       v3c-map-idx:

   v3c-map-idx provides a value corresponding to vuh_map_index defined
   in [ISO.IEC.23090-5].

       v3c-aux-video-flag:

   v3c-aux-video-flag provides a value corresponding to
   vuh_auxiliary_video_flag defined in [ISO.IEC.23090-5].

       v3c-parameter-set:

   v3c-parameter-set provides V3C parameter set bytes as defined in
   [ISO.IEC.23090-5].  The value contains base16 [RFC4648] (hexadecimal)
   representation of the V3C parameter set bytes.

       v3c-tile-id:

   v3c-tile-id indicates that the RTP stream contains only portion of
   the tiles in the atlas. v3c-tile-id is a comma-spearated (',') list
   of integer values, which indicate the v3c-tile-ids that are present
   in the RTP stream.

       v3c-tile-id-pres:

   v3c-tile-id-pres indicates that the RTP packets contain v3c-tile-id
   field.

       v3c-atlas-data:

   v3c-atlas-data may be used to convey any atlas data NAL units of the
   V3C atlas sub bitstream for out-of-band transmission.  The value is a
   comma-separated (',') list of encoded representations of the atlas
   NAL units as specified in [ISO.IEC.23090-5].  The NAL units SHOULD be
   encoded as base16 [RFC4648] (hexadecimal) representations.

       v3c-common-atlas-data:






Ilola & Kondrad          Expires 28 October 2022               [Page 26]


Internet-Draft         RTP payload format for V3C             April 2022


   v3c-common-atlas-data may be used to convey common atlas data NAL
   units of the V3C common atlas sub bitstream for out-of-band
   transmission.  The value is a comma-separated (',') list of encoded
   representations of the common atlas NAL units (i.e.  NAL_CASPS and
   NAL_CAF_IDR) as specified in [ISO.IEC.23090-5].  The NAL units SHOULD
   be encoded as base16 [RFC4648] (hexadecimal) representations.

       v3c-sei:

   v3c-sei may be used to convey SEI NAL units of V3C atlas and common
   atlas sub bitstreams for out-of-band transmission.  The value is a
   comma-separated (',') list of encoded representations of SEI NAL
   units (i.e.  NAL_PREFIX_NSEI and NAL_SUFFIX_NSEI, NAL_PREFIX_ESEI,
   NAL_SUFFIX_ESEI) as specified in [ISO.IEC.23090-5].  The SEI NAL
   units SHOULD be encoded as base16 [RFC4648] (hexadecimal)
   representations.

       v3c-ptl-level-idc:

   v3c-ptl-level-idc provides a value corresponding to ptl_level_idc
   defined in [ISO.IEC.23090-5].

       v3c-ptl-tier-flag:

   v3c-ptl-tier-flag provides a value corresponding to ptl_tier_flag
   defined in [ISO.IEC.23090-5].

       v3c-ptl-codec-idc:

   v3c-ptl-codec-idc provides a value corresponding to
   ptl_profile_codec_group_idc defined in [ISO.IEC.23090-5].

       v3c-ptl-toolset-idc:

   v3c-ptl-toolset-idc provides a value corresponding to
   ptl_profile_toolset_idc defined in [ISO.IEC.23090-5].

       v3c-ptl-rec-idc:

   v3c-ptl-rec-idc provides a value corresponding to
   ptl_profile_reconstruction_idc defined in [ISO.IEC.23090-5].

       tx-mode:

   This parameter indicates whether the transmission mode is SRST, MRST,
   or MRMT.





Ilola & Kondrad          Expires 28 October 2022               [Page 27]


Internet-Draft         RTP payload format for V3C             April 2022


   The value of tx-mode MUST be equal to "SRST", "MRST" or "MRMT".  When
   not present, the value of tx-mode is inferred to be equal to "SRST".

   If the value is equal to "MRST", MRST MUST be in use.  Otherwise, if
   the value is equal to "MRMT", MRMT MUST be in use.  Otherwise (the
   value is equal to "SRST"), SRST MUST be in use.

