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Versions: (draft-lugan-payload-rtp-jpegxs) 00 01 02 03 04 05

avtcore                                                         S. Lugan
Internet-Draft                                               A. Descampe
Intended status: Standards Track                               C. Damman
Expires: October 10, 2020                                        intoPIX
                                                              T. Richter
                                                                     IIS
                                                              A. Willeme
                                                              UCL/ICTEAM
                                                           April 8, 2020


             RTP Payload Format for ISO/IEC 21122 (JPEG XS)
                    draft-ietf-payload-rtp-jpegxs-03

Abstract

   This document specifies a Real-Time Transport Protocol (RTP) payload
   format to be used for transporting JPEG XS (ISO/IEC 21122) encoded
   video.  JPEG XS is a low-latency, lightweight image coding system.
   Compared to an uncompressed video use case, it allows higher
   resolutions and frame rates, while offering visually lossless
   quality, reduced power consumption, and end-to-end latency confined
   to a fraction of a frame.

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 October 10, 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions, Definitions, and Abbreviations . . . . . . . . .   3
   3.  Media Format Description  . . . . . . . . . . . . . . . . . .   4
     3.1.  Image Data Structures . . . . . . . . . . . . . . . . . .   4
     3.2.  Codestream  . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Video support box and colour specification box  . . . . .   5
     3.4.  JPEG XS Frame . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Payload Format  . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  RTP packetization . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Payload Header  . . . . . . . . . . . . . . . . . . . . .   8
     4.3.  Payload Data  . . . . . . . . . . . . . . . . . . . . . .  11
     4.4.  Traffic Shaping and Delivery Timing . . . . . . . . . . .  14
   5.  Congestion Control Considerations . . . . . . . . . . . . . .  14
   6.  Payload Format Parameters . . . . . . . . . . . . . . . . . .  14
     6.1.  Media Type Definition . . . . . . . . . . . . . . . . . .  14
     6.2.  Mapping to SDP  . . . . . . . . . . . . . . . . . . . . .  17
       6.2.1.  General . . . . . . . . . . . . . . . . . . . . . . .  17
       6.2.2.  Media type and subtype  . . . . . . . . . . . . . . .  18
       6.2.3.  Traffic shaping . . . . . . . . . . . . . . . . . . .  18
       6.2.4.  Offer/Answer Considerations . . . . . . . . . . . . .  18
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
   9.  RFC Editor Considerations . . . . . . . . . . . . . . . . . .  20
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  20
     10.2.  Informative References . . . . . . . . . . . . . . . . .  22
     10.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   This document specifies a payload format for packetization of JPEG XS
   encoded video signals into the Real-time Transport Protocol (RTP)
   [RFC3550].

   The JPEG XS coding system offers compression and recompression of
   image sequences with very moderate computational resources while
   remaining robust under multiple compression and decompression cycles



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   and mixing of content sources, e.g. embedding of subtitles, overlays
   or logos.  Typical target compression ratios ensuring visually
   lossless quality are in the range of 2:1 to 10:1, depending on the
   nature of the source material.  The end-to-end latency can be
   confined to a fraction of a frame, typically between a small number
   of lines down to below a single line.

2.  Conventions, Definitions, and Abbreviations

   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 RFC 2119 [RFC2119].

   Application Data Unit (ADU)
      The unit of source data provided as payload to the transport
      layer, and corresponding, in this RTP payload definition, to a
      single JPEG XS frame.

   Colour specification box (CS box)
      A ISO colour specification box defined in ISO/IEC 21122-3
      [ISO21122-3] that includes colour-related metadata required to
      correctly display JPEG XS frames, such as colour primaries,
      transfer characteristics and matrix coefficients.

   EOC marker
      A marker that consists of the two bytes 0xff11 indicating the end
      of a JPEG XS codestream.

   JPEG XS codestream
      A sequence of bytes representing a compressed image formatted
      according to JPEG XS Part-1 [ISO21122-1].

   JPEG XS codestream header
      A sequence of bytes, starting with a SOC marker, at the beginning
      of each JPEG XS codestream encoded in multiple markers and marker
      segments that does not carry entropy coded data, but metadata such
      as the frame dimension and component precision.

   JPEG XS frame
      The concatenation of a video support box, as defined in ISO/IEC
      21122-3 [ISO21122-3], a colour specification box, as defined in
      ISO/IEC 21122-3 [ISO21122-3] as well, and either one JPEG XS
      codestream in the case of a progressive frame or two JPEG XS
      codestreams in the case of an interlaced frame.

   JPEG XS header segment
      The concatenation of a video support box, as defined in ISO/IEC
      21122-3 [ISO21122-3], a colour specification box, as defined in



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      ISO/IEC 21122-3 as well [ISO21122-3] and a JPEG XS codestream
      header.

   JPEG XS stream
      A sequence of JPEG XS frames.

