



Media Over QUIC                                                   W. Law
Internet-Draft                                                    Akamai
Intended status: Informational                           1 December 2025
Expires: 4 June 2026


     CMSF- a CMAF compliant implementation of MOQT Streaming Format
                         draft-ietf-moq-cmsf-00

Abstract

   This document updates [MSF] by defining a new optional feature for
   the streaming format.  It specifies the syntax and semantics for
   adding CMAF-packaged media [CMAF] to MSF.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://moq-
   wg.github.io/cmsf/draft-wilaw-moq-cmsf.html.  Status information for
   this document may be found at https://datatracker.ietf.org/doc/draft-
   ietf-moq-cmsf/.

   Discussion of this document takes place on the Media Over QUIC
   Working Group mailing list (mailto:moq@ietf.org), which is archived
   at https://mailarchive.ietf.org/arch/browse/moq/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/moq/.

   Source for this draft and an issue tracker can be found at
   https://github.com/moq-wg/cmsf.

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 4 June 2026.



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Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  MSF Extension . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  CMAF Packaging  . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Initialization headers  . . . . . . . . . . . . . . . . .   3
     3.2.  Switching sets and tracks . . . . . . . . . . . . . . . .   3
     3.3.  Object Packaging  . . . . . . . . . . . . . . . . . . . .   3
     3.4.  Group Packaging . . . . . . . . . . . . . . . . . . . . .   4
     3.5.  Catalog description . . . . . . . . . . . . . . . . . . .   4
       3.5.1.  CMAF packaging type . . . . . . . . . . . . . . . . .   4
       3.5.2.  Max SAP starting types  . . . . . . . . . . . . . . .   4
     3.6.  Event Timelines . . . . . . . . . . . . . . . . . . . . .   5
       3.6.1.  SAP Type timeline . . . . . . . . . . . . . . . . . .   5
       3.6.2.  SAP-type timeline track example . . . . . . . . . . .   6
   4.  Catalog Examples  . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Simulcast video tracks - 3 alternate video qualities along
           with audio  . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Conventions and Definitions . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   CMAF compliant MOQT Streaming Format (CMSF) is a media format
   designed to deliver CMAF [CMAF] and LOC [LOC] compliant media content
   over MOQ Transport (MOQT) [MoQTransport].  CMSF extends MSF and
   retains all the scope, capabilities and features of MSF including the
   catalog format, timeline, ABR switching and LOC support.  MSF is
   targeted at real-time and interactive levels of live latency, as well
   as VOD content.



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   This document describes version 1 of the CMSF streaming format.

2.  MSF Extension

   All of the specifications, requirements, and terminology defined in
   [MSF] apply to implementations of this extension unless explicitly
   noted otherwise in this document.

3.  CMAF Packaging

3.1.  Initialization headers

   A CMAF header is a sequence of CMAF constrained ISO BMFF boxes that
   do not reference any media samples, but are associated with a CMAF
   track and are necessary for initializing the decoding of the
   subsequent CMAF fragments.

   The header for a given MOQT Track MUST be packaged by encoding the
   header using [BASE64] and then inserting that payload as the value of
   the Initialization data "initData" field in the catalog entry for
   that Track.

3.2.  Switching sets and tracks

   This specification defines a direct mapping between CMAF Tracks (
   [CMAF] Sect 3.2.1) and MOQT tracks ([MoQTransport] Sect 2.3).

   CMAF switching sets are a set of one or more CMAF tracks (3.2.1),
   where each track is an alternative encoding of the same source
   content and are constrained to enable seamless track switching
   (3.3.9).

   Each CMAF track in a switching set MUST be transmitted as a separate
   MOQT Track.  The catalog entry for each of these tracks in the
   switching set MUST carry a Alternate group (altGroup) key with a
   common value.

   The MOQT Group numbers within these switching set tracks MUST be
   media time-aligned.  Mandating the track being media time-aligned
   requires that the presentation time of the first media sample
   contained within the first MOQT Object of each MOQT Group is
   identical.

