Internet DRAFT - draft-wilaw-moq-cmafpackaging
draft-wilaw-moq-cmafpackaging
Media Over QUIC W. Law
Internet-Draft Akamai
Intended status: Informational L. Curley
Expires: 4 April 2024 2 October 2023
CMAF Packaging for moq-transport
draft-wilaw-moq-cmafpackaging-00
Abstract
Packaging CMAF content for use with moq-transport.
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://wilaw.github.io/moq-cmaf-packaging/draft-wilaw-moq-
cmafpackaging.html. Status information for this document may be
found at https://datatracker.ietf.org/doc/draft-wilaw-moq-
cmafpackaging/.
Discussion of this document takes place on the Media Over QUIC
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Source for this draft and an issue tracker can be found at
https://github.com/wilaw/moq-cmaf-packaging.
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This Internet-Draft will expire on 4 April 2024.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Media Object Payload . . . . . . . . . . . . . . . . . . . . 3
4. Mapping CMAF objects to MOQT Streams . . . . . . . . . . . . 3
4.1. CMAF Fragment to MOQT Group . . . . . . . . . . . . . . . 3
4.2. CMAF Chunk to MOQT Object . . . . . . . . . . . . . . . . 3
5. Switching sets . . . . . . . . . . . . . . . . . . . . . . . 4
6. Initialization headers . . . . . . . . . . . . . . . . . . . 4
6.1. Binary objects . . . . . . . . . . . . . . . . . . . . . 4
6.2. MOQT Tracks . . . . . . . . . . . . . . . . . . . . . . . 4
7. Content protection and encryption . . . . . . . . . . . . . . 4
8. Conventions and Definitions . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
11. Normative References . . . . . . . . . . . . . . . . . . . . 5
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This specification defines an interoperable method of transmitting
CMAF [CMAF] compliant media content over Media Over QUIC Transport
(MOQT) [MoQTransport]. Multiple mappings are supported, including
mapping complete Groups of Pictures (GOPS) [ISOBMFF] or individual
frames to MoQTransport Objects. This specification is intended to be
referenced by MOQT-compliant Streaming Formats.
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2. 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 RFC
2119 [RFC2119].
3. Media Object Payload
This specification defines a direct mapping between CMAF Tracks (
[CMAF] Sect 3.2.1) and MOQT tracks ([MoQTransport] Sect 2.3). As a
consequence, the MOQT Object payload:
* MUST consist of a Segment Type Box (styp) followed by any number
of media fragments. Each media fragment consists of a Movie
Fragment Box (moof) followed by a Media Data Box (mdat). 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.
* MUST contain a single [ISOBMFF] track.
* MUST contain media content encoded in decode order. This implies
an increasing decoding time stamp (DTS).
* MAY contain any number of frames/samples.
* MAY have gaps between frames/samples.
* MAY overlap with other objects. This means timestamps may be
interleaved between objects.
4. Mapping CMAF objects to MOQT Streams
This specification defines two methods for mapping CMAF objects to
MOQT objects:
4.1. CMAF Fragment to MOQT Group
A complete CMAF Fragment (see [CMAF] sect 6.6.1) into a single object
within each group. This results in there being a single GOP (Group
of Pictures) in the media object and a single media object per group.
4.2. CMAF Chunk to MOQT Object
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* Each CMAF chunk (see [CMAF] sect 6.6.5) in a separate MOQT Object.
All MOQT Objects holding chunks from the same parent fragment MUST
belong to the same MOQT Group. A new MOQT Group MUST be generated
for each new CMAF Fragment.
5. Switching sets
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). If such switching sets are to be transported over MOQT,
irrespective of the mapping of CMAF Objects to MOQT Streams, then
MOQT Group numbers MUST be media time-aligned between the MOQT
tracks. 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.
6. Initialization headers
A CMAF header is sequence of CMAF constrained ISO BMFF boxes that do
not reference any media samples (3.3.15), but are associated with a
CMAF track (3.2.1) and necessary for the decoding of its CMAF
fragments (3.1.1). The header for a given MOQT Track may be packaged
in one of two ways:
6.1. Binary objects
As a binary blob which is communicated to the client via a mechanism
defined by the streaming format.
6.2. MOQT Tracks
As a MOQT Track. In this case the track MUST have only a single
GROUP and a single OBJECT. The payload of the object MUST be the
complete initialization header. The mapping of this initialization
MOQT TRACK to the MOQT track which it initializes is defined by the
streaming format.
7. Content protection and encryption
The media object payloads MAY be encrypted. If the content is
encryptedm then Common Encryption [CENC] MUST be used. CMAF Track
encruption MUST be applied following [CENC] Sectino 8.2. CENC with
'cbcs' mode (AES CBC with pattern encryption) is the RECOMMENDED
encryption method.
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Any license acquisition information used to acquire CMAF decryption
key(s) MUST be signalled by the Streaming Format, and not in the CMAF
header.
8. 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.
9. Security Considerations
TODO Security
10. IANA Considerations
This document has no IANA actions.
11. Normative References
[CENC] "International Organization for Standardization -
Information technology - MPEG systems technologies - Part
7: Common encryption in ISO base media file format files",
December 2020.
[CMAF] "Information technology -- Multimedia application format
(MPEG-A) -- Part 19: Common media application format
(CMAF) for segmented media", March 2020.
[ISOBMFF] "Information technology -- Coding of audio-visual objects
-- Part 12: ISO Base Media File Format", December 2015.
[MoQTransport]
Curley, L., Pugin, K., Nandakumar, S., and V. Vasiliev,
"Media over QUIC Transport", Work in Progress, Internet-
Draft, draft-lcurley-moq-transport-00, 26 May 2023,
<https://datatracker.ietf.org/doc/html/draft-lcurley-moq-
transport-00>.
[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>.
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[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.
Authors' Addresses
Will Law
Akamai
Email: wilaw@akamai.com
Luke Curley
Email: kixelated@gmail.com
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