   Marker
      A two-byte functional sequence that is part of a JPEG XS
      codestream starting with a 0xff byte and a subsequent byte
      defining its function.

   Marker segment
      A marker along with a 16-bit marker size and payload data
      following the size.

   Packetization unit
      A portion of a Application Data Unit whose boundaries shall
      coincide with boundaries of RTP packet payloads, i.e. the first
      (resp. last) byte of a packetization unit shall be the first
      (resp. last) byte of a RTP packet payload.

   Slice
      The smallest independently decodable unit of a JPEG XS codestream,
      bearing in mind that it decodes to wavelet coefficients which
      still require inverse wavelet filtering to give an image.

   SOC marker
      A marker that consists of the two bytes 0xff10 indicating the
      start of a JPEG XS codestream.

   Video support box (VS box)
      A ISO video support box defined in ISO/IEC 21122-3 [ISO21122-3]
      that includes metadata required to play back a JPEG XS stream,
      such as its maximum bitrate, its subsampling structure, its buffer
      model and its frame rate.

3.  Media Format Description

3.1.  Image Data Structures

   JPEG XS is a low-latency lightweight image coding system for coding
   continuous-tone grayscale or continuous-tone colour digital images.

   This coding system provides an efficient representation of image
   signals through the mathematical tool of wavelet analysis.  The
   wavelet filter process separates each component into multiple bands,
   where each band consists of multiple coefficients describing the
   image signal of a given component within a frequency domain specific



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   to the wavelet filter type, i.e. the particular filter corresponding
   to the band.

   Wavelet coefficients are grouped into precincts, where each precinct
   includes all coefficients over all bands that contribute to a spatial
   region of the image.

   One or multiple precincts are furthermore combined into slices
   consisting of an integer number of precincts.  Precincts do not cross
   slice boundaries, and wavelet coefficients in precincts that are part
   of different slices can be decoded independently from each other.
   Note, however, that the wavelet transformation runs across slice
   boundaries.  A slice always extends over the full width of the image,
   but may only cover parts of its height.

3.2.  Codestream

   A JPEG XS codestream header, followed by several slices, and
   terminated by an EOC marker form a JPEG XS codestream.

   The overall codestream format, including the definition of all
   markers, is further defined in ISO/IEC 21122-1 [ISO21122-1].  It
   represents sample values of a single image, bare any interpretation
   relative to a colour space.

3.3.  Video support box and colour specification box

   While the information defined in the codestream is sufficient to
   reconstruct the sample values of one image, the interpretation of the
   samples remains undefined by the codestream itself.  This
   interpretation is given by the video support box and the colour
   specification box which contain significant information to correctly
   play the JPEG XS stream.  The layout and syntax of these boxes,
   together with their content, are defined in ISO/IEC 21122-3
   [ISO21122-3].  The video support box provides information on the
   maximum bitrate, the frame rate, the subsampling image format, the
   timecode of the current JPEG XS frame, the profile, level and
   sublevel used (as defined in ISO/IEC 21122-2 [ISO21122-2]), and
   optionally on the buffer model and the mastering display metadata.
   The colour specification box indicates the colour primaries, transfer
   characteristics, matrix coefficients and video full range flag needed
   to specify the colour space of the video stream.

3.4.  JPEG XS Frame

   The concatenation of a video support box, a colour specification box
   and one or two JPEG XS codestreams forms a JPEG XS frame.  In the
   case of a video stream made of progressive frames, only one



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   codestream follows the boxes.  In the case of a video stream made of
   interlaced frames, two codestreams follow the boxes, each
   corresponding to a field of the interlaced frame.  The video
   information box included in the video support box contains a frat
   field indicating if the frame is progressive or interlaced (see ISO/
   IEC 21122-3 [ISO21122-3]).  This information can also be found in
   each RTP packet header (see Section 4.2).

4.  Payload Format

   This section specifies the payload format for JPEG XS streams over
   the Real-time Transport Protocol (RTP) [RFC3550].

   In order to be transported over RTP, each JPEG XS stream is
   transported in a distinct RTP stream, identified by a distinct SSRC.

   A JPEG XS stream is divided into Application Data Units (ADUs), each
   ADU corresponding to a single JPEG XS frame.

4.1.  RTP packetization

   An ADU is made of several packetization units.  If a packetization
   unit is bigger than the maximum size of a RTP packet payload, the
   unit is split into multiple RTP packet payloads, as illustrated in
   Figure 1.  As seen there, each packet shall contain (part of) one and
   only one packetization unit.  A packetization unit may extend over
   multiple packets.  The payload of every packet shall have the same
   size (based e.g. on the Maximum Transfer Unit of the network), except
   (possibly) the last packet of a packetization unit.  The boundaries
   of a packetization unit shall coincide with the boundaries of the
   payload of a packet, i.e. the first (resp. last) byte of the
   packetization unit shall be the first (resp. last) byte of the
   payload.


