   The value of tx-mode MUST be equal to "MRST" for all RTP streams in
   an MRST.

   The value of tx-mode MUST be equal to "MRMT" for all RTP streams in
   an MRMT.

       sprop-max-don-diff:

   If the transmission order of NAL units in the RTP stream(s) is the
   same as the decoding and NAL unit output order, this parameter must
   be equal to 0.

   Otherwise, if the decoding order of the NAL units of the RTP
   stream(s) is the same as the NAL unit transmission order but not the
   same as NAL unit output order, the value of this parameter MUST be
   equal to 1.

   Otherwise, this parameter specifies the maximum absolute difference
   between the decoding order number (i.e., AbsDon) values of any two
   NAL units naluA and naluB, where naluA follows naluB in decoding
   order and precedes naluB in transmission order.

   The value of sprop-max-don-diff MUST be an integer in the range of 0
   to 32767, inclusive.

   When not present, the value of sprop-max-don-diff is inferred to be
   equal to 0.

   Encoding considerations:

   This media type is framed and binary; see Section 4.8 in [RFC6838].

   Security considerations:

   Please see Section 12.

   Interoperability considerations: N/A

   Published specification:

   Applications that use this media type: N/A



Ilola & Kondrad          Expires 28 October 2022               [Page 28]


Internet-Draft         RTP payload format for V3C             April 2022


   Additional information: N/A

   Person & email address to contact for further information:

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: See Authors' Addresses section of this memo.

   Change controller: IETF Payload working group delegated from the
   IESG.

   Provisional registration? (standards tree only): No

9.  Congestion Control Considerations

   This section is to describe the possibility to vary the bitrate as a
   response to congestion.  Below is also a proposal for an initial text
   that reference RTP and profiles definition of congestion control.

   Congestion control for RTP SHALL be used in accordance with
   [RFC3550], and with any applicable RTP profile: e.g., [RFC3551].  An
   additional requirement if best-effort service is being used is users
   of this payload format MUST monitor packet loss to ensure that the
   packet loss rate is within acceptable parameters.

   Circuit Breakers [RFC8083] is an update to RTP [RFC3550] that defines
   criteria for when one is required to stop sending RTP Packet Streams.
   The circuit breakers is to be implemented and followed.

10.  Session Description Protocol

   The mapping of above defined payload format media type is mapped to
   fields in the Session Description Protocol (SDP) according to
   [RFC8866].

10.1.  Mapping of payload type parameters to SDP

10.1.1.  For V3C atlas components

   *  The media name in the "m=" line of SDP MUST be application.

   *  The encoding name in the "a=rtpmap" line of SDP must be v3c

   *  The clock rate in the "a=rtpmap" line MUST be 90000.





Ilola & Kondrad          Expires 28 October 2022               [Page 29]


Internet-Draft         RTP payload format for V3C             April 2022


   *  The OPTIONAL parameters v3c-unit-header, v3c-unit-type, v3c-vps-
      id, v3c-atlas-id, v3c-attr-idx, v3c-attr-part-idx, v3c-map-idx,
      v3c-aux-video-flag, sprop-max-don-diff, v3c-parameter-set, v3c-
      atlas-data, v3c-common-atlas-data, v3c-sei, v3c-tile-id, v3c-tile-
      id-pres, v3c-ptl-level-idc, v3c-ptl-tier-flag, v3c-ptl-codec-idc,
      v3c-ptl-toolset-idc, v3c-ptl-rec-idc, when present, MUST be
      included in the "a=fmtp" line of SDP.  This parameter is expressed
      as a media type string, in the form of a semicolon-separated list
      of parameter=value pairs.

   An example of media representation in SDP is as follows:

       m=application 49170 RTP/AVP 98
       a=rtpmap:98 v3c/90000
       a=fmtp:98 v3c-unit-header=08000000; // V3C_AD
                 v3c-ptl-tier-flag=1

10.1.2.  For V3C video components

   *  The media name in the "m=" line of SDP MUST be video.

   *  The encoding name in the "a=rtpmap" line of SDP can be any video
      subtype, e.g. avc, hevc, vvc etc.

