ISO/IEC 23000-19:2020
Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media
This document 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.
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
3.1 Media objects
3.2 Logical structure
3.3 Application model
4 Abbreviated terms
5 Document organization
6 CMAF hypothetical application model, media object model and profiles
6.1 Overview of the hypothetical application model and media object model
6.2 CMAF content processing model
6.3 Late binding CMAF track synchronization
6.4 Adaptive switching of CMAF tracks in CMAF switching sets
6.5 CMAF specified objects and profiles
6.5.1 Object derivation and interoperability code points
6.5.2 Encoded media objects
6.5.3 Logical media object sets
6.5.4 Addressable media objects
6.5.5 CMAF profiles, brand and identifiers
6.6 CMAF media object model
6.6.1 CMAF fragments
6.6.2 CMAF tracks
6.6.3 CMAF track files
6.6.4 CMAF segments
6.6.5 CMAF chunks
6.6.6 CMAF switching sets and adaptive switching
6.6.7 CMAF selection sets and late binding
6.6.8 CMAF presentation timing model
6.6.9 Manifest information
6.6.10 CMAF addressable media objects, resources, and resource identifiers
7 CMAF track format
7.1 Overview
7.2 CMAF brands
7.3 CMAF media objects
7.3.1 CMAF boxes
7.3.2 CMAF track media objects
7.3.3 CMAF addressable media objects
7.3.4 CMAF switching sets
7.3.5 CMAF selection sets
7.3.6 CMAF presentations
7.4 Additional boxes, not defined in the ISO Base Media File Format
7.4.1 Track Encryption Box ('tenc')
7.4.2 Sample Encryption Box ('senc')
7.4.3 Protection System Specific Header Box ('pssh')
7.4.4 Media profile specific boxes
7.4.5 Event Message Box ('emsg')
7.5 Constraints on ISO Base Media File Format boxes
7.5.1 Movie Header Box ('mvhd')
7.5.2 Metadata Boxes
7.5.3 Kind Box ('kind')
7.5.4 Track Header Box ('tkhd')
7.5.5 Media Header Box ('mdhd')
7.5.6 Video Media Header Box ('vmhd')
7.5.7 Sound Media Header Box ('smhd')
7.5.8 Subtitle Media Header Box ('sthd')
7.5.9 Data Reference Box ('dref')
7.5.10 Sample Description Box ('stsd')
7.5.11 Protection Scheme Information Box ('sinf')
7.5.12 Track contained media sample information boxes
7.5.13 Edit List Box ('elst')
7.5.14 Track Extends Box ('trex')
7.5.15 Movie Fragment Header Box ('mfhd')
7.5.16 Track Fragment Header Box ('tfhd')
7.5.17 Track Run Box ('trun')
7.5.18 Sample Group Description Box ('sgpd')
7.5.19 Media Data Box ('mdat')
7.5.20 Sub-sample Information Box ('subs')
7.6 The Structural CMAF Brand 'cmfc'
7.7 The structural CMAF Brand 'cmf2'
7.7.1 General
7.7.2 Edit List Box ('elst')
7.7.3 Track Run Box ('trun')
8 Common encryption of CMAF tracks
8.1 Multiple DRM system support
8.2 Track encryption
8.2.1 General requirements
8.2.2 CMAF track constraints
8.2.3 Encryption constraints
8.2.4 CMAF presentation encryption
9 Video CMAF tracks
9.1 Overview
9.2 General video CMAF track format
9.2.1 General video CMAF track structure and constraints
9.2.2 Video Media Header ('vmhd')
9.2.3 Track Header Box ('tkhd')
9.2.4 Sample Description Box ('stsd')
9.2.5 Video CMAF fragment presentation time
9.2.6 Video media sample dependencies
9.2.7 Video edit lists
9.2.8 General video CMAF fragment random access constraints
9.2.9 Additional random access pictures within CMAF video fragments
9.2.10 Image framing and encoding constraints
9.2.11 General video CMAF switching set constraints
9.3 NAL structured video CMAF tracks
9.3.1 Overview
9.3.2 CMAF track format constraints for NAL structured video
9.3.3 NAL structured video access units contained in media samples
9.3.4 NAL structured video coding sequences corresponding to CMAF fragments
9.3.5 Elementary stream constraints
9.3.6 General CMAF switching set constraints for NAL structured video
9.3.7 Single initialization CMAF switching set constraints for NAL structured video tracks and media profiles
9.4 AVC video CMAF tracks
9.4.1 Storage of AVC elementary streams
9.4.2 Constraints on AVC elementary streams
9.5 AVC video Internet Media Type parameters
9.5.1 AVC signalling of "codecs" parameters
10 Audio CMAF tracks
10.1 Overview
10.2 General audio CMAF track format
10.2.1 Derivation
10.2.2 Track Header Box ('tkhd')
10.2.3 Sound Media Header Box ('smhd')
10.2.4 Sample Description Box ('stsd')
10.2.5 AudioSampleEntry
10.2.6 Audio offset edit list
10.3 AAC audio CMAF tracks
10.3.1 Overview
10.3.2 "codecs" parameter signalling
10.3.3 Considerations for AAC audio encoding
10.3.4 AAC track constraints
10.3.5 AAC elementary stream constraints
10.4 AAC core audio CMAF media profile
10.5 AAC adaptive switching audio CMAF media profile
10.5.1 General constraints
10.5.2 CMAF fragment encoding constraints