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   RTP        +-----+------------------------+
   Packet #1  | Hdr | Packetization unit #1  |
              +-----+------------------------+
   RTP        +-----+--------------------------------------+
   Packet #2  | Hdr | Packetization unit #2                |
              +-----+--------------------------------------+
   RTP        +-----+--------------------------------------------------+
   Packet #3  | Hdr | Packetization unit #3  (part 1/3)                |
              +-----+--------------------------------------------------+
   RTP        +-----+--------------------------------------------------+
   Packet #4  | Hdr | Packetization unit #3  (part 2/3)                |
              +-----+--------------------------------------------------+
   RTP        +-----+----------------------------------------------+
   Packet #5  | Hdr | Packetization unit #3  (part 3/3)            |
              +-----+----------------------------------------------+
                ...
   RTP        +-----+-----------------------------------------+
   Packet #P  | Hdr | Packetization unit #N  (part q/q)       |
              +-----+-----------------------------------------+

                  Figure 1: Example of ADU packetization

   There are two different packetization modes defined for this RTP
   payload format.

   1.  Codestream packetization mode: in this mode, the packetization
       unit shall be the entire codestream, preceeded by boxes, if any.
       This means that a progressive frame will have a single
       packetization unit, while an interlaced frame will have two.  The
       progressive case is illustrated in Figure 2.

   2.  Slice packetization mode: in this mode, the packetization unit
       shall be the slice, i.e. there shall be data from no more than
       one slice per RTP packet.  The first packetization unit shall be
       made of the JPEG XS header segment (i.e. the concatenation of the
       VS box, the CS box and the JPEG XS codestream header).  This
       first unit is then followed by successive units, each containing
       one and only one slice.  The packetization unit containing the
       last slice of a JPEG XS codestream shall also contain the EOC
       marker immediately following this last slice.  This is
       illustrated in Figure 3.  In the case of interlaced frame, the
       JPEG XS codestream header of the second field shall be in its own
       packetization unit.








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   RTP        +-----+--------------------------------------------------+
   Packet #1  | Hdr | VS box + CS box + JPEG XS codestream (part 1/q)  |
              +-----+--------------------------------------------------+
   RTP        +-----+--------------------------------------------------+
   Packet #2  | Hdr | JPEG XS codestream (part 2/q)                    |
              +-----+--------------------------------------------------+
                ...
   RTP        +-----+--------------------------------------+
   Packet #P  | Hdr | JPEG XS codestream (part q/q)        |
              +-----+--------------------------------------+

            Figure 2: Example of codestream packetization mode

   RTP        +-----+----------------------------+
   Packet #1  | Hdr | JPEG XS header segment     |
              +-----+----------------------------+
   RTP        +-----+--------------------------------------------------+
   Packet #2  | Hdr | Slice #1  (part 1/2)                             |
              +-----+--------------------------------------------------+
   RTP        +-----+-------------------------------------------+
   Packet #3  | Hdr | Slice #1  (part 2/2)                      |
              +-----+-------------------------------------------+
   RTP        +-----+--------------------------------------------------+
   Packet #4  | Hdr | Slice #2  (part 1/3)                             |
              +-----+--------------------------------------------------+
                ...
   RTP        +-----+---------------------------------------+
   Packet #P  | Hdr | Slice #N  (part q/q) + EOC marker     |
              +-----+---------------------------------------+

               Figure 3: Example of slice packetization mode

   Thanks to the constant bit-rate of JPEG XS, the codestream
   packetization mode guarantees that a JPEG XS RTP stream will produce
   a constant number of bytes per frame, and a constant number of RTP
   packets per frame.  To reach the same guarantee with the slice
   packetization mode, an additional constraint needs to be set at the
   rate allocation stage in the JPEG XS encoder.  For instance, one
   option would be to impose a constant bit-rate at the slice level.

4.2.  Payload Header

   Figure 4 illustrates the RTP payload header used in order to
   transport a JPEG XS stream.







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       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 |P|X|  CC   |M|     PT      |       sequence number         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           timestamp                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           synchronization source (SSRC) identifier            |
      +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
      |            contributing source (CSRC) identifiers             |
      |                             ....                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |T|K|L| I |F counter|     SEP counter     |     P counter       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 4: RTP and payload headers

   The version (V), padding (P), extension (X), CSRC count (CC),
   sequence number, synchronization source (SSRC) and contributing
   source (CSRC) fields follow their respective definitions in RFC 3550
   [RFC3550].

   The timestamp SHOULD be based on a 90 kHz clock reference.

   As per specified in RFC 3550 [RFC3550] and RFC 4175 [RFC4175], the
   RTP timestamp designates the sampling instant of the first octet of
   the frame to which the RTP packet belongs.  Packets shall not include
   data from multiple frames, and all packets belonging to the same
   frame shall have the same timestamp.  Several successive RTP packets
   will consequently have equal timestamps if they belong to the same
   frame (that is until the marker bit is set to 1, marking the last
   packet of the frame), and the timestamp is only increased when a new
   frame begins.