3.3.  Object Packaging

   The payload of each Object is subject to the following requirements:





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   *  MUST contain at least one Movie Fragment Box (moof) followed by a
      Media Data Box (mdat).  This is equivalent to requiring that each
      Object hold at least one CMAF Chunk.  The Media Fragment Box
      (moof) MUST contain a Movie Fragment Header Box (mfhd) and Track
      Box (trak) with a Track ID (track_ID) matching a Track Box in the
      initialization fragment.

   *  MAY contain multiple successive CMAF Chunks.

   *  MUST contain a single [ISOBMFF] track.

   *  MUST contain media content encoded in decode order.

3.4.  Group Packaging

   Each MOQT Group

   *  MUST begin with an Object containing a stream access point (SAP
      type 1 or 2).

   *  MUST contain one or more contiguous Groups of Pictures (GOPs).

   *  The Group boundary MUST align with a CMAF Fragment boundary.  CMAF
      Fragments and CMAF Chunks MUST not span Groups.

3.5.  Catalog description

3.5.1.  CMAF packaging type

   This specification extends the allowed packaging values defined in
   [MSF] to include one new entry, as defined in Table 1 below:

                       +======+=======+===========+
                       | Name | Value | Reference |
                       +======+=======+===========+
                       | CMAF | cmaf  | This RFC  |
                       +------+-------+-----------+

                                 Table 1

   Every Track entry in a CMSF catalog carrying CMAF-packaged media data
   MUST declare a "packaging" type value of "cmaf".

3.5.2.  Max SAP starting types

   This specification adds two track-level catalog fields, as defined in
   Table 2 below:




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   +=============================+=======================+============+
   | Field                       | Name                  | Definition |
   +=============================+=======================+============+
   | Max Group SAP starting type | maxGrpSapStartingType | Section    |
   |                             |                       | 3.5.2.1    |
   +-----------------------------+-----------------------+------------+
   | Max Object SAP starting     | maxObjSapStartingType | Section    |
   | type                        |                       | 3.5.2.2    |
   +-----------------------------+-----------------------+------------+

                                 Table 2

3.5.2.1.  Max Group SAP starting type

   Location: T Required: Optional JSON Type: Number

   A number indicating the maximum SAP type the MOQT Groups in the track
   start with.

3.5.2.2.  Max Object SAP starting type

   Location: T Required: Optional JSON Type: Number

   A number indicating the maximum SAP type the MOQT Objects in the
   track start with.

3.6.  Event Timelines

3.6.1.  SAP Type timeline

   CMSF defines a special instance of an Event Timeline track, termed
   the SAP Type timeline track.  Its purpose is to convey information
   about the distribution of Stream Access Point types and their
   associated Earlist Presentation Times.

   In the catalog, the SAP-type timeline track MUST include a
   'packaging' value of 'eventtimeline" and MUST include an 'eventType'
   value of 'org.ietf.moq.cmsf.sap'.

   In the SAP Type timeline JSON payload:

   *  The index reference MUST be 'l' for Location

   *  The data field is a JSON Array containing two integers.  The first
      integer defines SAP type with an allowed value of 0,1,2 or 3.  The
      value 0 indicates that the Object does not start with an ISOBMFF
      stream access point.  The value equal to 1, 2, or 3 indicates that
      the Object begins with a stream access point of SAP type 1, 2, or



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      3, respectively.  When the Object is the first Object in the
      Group, the value MUST be equal to 1 or 2.  The second integer
      defines the earliest media presentation timestamp, rounded to the
      nearest millisecond, of all media samples in the Object defined by
      the Location of that record.

