ISO/IEC 23000-19:2018
(Main)Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media
Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media
ISO/IEC 23000-19:2018 specifies the CMAF multimedia format, which contains segmented media objects optimized for streaming delivery and decoding on end user devices in adaptive multimedia presentations. CMAF specifies a track format derived from the ISO Base Media File Format, then derives addressable media objects from CMAF tracks that can be used for storage and delivery. CMAF specifies sets of tracks that share encoding and packaging constraints that enable the selection of multiple tracks to form a multimedia presentation and allow seamless switching of alternative encodings of the same content at different bit rates, frame rates, resolution, etc. CMAF specifies a hypothetical application model that determines how tracks in a CMAF presentation are intended to be combined and synchronized to form a multimedia presentation. The model abstracts delivery to allow any delivery method. The hypothetical application model assumes a manifest and player, but CMAF does not specify a manifest, player, or delivery protocol, with the intent that any that support the hypothetical application model can be used. CMAF specifies media profiles and brands that constrain media encoding and packaging of CMAF tracks to enable seamless adaptive switching of tracks and allow devices to identify compatible content by its brand. CMAF specifies presentation profiles that conditionally require sets of CMAF tracks conforming to specified media profiles and allow content creators and devices to identify compatible multimedia presentations. CMAF enables extensibility by specifying how new media profiles and presentation profiles can be specified and identified and includes guidelines for those specifications.
Technologies de l'information — Format pour application multimédia (MPEG-A) — Partie 19: Format CMAF (Common Media Application Format) pour médias segmentés
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Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 23000-19
First edition
2018-01
Information technology — Multimedia
application format (MPEG-A) —
Part 19:
Common media application format
(CMAF) for segmented media
Technologies de l'information — Format pour application multimédia
(MPEG-A) —
Partie 19: Format CMAF (Common Media Application Format) pour
médias segmentés
Reference number
ISO/IEC 23000-19:2018(E)
©
ISO/IEC 2018
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ISO/IEC 23000-19:2018(E)
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ISO/IEC 23000-19:2018(E)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Abbreviated terms . 6
5 Document organization . 6
6 CMAF hypothetical application model, media object model, and profiles .7
6.1 Overview of the hypothetical application model and media object model . 7
6.2 CMAF content processing model . 9
6.3 Late binding CMAF track synchronization .10
6.4 Adaptive switching of CMAF tracks in CMAF switching sets .11
6.5 CMAF specified objects and profiles.12
6.5.1 Object derivation and interoperability code points .12
6.5.2 Encoded media objects . .12
6.5.3 Logical media object sets .12
6.5.4 Addressable media objects .12
6.5.5 CMAF profiles, brand, and identifiers .13
6.6 CMAF media object model .14
6.6.1 CMAF fragments .14
6.6.2 CMAF tracks .15
6.6.3 CMAF track files .15
6.6.4 CMAF segments . .16
6.6.5 CMAF chunks . .16
6.6.6 CMAF switching sets and adaptive switching .17
6.6.7 CMAF selection sets and late binding .20
6.6.8 CMAF presentation timing model .21
6.6.9 Manifest information.23
6.6.10 CMAF addressable media objects, resources, and resource identifiers .24
7 CMAF track format .24
7.1 Overview .24
7.2 CMAF brands.24
7.3 CMAF media objects .25
7.3.1 CMAF boxes .25
7.3.2 CMAF track media objects .28
7.3.3 CMAF addressable media objects .32
7.3.4 CMAF switching sets .34
7.3.5 CMAF selection sets . .37
7.3.6 CMAF presentations .38
7.4 Additional boxes, not defined in the ISO Base Media File Format .38
7.4.1 Track Encryption Box ('tenc') .38
7.4.2 Sample Encryption Box ('senc') .39
7.4.3 Protection System Specific Header Box ('pssh') .39
7.4.4 Media profile specific boxes .39
7.4.5 Event Message Box ('emsg').39
7.5 Constraints on ISO Base Media File Format boxes .40
7.5.1 Movie Header Box ('mvhd') . .40
7.5.2 Metadata Boxes .40
7.5.3 Kind Box ('kind') .40
7.5.4 Track Header Box ('tkhd') .40
7.5.5 Media Header Box ('mdhd') .41
7.5.6 Video Media Header Box ('vmhd') .41
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ISO/IEC 23000-19:2018(E)
7.5.7 Sound Media Header Box ('smhd') .41
7.5.8 Subtitle Media Header Box ('sthd') .41
7.5.9 Data Reference Box ('dref') .42
7.5.10 Sample Description Box ('stsd') .42
7.5.11 Protection Scheme Information Box ('sinf') .42
7.5.12 Track contained media sample information boxes .42
7.5.13 Edit List Box ('elst') .43
7.5.14 Track Extends Box ('trex') .43
7.5.15 Movie Fragment Header Box ('mfhd') .44
7.5.16 Track Fragment Header Box ('tfhd') .44
7.5.17 Track Run Box ('trun') .44
7.5.18 Sample Group Description Box ('sgpd') .45
7.5.19 Media Data Box ('mdat') .45