   If the sampling instant does not correspond to an integer value of
   the clock, the value shall be truncated to the next lowest integer,
   with no ambiguity.

   The remaining fields are defined as follows:

   Marker (M) [1 bit]:
      The M bit is used to indicate the last packet of a frame.  This
      enables a decoder to finish decoding the frame.

   Payload Type (PT) [7 bits]:
      A dynamically allocated payload type field that designates the
      payload as JPEG XS video.




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   Transmission mode (T) [1 bit]:
      The T bit is set to indicate that packets are sent sequentially by
      the transmitter.  A receiver could use this information to
      dimension its input buffer(s) accordingly.  If T=0, nothing can be
      assumed about the transmission order and packets may be sent out-
      of-order by the transmitter.  If T=1, packets must be sent
      sequentially by the transmitter.

   pacKetization mode (K) [1 bit]:
      The K bit is set to indicate which packetization mode is used.
      K=0 indicates codestream packetization mode, while K=1 indicates
      slice packetization mode.  If Transmission mode (T) is set to 0,
      slice packetization mode must be used and K must be set to 1.

   Last (L) [1 bit]:
      The L bit is set to indicate the last packet of a packetization
      unit.  As the end of the frame also ends the packet containing the
      last unit of the frame, the L bit is set whenever the M bit is
      set.  In the case of a progressive frame using the codestream
      packetization mode, the L bit and M bit are equivalent.

   Interlaced mode (I) [2 bit]:
      These 2 bits are used to indicate how the JPEG XS frame is scanned
      (progressive or interlaced).

       00: The payload is progressively scanned.

       01: Reserved for future use.

       10: The payload is part of the first field of an interlaced video
       frame.  The height specified in the JPEG XS picture header is
       half of the height of the entire displayed image.

       11: The payload is part of the second field of an interlaced
       video frame.  The height specified in the JPEG XS picture header
       is half of the height of the entire displayed image.

   F counter [5 bits]:
      The frame (F) counter identifies the frame number modulo 32 to
      which a packet belongs.  Frame numbers are incremented by 1 for
      each frame transmitted.  The frame number, in addition to the time
      stamp, may help the decoder manage its input buffer and bring
      packets back into their natural order.

   SEP counter [11 bits]:
      The Slice and Extended Packet (SEP) counter is used differently
      depending on the packetization mode.




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      *  In the case of codestream packetization mode (K=0), this
         counter resets whenever the Packet counter resets (see
         hereunder), and increments by 1 whenever the Packet counter
         overruns.

      *  In the case of slice packetization mode (K=1), this counter
         identifies the slice modulo 2047 to which the packet
         contributes.  If the data belongs to the JPEG XS header
         segment, this field shall have its maximal value, namely 2047 =
         0x07ff.  Otherwise, it is the slice index modulo 2047.  Slice
         indices are counted from 0 (corresponding to the top of the
         frame).

   P counter [11 bits]:
      The packet (P) counter identifies the packet number modulo 2048
      within the current packetization unit.  It is set to 0 at the
      start of the packetization unit and incremented by 1 for every
      subsequent packet (if any) belonging to the same unit.
      Practically, if codestream packetization mode is enabled, this
      field counts the packets within a codestream and is extended by
      the SEP counter when it overruns.  If slice packetization mode is
      enabled, this field counts the packets within a slice or within
      the JPEG XS header segment.

4.3.  Payload Data

   The payload data of a JPEG XS RTP stream consists of a concatenation
   of multiple JPEG XS frames.

   Each JPEG XS frame is the concatenation of one or more packetization
   unit(s), as explained in Section 4.1.  Figure 5 depicts this layout
   for an interlaced frame in the codestream packetization mode and
   Figure 6 depicts this layout for a progressive frame in the slice
   packetization mode.  The Frame counter value is not indicated because
   the value is constant for all packetization units of a given frame.

 +=====[ Packetization unit (PU) #1 ]====+
 |           Video support box           |  SEP counter = 0
 |  +---------------------------------+  |  P counter = 0
 |  :      Sub boxes of the VS box    :  |
 |  +---------------------------------+  |
 +- - - - - - - - - - - - - - - - - - - -+
 |       Colour specification box        |
 |  +---------------------------------+  |
 |  :     Fields of the CS box        :  |
 |  +---------------------------------+  |
 +- - - - - - - - - - - - - - - - - - - -+
 |      JPEG XS codestream (field 0)     |