3.6.2.  SAP-type timeline track example

   This shows an example of 30-fps HEVC-encoded content, in which each
   4s Group beings with SAP-type 2 (i.e., the first picture in the Group
   is an IDR picture, while there may be one or more pictures in the
   Group following the IDR picture in decoding order but preceding it in
   output order).  After 2 seconds in each Group, there is a SAP-type 3,
   i.e., a CRA picture, which is associated with one or more Random
   Access Skipped Leading (RASL) pictures.  A small buffer of frames (10
   frames at 30 fps) is skipped/discarded (RASL pictures) when the
   streaming session starts from the SAP-type 3 location.  In this
   example, the EPT is the presentation time of the first picture after
   the RASL pictures in decoding order; all pictures after the RASL
   pictures can be fully correctly decoded and are thus presentable when
   the streaming session starts from the SAP-type 3 location.  Note that
   if the streaming session starts from the start of the Group, then
   these RASL pictures can be fully correctly decoded and are thus
   presentable.

   [
       {
           "l": [0,0],
           "data": [2,0]
       },
       {
           "l": [0,60],
           "data": [3,2100]
       },
       {
           "l": [1,0],
           "data": [2,4000]
       },
       {
           "l": [1,60],
           "data": [3,6100]
       }
   ]

4.  Catalog Examples

   The following section provides non-normative JSON examples of various
   catalogs compliant with this draft.



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4.1.  Simulcast video tracks - 3 alternate video qualities along with
      audio

   This example shows catalog for a media producer capable of sending 3
   time-aligned video tracks for high definition, low definition and
   medium definition video qualities, along with an audio track.

   {
     "version": 1,
     "generatedAt": 1746104606044,
     "tracks":[
       {
         "name": "hd",
         "renderGroup": 1,
         "packaging": "cmaf",
         "isLive": true,
         "initData": "AAAAIGZ0eXBpc281AAA...AAAAAAAAAAAAA",
         "role": "video",
         "codec":"avc1.640028",
         "width":1920,
         "height":1080,
         "bitrate":5000000,
         "framerate":30,
         "altGroup":1
       },
       {
         "name": "md",
         "renderGroup": 1,
         "packaging": "cmaf",
         "isLive": true,
         "initData": "AAAAHGZ0eXBpc281AAA...AAAAAAAAAAAAAA",
         "role": "video",
         "codec":"avc1.64001e",
         "width":720,
         "height":640,
         "bitrate":3000000,
         "framerate":30,
         "altGroup":1
       },
       {
         "name": "sd",
         "renderGroup": 1,
         "packaging": "cmaf",
         "isLive": true,
         "initData": "AAAAHGZ0eXBpc281AAA...AAAAAAAAAAAAAA",
         "role": "video",
         "codec":"avc1.64000d",
         "width":192,



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         "height":144,
         "bitrate":500000,
         "framerate":30,
         "altGroup":1
       },
       {
         "name": "audio",
         "renderGroup": 1,
         "packaging": "cmaf",
         "isLive": true,
         "initData": "AAAAHGZ0eXBpc281AAA...AAAAAAAAAAAAAA",
         "role": "audio",
         "codec":"mp4a.40.5",
         "samplerate":48000,
         "channelConfig":"2",
         "bitrate":67071
       }
      ]
   }

5.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

6.  Security Considerations

   TODO Security

7.  IANA Considerations

   This document has no IANA actions.

8.  Normative References

   [BASE64]   Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/rfc/rfc4648>.

   [CMAF]     Standardization, I. O. for., "Information technology —
              Multimedia application format (MPEG-A) — Part 19: Common
              media application format (CMAF) for segmented media",
              October 2021.





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   [MoQTransport]
              Curley, L., Pugin, K., Nandakumar, S., Vasiliev, V., and
              I. Swett, "Media over QUIC Transport", Work in Progress,
              Internet-Draft, draft-ietf-moq-transport-10, 3 March 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-moq-
              transport-10>.

   [MSF]      Law, W., Curley, L., Vasiliev, V., Nandakumar, S., and K.
              Pugin, "WARP Streaming Format", Work in Progress,
              Internet-Draft, draft-ietf-moq-warp-01, 22 July 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-moq-
              warp-01>.

   [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/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

Acknowledgments

   TODO acknowledge.

Author's Address

   Will Law
   Akamai
   Email: wilaw@akamai.com




















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