7.5.20 Sub-sample Information Box ('subs') .45
8 Common Encryption of CMAF tracks .45
8.1 Multiple DRM system support .45
8.2 Track encryption .46
8.2.1 General requirements .46
8.2.2 CMAF track constraints .47
8.2.3 Encryption constraints .48
8.2.4 CMAF presentation encryption .49
9 Video CMAF tracks .49
9.1 Overview .49
9.2 General video CMAF track format .50
9.2.1 General video CMAF track structure and constraints .50
9.2.2 Video Media Header ('vmhd') .50
9.2.3 Track Header Box ('tkhd') .51
9.2.4 Sample Description Box ('stsd') .51
9.2.5 Video CMAF fragment presentation time .52
9.2.6 Video media sample dependencies .52
9.2.7 Video edit lists .52
9.2.8 General video CMAF fragment random access constraints.52
9.2.9 Additional random access pictures within CMAF video fragments .53
9.2.10 Image framing and encoding constraints .53
9.2.11 General video CMAF switching set constraints .53
9.3 NAL structured video CMAF tracks .55
9.3.1 Overview .55
9.3.2 CMAF track format constraints for NAL structured video .55
9.3.3 NAL structured video Access Units contained in media samples .56
9.3.4 NAL structured video coding sequences corresponding to CMAF fragments .56
9.3.5 Elementary stream constraints .57
9.3.6 General CMAF switching set constraints for NAL structured video .57
9.3.7 Single initialization CMAF switching set constraints for NAL structured
video tracks and media profiles .57
9.4 AVC video CMAF tracks .58
9.4.1 Storage of AVC elementary streams .58
9.4.2 Constraints on AVC elementary streams .59
9.5 AVC video Internet Media Type parameters .61
9.5.1 AVC signalling of "codecs" parameters .61
10 Audio CMAF tracks .61
10.1 Overview .61
10.2 General audio CMAF track format .61
10.2.1 Derivation .61
10.2.2 Track Header Box ('tkhd') .61
10.2.3 Sound Media Header Box ('smhd') .62
10.2.4 Sample Description Box ('stsd') .62
10.2.5 AudioSampleEntry .62
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ISO/IEC 23000-19:2018(E)
10.2.6 Audio offset edit list .62
10.3 AAC audio CMAF tracks .62
10.3.1 Overview .62
10.3.2 "codecs" parameter signalling .62
10.3.3 Considerations for AAC audio encoding .63
10.3.4 AAC track constraints .64
10.3.5 AAC elementary stream constraints .65
10.4 AAC core audio CMAF media profile .66
10.5 AAC adaptive switching audio CMAF media profile .67
10.5.1 General constraints .67
10.5.2 CMAF fragment encoding constraints .67
10.5.3 General considerations and requirements .67
10.5.4 Constraints for AAC-LC .68
10.5.5 Constraints for HE-AAC .68
10.5.6 Constraints for HE-AACv2 .69
11 Subtitles and captions .70
11.1 Overview .70
11.2 WebVTT .70
11.3 IMSC text and image tracks .71
11.3.1 General.71
11.3.2 Common constraints .71
11.3.3 IMSC1 text track constraints .71
11.3.4 IMSC1 image track constraints .72
11.4 CTA-608 and CTA-708 .72
11.5 Metadata for subtitles .72
12 CMAF media profiles and CMAF presentation profiles .73
12.1 CMAF media profiles .73
12.1.1 General guidelines for specifying CMAF media profiles .73
12.1.2 Guidelines for audio CMAF media profiles .74
12.1.3 Guidelines for video CMAF media profiles .74
12.2 CMAF presentation profiles .75
12.2.1 General.75
12.2.2 CMAF profile conformance .75
Annex A (normative) CMAF presentation profiles and media profiles.78
Annex B (normative) HEVC video CMAF track format and CMAF media profiles .82
Annex C (informative) Subsampling of NAL structured video tracks in CMAF switching sets .88
Annex D (informative) Hypothetical player model .98
Annex E (informative) Event messages .101
Annex F (informative) Error handling for missing media .102
Annex G (informative) Recommendations for AAC CMAF switching set encoding .103
Bibliography .106
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ISO/IEC 23000-19:2018(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology, SC 29,
Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO/IEC 23000 series can be found on the ISO website.
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ISO/IEC 23000-19:2018(E)
Introduction
Common Media Application Format (CMAF) combines and constrains several MPEG specifications to
define a multimedia format that is optimized for delivery of a single adaptive multimedia presentation to
a variety of devices, using a variety of adaptive streaming, broadcast, download, and storage methods.
Several MPEG specifications have been adopted for much of the video delivered over the Internet and
other IP networks (cellular, cable, broadcast, etc.). Various organizations have taken MPEG’s core coding,
file format and system standards and combined them into their own specifications for their specific
application. While these specifications are similar, their differences result in unnecessary duplication
of engineering effort and duplication of identical content in slightly different formats, which results in
increased storage and delivery costs.
CMAF provides a common media specification that application specifications, such as MPEG Dynamic
Adaptive Streaming over HTTP (DASH), can reference and a common media format that allows a single
encoded multimedia presentation to be used by many applications.
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