   *  The clock rate in the "a=rtpmap" line MUST be 90000.

   *  The OPTIONAL parameters v3c-unit-header, v3c-unit-type, v3c-vps-
      id, v3c-atlas-id, v3c-attr-idx, v3c-attr-part-idx, v3c-map-idx,
      v3c-aux-video-flag, sprop-max-don-diff, v3c-parameter-set, v3c-
      atlas-data, v3c-common-atlas-data, v3c-sei, v3c-tile-id, v3c-tile-
      id-pres, v3c-ptl-level-idc, v3c-ptl-tier-flag, v3c-ptl-codec-idc,
      v3c-ptl-toolset-idc, v3c-ptl-rec-idc, when present, MUST be
      included in the "a=fmtp" line of SDP.  This parameter is expressed
      as a media type string, in the form of a semicolon-separated list
      of parameter=value pairs.

   *  The OPTIONAL parameters may include any optional parameters from
      the respective video payload specifications.

   An example of media representation corresponding to occupancy
   component in SDP is as follows:

       m=video 49170 RTP/AVP 99
       a=rtpmap:99 H265/90000
       a=fmtp:99 sprop-max-don-diff=0;
                 v3c-unit-header=10000000





Ilola & Kondrad          Expires 28 October 2022               [Page 30]


Internet-Draft         RTP payload format for V3C             April 2022


   When v3c-unit-header or v3c-unit-type indicate V3C unit type V3C_PVD,
   v3c-parameter-set, v3c-atlas-data or v3c-common-atlas-data may be
   signaled along the video stream.  When v3c-parameter-set, v3c-atlas-
   data or v3c-common-atlas-data are present it indicates that the
   provided data is static for the whole duration of the stream.

   When v3c-parameter-set, v3c-atlas-data or v3c-common-atlas-data are
   signaled along the video stream it is expected the respective v3c-
   parameter-set, v3c-atlas-data or v3c-common-atlas-data remain static
   for the duration of the stream.

   An example of media representation in SDP is as follows:

       m=video 49170 RTP/AVP 99
       a=rtpmap:99 H265/90000
       a=fmtp:99 v3c-unit-header=28000000;
                 v3c-parameter-set=F6F0093992;
                 v3c-atlas-data=ABCA,5D5A,68

10.2.  Grouping Framework

   Different V3C components can be represented by their own respective
   RTP streams.  A grouping tool, as defined in [RFC5888], may be
   extended to support V3C grouping.

   Group attribute with V3C type is provided to allow application to
   identifity "m" lines that belong to the same V3C bitstream.  Grouping
   type V3C MUST be used with the group attribute.  The tokens that
   follow are mapped to 'mid'-values of individual media lines in the
   SDP.

       a=group:V3C <tokens> <v3c specific session-level parameters>

   The V3C grouping type attribute related v3c-specific session level
   parameters can include the following optional information:

       v3c-parameter-set=<value>
       v3c-atlas-data=<value>
       v3c-common-atlas-data=<value>
       v3c-sei=<value>

   When signaled as a session level parameter, the data is considered to
   be static for the duration of the stream.

   The following example shows an SDP including four media lines, three
   describing V3C video components and one V3C atlas component.  All the
   media lines are grouped under one V3C group which provides the V3C
   parameter set.



Ilola & Kondrad          Expires 28 October 2022               [Page 31]


Internet-Draft         RTP payload format for V3C             April 2022


       ...
       a=group:V3C 1 2 3 4 v3c-parameter-set=AF6F00939921878
       m=video 40000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-header=10000000 // occupancy
       a=mid:1
       m=video 40002 RTP/AVP 97
       a=rtpmap:97 H264/90000
       a=fmtp:97 v3c-unit-header=18000000 // geometry
       a=mid:2
       m=video 40004 RTP/AVP 98
       a=rtpmap:98 H264/90000
       a=fmtp:98 v3c-unit-header=20000000 // attribute
       a=mid:3
       m=video 40008 RTP/AVP 100
       a=rtpmap:100 v3c/90000
       a=fmtp:100 v3c-unit-header=08000000; // atlas
       a=mid:4

   V3C group attribute type can be used as follows to indicate different
   V3C components and associate static atlas data with them.

