avtcore L. Ilola Internet-Draft L. Kondrad Intended status: Standards Track Nokia Technologies Expires: 1 October 2023 30 March 2023 RTP Payload Format for Visual Volumetric Video-based Coding (V3C) draft-ietf-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 V3C 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 content. 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 1 October 2023. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Ilola & Kondrad Expires 1 October 2023 [Page 1] Internet-Draft RTP payload format for V3C March 2023 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 3.2. 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 . . . . . . . . . . . . . . . . . . . 11 4.4. Systems and transport interfaces . . . . . . . . . . . . 12 5. V3C Atlas RTP payload format . . . . . . . . . . . . . . . . 12 5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.2. RTP Header . . . . . . . . . . . . . . . . . . . . . . . 12 5.3. RTP payload header . . . . . . . . . . . . . . . . . . . 14 5.4. Transmission modes . . . . . . . . . . . . . . . . . . . 15 5.5. Payload structures . . . . . . . . . . . . . . . . . . . 15 5.5.1. General . . . . . . . . . . . . . . . . . . . . . . . 16 5.5.2. Single NAL unit packet . . . . . . . . . . . . . . . 16 5.5.3. Aggregation packet . . . . . . . . . . . . . . . . . 18 5.5.4. Fragmentation unit . . . . . . . . . . . . . . . . . 20 5.6. Decoding Order Number . . . . . . . . . . . . . . . . . . 22 6. Packetization and de-packetization rules . . . . . . . . . . 23 7. Payload Examples . . . . . . . . . . . . . . . . . . . . . . 24 7.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 24 7.2. V3C fragmentation unit . . . . . . . . . . . . . . . . . 24 8. Payload Format Parameters . . . . . . . . . . . . . . . . . . 26 8.1. Media Type Definition . . . . . . . . . . . . . . . . . . 26 9. Congestion Control Considerations . . . . . . . . . . . . . . 30 10. Session Description Protocol . . . . . . . . . . . . . . . . 30 10.1. Mapping of payload type parameters to SDP . . . . . . . 30 10.1.1. For V3C atlas components . . . . . . . . . . . . . . 30 10.1.2. For V3C video components . . . . . . . . . . . . . . 31 10.2. Grouping Framework . . . . . . . . . . . . . . . . . . . 32 Ilola & Kondrad Expires 1 October 2023 [Page 2] Internet-Draft RTP payload format for V3C March 2023 10.3. Offer/Answer Considerations . . . . . . . . . . . . . . 34 10.4. Declarative SDP Considerations . . . . . . . . . . . . . 37 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37 12. Security Considerations . . . . . . . . . . . . . . . . . . . 37 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 13.1. Normative References . . . . . . . . . . . . . . . . . . 38 13.2. Informative References . . . . . . . . . . . . . . . . . 40 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 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 (H.264) [ISO.IEC.14496-10], ISO/IEC International Standard 23008-2 (H.265) [ISO.IEC.23008-2] or ISO/IEC International Standard 23090-3 (H.266) [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) design, familiar 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 the other 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 1 October 2023 [Page 3] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 4] Internet-Draft RTP payload format for V3C March 2023 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 a 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 1 October 2023 [Page 5] Internet-Draft RTP payload format for V3C March 2023 volumetric frame: set of 3D points specified by their cartesian coordinates and zero or more corresponding sets of attributes at a particular time instance. 3.2. 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 1 October 2023 [Page 6] Internet-Draft RTP payload format for V3C March 2023 4.1. Overview of the V3C codec ISO/IEC International Standards 23090-5 [ISO.IEC.23090-5] defines encoding and decoding processes of volumetric video which leverages 2D video coding technologies. 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 documenting such conversions and transformations. The associated data, also known as atlas data, is necessary to define how to reproject the 2D representations back into 3D volumetric frame. 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 additional properties for the voxels, e.g., colour 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 the 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 decodable. 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 1 October 2023 [Page 7] Internet-Draft RTP payload format for V3C March 2023 4.2. V3C parameter set While this memo intends to describe encapsulation of V3C atlas data, aspects related to signalling of V3C parameter set need to be considered. V3C parameter set is signalled 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 signalled as part of session description protocol, see Section 10. Generally, it is useful to signal V3C parameter set out-of-band, because it describes what overall resources are needed to decode and reconstruct the associated V3C bitstream. Signalling it dynamically as part of an RTP stream might result in undefined behaviour when receiver does not have the required capabilities to decode the received video component sub-bitstreams or when reconstruction process relies on information that the receiver does not support. 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, or V3C_CAD in case of common atlas data, 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. V3C video components can be further separated by other values in the V3C unit header such as 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., colour. 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 1 October 2023 [Page 8] Internet-Draft RTP payload format for V3C March 2023 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]. As a convenience, the mapping table from vuh_unit_type values to semantics is copied below in Table 1. Ilola & Kondrad Expires 1 October 2023 [Page 9] Internet-Draft RTP payload format for V3C March 2023 +===============+============+===========+======================+ | vuh_unit_type | Identifier | V3C unit | Description | | | | type | | +===============+============+===========+======================+ | 0 | V3C_VPS | V3C | V3C level parameters | | | | parameter | | | | | set | | +---------------+------------+-----------+----------------------+ | 1 | V3C_AD | Atlas | Atlas information | | | | data | | +---------------+------------+-----------+----------------------+ | 2 | V3C_OVD | Occupancy | Occupancy | | | | video | information | | | | data | | +---------------+------------+-----------+----------------------+ | 3 | V3C_GVD | Geometry | Geometry information | | | | video | | | | | data | | +---------------+------------+-----------+----------------------+ | 4 | V3C_AVD | Attribute | Attribute | | | | video | information | | | | data | | +---------------+------------+-----------+----------------------+ | 5 | V3C_PVD | Packed | Packing information | | | | video | | | | | data | | +---------------+------------+-----------+----------------------+ | 6 | V3C_CAD | Common | Information that is | | | | atlas | common for atlases | | | | data | in a CVS. Specified | | | | | in ISO/IEC 23090-12 | +---------------+------------+-----------+----------------------+ | 7...31 | V3C_RSVD | Reserved | - | +---------------+------------+-----------+----------------------+ Table 1: V3C unit type semantics 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 1 October 2023 [Page 10] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 11] Internet-Draft RTP payload format for V3C March 2023 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 designing 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 definitions. 