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 :             (part 1/q)                :  M=0, K=0, L=0, I=10
 +---------------------------------------+
 |      JPEG XS codestream (field 0)     |  SEP counter = 0
 |             (part 2/q)                |  P counter = 1
 :                                       :  M=0, K=0, L=0, I=10
 +---------------------------------------+
 |      JPEG XS codestream (field 0)     |  SEP counter = 0
 |             (part 3/q)                |  P counter = 2
 :                                       :  M=0, K=0, L=0, I=10
 +---------------------------------------+
 :                                       :
 +---------------------------------------+
 |      JPEG XS codestream (field 0)     |  SEP counter = 1
 |            (part 2049/q)              |  P counter = 0
 :                                       :  M=0, K=0, L=0, I=10
 +---------------------------------------+
 :                                       :
 +---------------------------------------+
 |      JPEG XS codestream (field 0)     |  SEP counter = (q-1) div 2048
 |             (part q/q)                |  P counter = (q-1) mod 2048
 :                                       :  M=0, K=0, L=1, I=10
 +===============[ PU #2 ]===============+
 |      JPEG XS codestream (field 1)     |  SEP counter = 0
 |             (part 1/q)                |  P counter = 0
 :                                       :  M=0, K=0, L=0, I=11
 +---------------------------------------+
 |      JPEG XS codestream (field 1)     |  SEP counter = 0
 |             (part 2/q)                |  P counter = 1
 :                                       :  M=0, K=0, L=0, I=11
 +---------------------------------------+
 :                                       :
 +---------------------------------------+
 |      JPEG XS codestream (field 1)     |  SEP counter = (q-1) div 2048
 |             (part q/q)                |  P counter = (q-1) mod 2048
 :                                       :  M=1, K=0, L=1, I=11
 +=======================================+


    Figure 5: Example of JPEG XS Payload Data (codestream packetization
                          mode, interlaced frame)

   +====[ PU#1: JPEG XS Header segment ]===+
   |           Video support box           |  SEP counter = 0x07FF
   |  +---------------------------------+  |  P counter = 0
   |  :      Sub boxes of the VS box    :  |
   |  +---------------------------------+  |
   +- - - - - - - - - - - - - - - - - - - -+
   |       Colour specification box        |



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   |  +---------------------------------+  |
   |  :     Fields of the CS box        :  |
   |  +---------------------------------+  |
   +- - - - - - - - - - - - - - - - - - - -+
   |      JPEG XS codestream header        |
   |  +---------------------------------+  |
   |  :  Markers and marker segments    :  |
   |  +---------------------------------+  |  M=0, T=0, K=1, L=1, I=00
   +==========[ PU#2: Slice #1 ]===========+
   |  +---------------------------------+  |  SEP counter = 0
   |  |           SLH Marker            |  |  P counter = 0
   |  +---------------------------------+  |
   |  :       Entropy Coded Data        :  |
   |  +---------------------------------+  |  M=0, T=0, K=1, L=1, I=00
   +==========[ PU#3: Slice #2 ]===========+
   |               Slice #2                |  SEP counter = 1
   |              (part 1/q)               |  P counter = 0
   :                                       :  M=0, T=0, K=1, L=0, I=00
   +---------------------------------------+
   |               Slice #2                |  SEP counter = 1
   |              (part 2/q)               |  P counter = 1
   :                                       :  M=0, T=0, K=1, L=0, I=00
   +---------------------------------------+
   :                                       :
   +---------------------------------------+
   |               Slice #2                |  SEP counter = 1
   |              (part q/q)               |  P counter = q-1
   :                                       :  M=0, T=0, K=1, L=1, I=00
   +=======================================+
   :                                       :
   +========[ PU#N: Slice #(N-1) ]=========+
   |             Slice #(N-1)              |  SEP counter = N-2
   |              (part 1/r)               |  P counter = 0
   :                                       :  M=0, T=0, K=1, L=0, I=00
   +---------------------------------------+
   :                                       :
   +---------------------------------------+
   |             Slice #(N-1)              |  SEP counter = N-2
   |              (part r/r)               |  P counter = r-1
   :             + EOC marker              :  M=1, T=0, K=1, L=1, I=00
   +=======================================+


   Figure 6: Example of JPEG XS Payload Data (slice packetization mode,
                            progressive frame)






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4.4.  Traffic Shaping and Delivery Timing

   The traffic shaping and delivery timing shall be in accordance with
   the Network Compatibility Model compliance definitions specified in
   SMPTE ST 2110-21 [SMPTE-ST2110-21] for either Narrow Linear Senders
   (Type NL) or Wide Senders (Type W).  The session description shall
   include a format-specific parameter of either TP=2110TPNL or
   TP=2110TPW to indicate compliance with Type NL or Type W
   respectively.

   NOTE: The Virtual Receiver Buffer Model compliance definitions of ST
   2110-21 do not apply.

5.  Congestion Control Considerations

   Congestion control for RTP SHALL be used in accordance with RFC 3550
   [RFC3550], and with any applicable RTP profile: e.g., RFC 3551
   [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
   and applications implementing this standard MUST comply with it.  RFC
   8085 [RFC8085] provides additional information on the best practices
   for applying congestion control to UDP streams.