       ...
       a=group:v3c 1 2 3 v3c-parameter-set=AF6F00939921878;
                           v3c-atlas-data=ABCA,5D5D,68
       m=video 40000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-header=10000000; // occupancy
       a=mid:1
       m=video 40002 RTP/AVP 97
       a=rtpmap:97 H264/90000
       a=fmtp:96 v3c-unit-header=18000000; // geometry
       a=mid:2
       m=video 40004 RTP/AVP 98
       a=rtpmap:98 H264/90000
       a=fmtp:96 v3c-unit-header=20000000; // attribute
       a=mid:3

   The following example describes how every v3c video component is
   packed in to a single stream and associated with static atlas data.

       ...
       m=video 40000 RTP/AVP 96
       a=rtpmap:96 H265/90000
       a=fmtp:96 v3c-unit-header=28000000; // packed video
                 v3c-parameter-set=AF6F00939921878;
                 v3c-atlas-data=ABCA,5D5D,68
       a=mid:1



Ilola & Kondrad          Expires 28 October 2022               [Page 32]


Internet-Draft         RTP payload format for V3C             April 2022


   The example below describes how content with two atlases can be
   signaled as separate streams.

       ...
       a=group:V3C 1 2 3 4 5 6 7 8 v3c-parameter-set=AF6F00939921878;
                                   v3c-common-atlas-data=AFFA,0110;
       m=video 40000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-header=10000000 // occupancy, atlas 0
       a=mid:1
       m=video 40002 RTP/AVP 97
       a=rtpmap:97 H264/90000
       a=fmtp:97 v3c-unit-header=18000000 // geometry, atlas 0
       a=mid:2
       m=video 40004 RTP/AVP 98
       a=rtpmap:98 H264/90000
       a=fmtp:98 v3c-unit-header=20000000 // attribute, atlas 0
       a=mid:3
       m=video 40008 RTP/AVP 100
       a=rtpmap:100 v3c/90000
       a=fmtp:100 v3c-unit-header=08000000; // atlas 0
       a=mid:4
       m=video 40010 RTP/AVP 101
       a=rtpmap:101 H264/90000
       a=fmtp:101 v3c-unit-header=10020000 // occupancy, atlas 1
       a=mid:5
       m=video 40012 RTP/AVP 102
       a=rtpmap:102 H264/90000
       a=fmtp:102 v3c-unit-header=18020000 // geometry, atlas 1
       a=mid:6
       m=video 40014 RTP/AVP 103
       a=rtpmap:103 H264/90000
       a=fmtp:103 v3c-unit-header=20020000 // attribute, atlas 1
       a=mid:7
       m=video 40018 RTP/AVP 104
       a=rtpmap:104 v3c/90000
       a=fmtp:104 v3c-unit-header=08020000; // V3C_AD, atlas 1
       a=mid:8

10.3.  Offer/Answer Considerations

   An example of offer which only sends V3C content.  The following
   example contains video components at three different versions.








Ilola & Kondrad          Expires 28 October 2022               [Page 33]