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 1 October 2023 [Page 12] Internet-Draft RTP payload format for V3C March 2023 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 MUST 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 1 October 2023 [Page 13] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 14] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 15] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 16] Internet-Draft RTP payload format for V3C March 2023 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 signalled 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 1 October 2023 [Page 17] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 18] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 19] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 20] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 21] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 22] Internet-Draft RTP payload format for V3C March 2023 - 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 1 October 2023 [Page 23] Internet-Draft RTP payload format for V3C March 2023 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 fragmentation 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 1 October 2023 [Page 24] Internet-Draft RTP payload format for V3C March 2023 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) |1|0| FUT | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | 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) |0|1| FUT | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | | FU payload | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | :...OPTIONAL RTP padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9: Second packet of fragmented NAL unit Ilola & Kondrad Expires 1 October 2023 [Page 25] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 26] Internet-Draft RTP payload format for V3C March 2023 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-separated (',') 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 1 October 2023 [Page 27] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 28] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 29] Internet-Draft RTP payload format for V3C March 2023 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 1 October 2023 [Page 30] Internet-Draft RTP payload format for V3C March 2023 * 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 1 October 2023 [Page 31] Internet-Draft RTP payload format for V3C March 2023 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 signalled 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 signalled 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 identify "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 The V3C grouping type attribute related v3c-specific session level parameters can include the following optional information: v3c-parameter-set= v3c-atlas-data= v3c-common-atlas-data= v3c-sei= When signalled 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 1 October 2023 [Page 32] Internet-Draft RTP payload format for V3C March 2023 ... 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=application 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 into 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 1 October 2023 [Page 33] Internet-Draft RTP payload format for V3C March 2023 The example below describes how content with two atlases can be signalled 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=application 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=application 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 1 October 2023 [Page 34] Internet-Draft RTP payload format for V3C March 2023 ... 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=application 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 1 October 2023 [Page 35] Internet-Draft RTP payload format for V3C March 2023 ... 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=application 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=application 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 1 October 2023 [Page 36] Internet-Draft RTP payload format for V3C March 2023 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=application 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 1 October 2023 [Page 37] Internet-Draft RTP payload format for V3C March 2023 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, . [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, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [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, . [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, . [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, . Ilola & Kondrad Expires 1 October 2023 [Page 38] Internet-Draft RTP payload format for V3C March 2023 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, . [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, . [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description Protocol (SDP) Grouping Framework", RFC 5888, DOI 10.17487/RFC5888, June 2010, . [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, . [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, . [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, . [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, . [RFC8083] Perkins, C. and V. Singh, "Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions", RFC 8083, DOI 10.17487/RFC8083, March 2017, . [RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP: Session Description Protocol", RFC 8866, DOI 10.17487/RFC8866, January 2021, . Ilola & Kondrad Expires 1 October 2023 [Page 39] Internet-Draft RTP payload format for V3C March 2023 [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, . 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, . [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, . [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, . [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, . [ISO.IEC.23090-3] ISO/IEC, "Information technology --- Coded representation of immersive media --- Part 3: Versatile video coding", ISO/IEC 23090-3, 2021, . [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014, . [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, . Ilola & Kondrad Expires 1 October 2023 [Page 40] Internet-Draft RTP payload format for V3C March 2023 Authors' Addresses Lauri Ilola Nokia Technologies Hatanpaeaen valtatie 30 FI-33100 Tampere Finland Email: lauri.ilola@nokia.com Lukasz Kondrad Nokia Technologies Werinherstrasse 91 D-81541 Munich Germany Email: lukasz.kondrad@nokia.com Ilola & Kondrad Expires 1 October 2023 [Page 41]