6.  Payload Format Parameters

6.1.  Media Type Definition

   Type name:  video

   Subtype name:  jxsv

   Required parameters:

     rate: The RTP timestamp clock rate.  Applications using this
     payload format SHOULD use a value of 90000.

     transmission mode: Indicates if packets are sent sequentially by
     the transmitter.  A receiver could use this information to
     dimension its input buffer(s) accordingly.  If set to 0, nothing
     can be assumed about the transmission order and packets may be sent
     out-of-order.  If value is 1, packets must be sent sequentially by
     the transmitter.

   Optional parameters:




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     profile: The JPEG XS profile in use, as defined in ISO/IEC 21122-2
     (JPEG XS Part 2) [ISO21122-2].

     level: The JPEG XS level in use, as defined in ISO/IEC 21122-2
     (JPEG XS Part 2) [ISO21122-2].

     sublevel: The JPEG XS sublevel in use, as defined in ISO/IEC
     21122-2 (JPEG XS Part 2) [ISO21122-2].

     sampling: Signals the colour difference signal sub-sampling
     structure.

     Signals utilizing the non-constant luminance Y'C'B C'R signal
     format of Recommendation ITU-R BT.601-7, Recommendation ITU-R
     BT.709-6, Recommendation ITU-R BT.2020-2, or Recommendation ITU-R
     BT.2100 shall use the appropriate one of the following values for
     the Media Type Parameter "sampling":

          YCbCr-4:4:4 (4:4:4 sampling)
          YCbCr-4:2:2 (4:2:2 sampling)
          YCbCr-4:2:0 (4:2:0 sampling)

     Signals utilizing the Constant Luminance Y'C C'BC C'RC signal
     format of Recommendation ITU-R BT.2020-2 shall use the appropriate
     one of the following values for the Media Type Parameter
     "sampling":

          CLYCbCr-4:4:4 (4:4:4 sampling)
          CLYCbCr-4:2:2 (4:2:2 sampling)
          CLYCbCr-4:2:0 (4:2:0 sampling)

     Signals utilizing the constant intensity I CT CP signal format of
     Recommendation ITU-R BT.2100 shall use the appropriate one of the
     following values for the Media Type Parameter "sampling":

          ICtCp-4:4:4 (4:4:4 sampling)
          ICtCp-4:2:2 (4:2:2 sampling)
          ICtCp-4:2:0 (4:2:0 sampling)

     Signals utilizing the 4:4:4 R' G' B' or RGB signal format (such as
     that of Recommendation ITU-R BT.601, Recommendation ITU-R BT.709,
     Recommendation ITU-R BT.2020, Recommendation ITU-R BT.2100, SMPTE
     ST 2065-1 or ST 2065-3) shall use the following value for the Media
     Type Parameter sampling.

          RGB    RGB or R' G' B' samples





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     Signals utilizing the 4:4:4 X' Y' Z' signal format (such as defined
     in SMPTE ST 428-1) shall use the following value for the Media Type
     Parameter sampling.

          XYZ    X' Y' Z' samples

     Key signals as defined in SMPTE RP 157 shall use the value key for
     the Media Type Parameter sampling.  The Key signal is represented
     as a single component.

          KEY    samples of the key signal

     depth: Determines the number of bits per sample.  This is an
     integer with typical values including 8, 10, 12, and 16.

     width: Determines the number of pixels per line.  This is an
     integer between 1 and 32767.

     height: Determines the number of lines per frame.  This is an
     integer between 1 and 32767.

     exactframerate: Signals the frame rate in frames per second.
     Integer frame rates shall be signaled as a single decimal number
     (e.g. "25") whilst non-integer frame rates shall be signaled as a
     ratio of two integer decimal numbers separated by a "forward-slash"
     character (e.g. "30000/1001"), utilizing the numerically smallest
     numerator value possible.

     colorimetry: Specifies the system colorimetry used by the image
     samples.  Valid values and their specification are:

          BT601-5      ITU Recommendation BT.601-5
          BT709-2      ITU Recommendation BT.709-2
          SMPTE240M    SMPTE standard 240M
          BT601        as specified in Recommendation ITU-R BT.601-7
          BT709        as specified in Recommendation ITU-R BT.709-6
          BT2020       as specified in Recommendation ITU-R BT.2020-2
          BT2100       as specified in Recommendation ITU-R BT.2100
                       Table 2 titled "System colorimetry"
          ST2065-1     as specified in SMPTE ST 2065-1 Academy Color
                       Encoding Specification (ACES)
          ST2065-3     as specified for Academy Density Exchange
                       Encoding (ADX) in SMPTE ST 2065-3
          XYZ          as specified in ISO 11664-1 section titled
                       "1931 Observer"






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     Signals utilizing the Recommendation ITU-R BT.2100 colorimetry
     should also signal the representational range using the optional
     parameter RANGE defined below.

     interlace: If this OPTIONAL parameter name is present, it indicates
     that the video is interlaced.  If this parameter name is not
     present, the progressive video format shall be assumed.