Internet-Draft         RTP payload format for V3C             April 2022


       ...
       a=group:v3c 1 2 3 4 v3c-ptl-level-idc=10;
                           v3c-parameter-set=AF6F00939921878
       m=video 40000 RTP/AVP 96 97 98
       a=rtpmap:96 H264/90000
       a=rtpmap:97 H265/90000
       a=rtpmap:98 H266/90000
       a=fmtp:96 v3c-unit-type=2;v3c-vps-id=0;v3c-atlas-id=0
       a=fmtp:97 v3c-unit-type=2;v3c-vps-id=0;v3c-atlas-id=0
       a=fmtp:98 v3c-unit-type=2;v3c-vps-id=0;v3c-atlas-id=0
       a=sendonly
       a=mid:1
       m=video 40002 RTP/AVP 96 97 98
       a=rtpmap:96 H264/90000
       a=rtpmap:97 H265/90000
       a=rtpmap:98 H266/90000
       a=fmtp:96 v3c-unit-type=3;v3c-vps-id=0;v3c-atlas-id=0;
       a=fmtp:97 v3c-unit-type=3;v3c-vps-id=0;v3c-atlas-id=0;
       a=fmtp:98 v3c-unit-type=3;v3c-vps-id=0;v3c-atlas-id=0;
       a=mid:2
       a=sendonly
       m=video 40004 RTP/AVP 96 97 98
       a=rtpmap:96 H264/90000
       a=rtpmap:97 H265/90000
       a=rtpmap:98 H266/90000
       a=fmtp:96 v3c-unit-type=4;v3c-vps-id=0;v3c-atlas-id=0
       a=fmtp:97 v3c-unit-type=4;v3c-vps-id=0;v3c-atlas-id=0
       a=fmtp:98 v3c-unit-type=4;v3c-vps-id=0;v3c-atlas-id=0
       a=mid:3
       a=sendonly
       m=video 40006 RTP/AVP 100
       a=rtpmap:100 v3c/90000
       a=fmtp:100 v3c-unit-type=1;v3c-vps-id=0;v3c-atlas-id=0
       a=mid:4
       a=sendonly

   An example of answer which only receives V3C data with the selected
   versions.













Ilola & Kondrad          Expires 28 October 2022               [Page 34]


Internet-Draft         RTP payload format for V3C             April 2022


       ...
       a=group:v3c 1 2 3 4
       m=video 50000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=recvonly
       m=video 50002 RTP/AVP 97
       a=rtpmap:97 H265/90000
       a=recvonly
       m=video 50004 RTP/AVP 98
       a=rtpmap:98 H266/90000
       a=recvonly
       m=video 50006 RTP/AVP 96
       a=rtpmap:96 v3c/90000
       a=recvonly

   An example offer, which allows bundling different V3C components on
   one stream, based on [RFC9143].

       ...
       a=group:BUNDLE 1 2 3 4
       a=group:v3c 1 2 3 4 v3c-parameter-set=AF6F00939921878
       m=video 40000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-type=2;v3c-vps-id=0;v3c-atlas-id=0
       a=mid:1
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 40002 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-type=3;v3c-vps-id=0;v3c-atlas-id=0;
       a=mid:2
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 40004 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=fmtp:96 v3c-unit-type=4;v3c-vps-id=0;v3c-atlas-id=0
       a=mid:3
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 40006 RTP/AVP 97
       a=rtpmap:97 v3c/90000
       a=fmtp:97 v3c-unit-type=1;v3c-vps-id=0;v3c-atlas-id=0
       a=mid:4
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid

   An example answer, which accepts bundling of different V3C
   components.







Ilola & Kondrad          Expires 28 October 2022               [Page 35]


Internet-Draft         RTP payload format for V3C             April 2022


       a=group:BUNDLE 1 2 3 4
       a=group:v3c 1 2 3 4
       m=video 50000 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=mid:1
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 0 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=bundle-only
       a=mid:2
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 0 RTP/AVP 96
       a=rtpmap:96 H264/90000
       a=bundle-only
       a=mid:3
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid
       m=video 0 RTP/AVP 97
       a=rtpmap:97 v3c/90000
       a=bundle-only
       a=mid:4
       a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid

10.4.  Declarative SDP Considerations

   Placeholder

11.  IANA Considerations

   Placeholder

12.  Security Considerations

   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 Protocol 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 Security Considerations
   section discusses the security impacting properties of the payload
   format itself.



Ilola & Kondrad          Expires 28 October 2022               [Page 36]


Internet-Draft         RTP payload format for V3C             April 2022


   This RTP payload format and its media decoder do not exhibit any
   significant non-uniformity in the receiver-side computational
   complexity for packet processing, and thus are unlikely to pose a
   denial-of-service threat due to the receipt of pathological data.
   Nor does the RTP payload format contain any active content.