     TCS: Transfer Characteristic System.  This parameter specifies the
     transfer characteristic system of the image samples.  Valid values
     and their specification are:

          SDR    (Standard Dynamic Range) Video streams of standard
                 dynamic range, that utilize the OETF of Recommendation
                 ITU-R BT.709 or Recommendation ITU-R BT.2020. Such
                 streams shall be assumed to target the EOTF specified
                 in ITU-R BT.1886.
          PQ     Video streams of high dynamic range video that utilize
                 the Perceptual Quantization system of Recommendation
                 ITU-R BT.2100
          HLG    Video streams of high dynamic range video that utilize
                 the Hybrid Log-Gamma system of Recommendation ITU-R
                 BT.2100

     RANGE: This parameter should be used to signal the encoding range
     of the sample values within the stream.  When paired with ITU Rec
     BT.2100 colorimetry, this parameter has two allowed values NARROW
     and FULL, corresponding to the ranges specified in table 9 of ITU
     Rec BT.2100.  In any other context, this parameter has three
     allowed values: NARROW, FULLPROTECT, and FULL, which correspond to
     the ranges specified in SMPTE RP 2077.  In the absence of this
     parameter, NARROW shall be the assumed value in either case.

   Encoding considerations:
    This media type is framed and binary; see Section 4.8 in RFC 6838
    [RFC6838].

   Security considerations:
    Please see the Security Considerations section in RFC XXXX

6.2.  Mapping to SDP

6.2.1.  General

   A Session Description Protocol (SDP) object shall be created for each
   RTP stream and it shall be in accordance with the provisions of SMPTE
   ST 2110-10 [SMPTE-ST2110-10].




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   The information carried in the media type specification has a
   specific mapping to fields in the Session Description Protocol (SDP),
   which is commonly used to describe RTP sessions.

6.2.2.  Media type and subtype

   The media type ("video") goes in SDP "m=" as the media name.

   The media subtype ("jxsv") goes in SDP "a=rtpmap" as the encoding
   name, followed by a slash ("/") and the required parameter "rate"
   corresponding to the RTP timestamp clock rate (which for the payload
   format defined in this document SHOULD be 90000), followed by a slash
   ("/") and the required parameter "transmission mode" set to 1 if
   packets are sent sequentially by the transmitter, or 0 if
   transmission order is not constrained.  The optional parameters go in
   the SDP "a=fmtp" attribute by copying them directly from the MIME
   media type string as a semicolon-separated list of parameter=value
   pairs.

   A sample SDP mapping for JPEG XS video is as follows:

        m=video 30000 RTP/AVP 112
        a=rtpmap:112 jxsv/90000/1
        a=fmtp:112 sampling=YCbCr-4:2:2; width=1920; height=1080;
                   depth=10; colorimetry=BT709; TCS=SDR;
                   RANGE=FULL; TP=2110TPNL

   In this example, a JPEG XS RTP stream is being sent to UDP
   destination port 30000, with an RTP dynamic payload type of 112 and a
   media clock rate of 90000 Hz.  Note that the "a=fmtp:" line has been
   wrapped to fit this page, and will be a single long line in the SDP
   file.

6.2.3.  Traffic shaping

   The SDP object shall include the TP parameter (either 2110TPNL or
   2110TPW as specified in Section 4.4) and may include the CMAX
   parameter as specified in SMPTE ST 2110-21 [SMPTE-ST2110-21].

6.2.4.  Offer/Answer Considerations

   The following considerations apply when using SDP offer/answer
   procedures [RFC3264] to negotiate the use of the JPEG XS payload in
   RTP:

   o  The "encode" parameter can be used for sendrecv, sendonly, and
      recvonly streams.  Each encode type MUST use a separate payload
      type number.



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   o  Any unknown parameter in an offer MUST be ignored by the receiver
      and MUST NOT be included in the answer.

7.  IANA Considerations

   This memo requests that IANA registers video/jxsv as specified in
   Section 6.1.  The media type is also requested to be added to the
   IANA registry for "RTP Payload Format MIME types" [1].

8.  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].  This implies that confidentiality of the media
   streams is achieved by encryption.

   However, as "Securing the RTP Framework: Why RTP Does Not Mandate a
   Single Media Security Solution" [RFC7202] discusses, it is not an RTP
   payload format's responsibility to discuss or mandate what solutions
   are used to meet the basic security goals like confidentiality,
   integrity, and source authenticity for RTP in general.  This
   responsibility lies 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.

   This payload format and the JPEG XS encoding do not exhibit any
   substantial non-uniformity, either in output or in complexity to
   perform the decoding operation and thus are unlikely to pose a
   denial-of-service threat due to the receipt of pathological
   datagrams.

   It is important to note that HD or UHDTV JPEG XS-encoded video can
   have significant bandwidth requirements (typically more than 1 Gbps
   for ultra high-definition video, especially if using high framerate).
   This is sufficient to cause potential for denial-of-service if
   transmitted onto most currently available Internet paths.