13.  References

13.1.  Normative References

   [ISO.IEC.23090-12]
              ISO/IEC, "Information technology --- Coded representation
              of immersive media --- Part 12: MPEG Immersive video
              (MIV)", ISO/IEC 23090-12, 2022,
              <https://www.iso.org/standard/79113.html>.

   [ISO.IEC.23090-5]
              ISO/IEC, "Information technology --- Coded representation
              of immersive media --- Part 5: Visual volumetric video-
              based coding (V3C) and video-based point cloud compression
              (V-PCC)", ISO/IEC 23090-5, 2021,
              <https://www.iso.org/standard/73025.html>.

   [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>.

   [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>.



Ilola & Kondrad          Expires 28 October 2022               [Page 37]


Internet-Draft         RTP payload format for V3C             April 2022


   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/info/rfc4648>.

   [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>.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
              Protocol (SDP) Grouping Framework", RFC 5888,
              DOI 10.17487/RFC5888, June 2010,
              <https://www.rfc-editor.org/info/rfc5888>.

   [RFC6184]  Wang, Y.-K., 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.-K., 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>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC7798]  Wang, Y.-K., Sanchez, Y., Schierl, T., Wenger, S., and M.
              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>.

   [RFC8083]  Perkins, C. and V. Singh, "Multimedia Congestion Control:
              Circuit Breakers for Unicast RTP Sessions", RFC 8083,
              DOI 10.17487/RFC8083, March 2017,
              <https://www.rfc-editor.org/info/rfc8083>.

   [RFC8866]  Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
              Session Description Protocol", RFC 8866,
              DOI 10.17487/RFC8866, January 2021,
              <https://www.rfc-editor.org/info/rfc8866>.








Ilola & Kondrad          Expires 28 October 2022               [Page 38]


Internet-Draft         RTP payload format for V3C             April 2022


   [RFC9143]  Holmberg, C., Alvestrand, H., and C. Jennings,
              "Negotiating Media Multiplexing Using the Session
              Description Protocol (SDP)", RFC 9143,
              DOI 10.17487/RFC9143, February 2022,
              <https://www.rfc-editor.org/info/rfc9143>.

13.2.  Informative References

   [ISO.IEC.14496-10]
              ISO/IEC, "Information technology - Coding of audio-visual
              objects - Part 10: Advanced video coding", ISO/
              IEC 14496-10, 2020,
              <https://www.iso.org/standard/75400.html>.

   [ISO.IEC.14496-12]
              ISO/IEC, "Information technology --- Coding of audio-
              visual objects --- Part 12: ISO base media file format",
              ISO/IEC 14496-12, 2020,
              <https://www.iso.org/standard/74428.html>.

   [ISO.IEC.23008-2]
              ISO/IEC, "Information technology --- High efficiency
              coding and media delivery in heterogeneous environments
              --- Part 2: High efficiency video coding", ISO/
              IEC 23008-2, 2020,
              <https://www.iso.org/standard/75484.html>.

   [ISO.IEC.23090-10]
              ISO/IEC, "Information technology --- Coded representation
              of immersive media --- Part 10: Carriage of visual
              volumetric video-based coding data", ISO/IEC FDIS
              23090-10, 2022, <https://www.iso.org/standard/78991.html>.

   [ISO.IEC.23090-3]
              ISO/IEC, "Information technology --- Coded representation
              of immersive media --- Part 3: Versatile video coding",
              ISO/IEC 23090-3, 2021,
              <https://www.iso.org/standard/73022.html>.

   [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>.




Ilola & Kondrad          Expires 28 October 2022               [Page 39]


Internet-Draft         RTP payload format for V3C             April 2022


Authors' Addresses

   Lauri Ilola
   Nokia Technologies
   Werinherstrasse 91
   D-81541 Munich
   Germany
   Email: lauri.ilola@nokia.com


   Lukasz Kondrad
   Nokia Technologies
   Werinherstrasse 91
   D-81541 Munich
   Germany
   Email: lukasz.kondrad@nokia.com



































Ilola & Kondrad          Expires 28 October 2022               [Page 40]