   Accordingly, if best-effort service is being used, users of this
   payload format MUST monitor packet loss to ensure that the packet
   loss rate is within acceptable parameters.  Packet loss is considered
   acceptable if a TCP flow across the same network path, and
   experiencing the same network conditions, would achieve an average
   throughput, measured on a reasonable timescale, that is not less than
   the RTP flow is achieving.  This condition can be satisfied by



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   implementing congestion control mechanisms to adapt the transmission
   rate (or the number of layers subscribed for a layered multicast
   session), or by arranging for a receiver to leave the session if the
   loss rate is unacceptably high.

   This payload format may also be used in networks that provide
   quality-of-service guarantees.  If enhanced service is being used,
   receivers SHOULD monitor packet loss to ensure that the service that
   was requested is actually being delivered.  If it is not, then they
   SHOULD assume that they are receiving best-effort service and behave
   accordingly.

9.  RFC Editor Considerations

   Note to RFC Editor: This section may be removed after carrying out
   all the instructions of this section.

   RFC XXXX is to be replaced by the RFC number this specification
   receives when published.

10.  References

10.1.  Normative References

   [ISO21122-1]
              International Organization for Standardization (ISO) -
              International Electrotechnical Commission (IEC),
              "Information technology - JPEG XS low-latency lightweight
              image coding system - Part 1: Core coding system", ISO/
              IEC PRF 21122-1, under development,
              <https://www.iso.org/standard/74535.html>.

   [ISO21122-2]
              International Organization for Standardization (ISO) -
              International Electrotechnical Commission (IEC),
              "Information technology - JPEG XS low-latency lightweight
              image coding system - Part 2: Profiles and buffer models",
              ISO/IEC PRF 21122-2, under development,
              <https://www.iso.org/standard/74536.html>.

   [ISO21122-3]
              International Organization for Standardization (ISO) -
              International Electrotechnical Commission (IEC),
              "Information technology - JPEG XS low-latency lightweight
              image coding system - Part 3: Transport and container
              formats", ISO/IEC FDIS 21122-3, under development,
              <https://www.iso.org/standard/74537.html>.




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   [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>.

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              DOI 10.17487/RFC3264, June 2002,
              <https://www.rfc-editor.org/info/rfc3264>.

   [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>.

   [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>.

   [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>.

   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <https://www.rfc-editor.org/info/rfc8085>.

   [SMPTE-ST2110-10]
              Society of Motion Picture and Television Engineers, "SMPTE
              Standard - Professional Media Over Managed IP Networks:
              System Timing and Definitions", SMPTE ST 2110-10:2017,
              2017, <https://doi.org/10.5594/SMPTE.ST2110-10.2017>.







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   [SMPTE-ST2110-21]
              Society of Motion Picture and Television Engineers, "SMPTE
              Standard - Professional Media Over Managed IP Networks:
              Traffic Shaping and Delivery Timing for Video", SMPTE ST
              2110-21:2017, 2017,
              <https://doi.org/10.5594/SMPTE.ST2110-21.2017>.

10.2.  Informative References

   [RFC4175]  Gharai, L. and C. Perkins, "RTP Payload Format for
              Uncompressed Video", RFC 4175, DOI 10.17487/RFC4175,
              September 2005, <https://www.rfc-editor.org/info/rfc4175>.

   [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>.

   [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>.

   [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>.

10.3.  URIs

   [1] http://www.iana.org/assignments/rtp-parameters

Authors' Addresses

   Sebastien Lugan
   intoPIX S.A.
   Rue Emile Francqui, 9
   1435 Mont-Saint-Guibert
   Belgium

   Phone: +32 10 23 84 70
   Email: rtp@intopix.com
   URI:   http://www.intopix.com



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   Antonin Descampe
   intoPIX S.A.
   Rue Emile Francqui, 9
   1435 Mont-Saint-Guibert
   Belgium

   Phone: +32 10 23 84 70
   Email: a.descampe@intopix.com
   URI:   http://www.intopix.com


   Corentin Damman
   intoPIX S.A.
   Rue Emile Francqui, 9
   1435 Mont-Saint-Guibert
   Belgium

   Phone: +32 10 23 84 70
   Email: c.damman@intopix.com
   URI:   http://www.intopix.com


   Thomas Richter
   Fraunhofer IIS
   Am Wolfsmantel 33
   91048 Erlangen
   Germany

   Phone: +49 9131 776 5126
   Email: thomas.richter@iis.fraunhofer.de
   URI:   https://www.iis.fraunhofer.de/


   Alexandre Willeme
   Universite catholique de Louvain
   Place du Levant, 2 - bte L5.04.04
   1348 Louvain-la-Neuve
   Belgium

   Phone: +32 10 47 80 82
   Email: alexandre.willeme@uclouvain.be
   URI:   https://uclouvain.be/en/icteam









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