10.5.3 General considerations and requirements
10.5.4 Constraints for AAC-LC
10.5.5 Constraints for HE-AAC
10.5.6 Constraints for HE-AACv2
11 Subtitles and captions
11.1 Overview
11.2 WebVTT
11.3 IMSC text and image tracks
11.3.1 General
11.3.2 Common constraints
11.3.3 IMSC1 text track constraints
11.3.4 IMSC1 image track constraints
11.4 CTA-608 and CTA-708
11.5 Metadata for subtitles
12 CMAF media profiles and CMAF presentation profiles
12.1 CMAF media profiles
12.1.1 General guidelines for specifying CMAF media profiles
12.1.2 Guidelines for audio CMAF media profiles
12.1.3 Guidelines for video CMAF media profiles
12.2 CMAF presentation profiles
12.2.1 General
12.2.2 CMAF profile conformance
Annex A (normative) CMAF presentation profiles, media profiles and supplemental data
Annex B (normative) HEVC video CMAF track format and CMAF media profiles
Annex C (informative) Subsampling of NAL structured video tracks in CMAF switching sets
Annex D (informative) Hypothetical player model
Annex E (informative) Event messages
Annex F (informative) Error handling for missing media
Annex G (informative) Recommendations for AAC CMAF switching set encoding
Annex H (normative) Scalable HEVC media profile and track format
Annex I (normative) AAC multichannel CMAF media profiles and track format
Annex J (normative) MPEG-H 3D audio track format and CMAF media profile
Annex K (normative) MPEG-D USAC track format and CMAF media profile
Annex L (normative) IMSC 1.1 media profiles
Bibliography
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
3.1 Media objects
3.2 Logical structure
3.3 Application model
4 Abbreviated terms
5 Document organization
6 CMAF hypothetical application model, media object model and profiles
6.1 Overview of the hypothetical application model and media object model
6.2 CMAF content processing model
6.3 Late binding CMAF track synchronization
6.4 Adaptive switching of CMAF tracks in CMAF switching sets
6.5 CMAF specified objects and profiles
6.5.1 Object derivation and interoperability code points
6.5.2 Encoded media objects
6.5.3 Logical media object sets
6.5.4 Addressable media objects
6.5.5 CMAF profiles, brand and identifiers
6.6 CMAF media object model
6.6.1 CMAF fragments
6.6.2 CMAF tracks
6.6.3 CMAF track files
6.6.4 CMAF segments
6.6.5 CMAF chunks
6.6.6 CMAF switching sets and adaptive switching
6.6.7 CMAF selection sets and late binding
6.6.8 CMAF presentation timing model
6.6.9 Manifest information
6.6.10 CMAF addressable media objects, resources, and resource identifiers
7 CMAF track format
7.1 Overview
7.2 CMAF brands
7.3 CMAF media objects
7.3.1 CMAF boxes
7.3.2 CMAF track media objects
7.3.3 CMAF addressable media objects
7.3.4 CMAF switching sets
7.3.5 CMAF selection sets
7.3.6 CMAF presentations
7.4 Additional boxes, not defined in the ISO Base Media File Format
7.4.1 Track Encryption Box ('tenc')
7.4.2 Sample Encryption Box ('senc')
7.4.3 Protection System Specific Header Box ('pssh')
7.4.4 Media profile specific boxes
7.4.5 Event Message Box ('emsg')
7.5 Constraints on ISO Base Media File Format boxes
7.5.1 Movie Header Box ('mvhd')
7.5.2 Metadata Boxes
7.5.3 Kind Box ('kind')
7.5.4 Track Header Box ('tkhd')
7.5.5 Media Header Box ('mdhd')
7.5.6 Video Media Header Box ('vmhd')
7.5.7 Sound Media Header Box ('smhd')
7.5.8 Subtitle Media Header Box ('sthd')
7.5.9 Data Reference Box ('dref')
7.5.10 Sample Description Box ('stsd')
7.5.11 Protection Scheme Information Box ('sinf')
7.5.12 Track contained media sample information boxes
7.5.13 Edit List Box ('elst')
7.5.14 Track Extends Box ('trex')
7.5.15 Movie Fragment Header Box ('mfhd')
7.5.16 Track Fragment Header Box ('tfhd')
7.5.17 Track Run Box ('trun')
7.5.18 Sample Group Description Box ('sgpd')
7.5.19 Media Data Box ('mdat')
7.5.20 Sub-sample Information Box ('subs')
7.6 The Structural CMAF Brand 'cmfc'
7.7 The structural CMAF Brand 'cmf2'
7.7.1 General
7.7.2 Edit List Box ('elst')
7.7.3 Track Run Box ('trun')
8 Common encryption of CMAF tracks
8.1 Multiple DRM system support
8.2 Track encryption
8.2.1 General requirements
8.2.2 CMAF track constraints
8.2.3 Encryption constraints
8.2.4 CMAF presentation encryption
9 Video CMAF tracks
9.1 Overview
9.2 General video CMAF track format
9.2.1 General video CMAF track structure and constraints
9.2.2 Video Media Header ('vmhd')
9.2.3 Track Header Box ('tkhd')
9.2.4 Sample Description Box ('stsd')
9.2.5 Video CMAF fragment presentation time
9.2.6 Video media sample dependencies
9.2.7 Video edit lists
9.2.8 General video CMAF fragment random access constraints
9.2.9 Additional random access pictures within CMAF video fragments
9.2.10 Image framing and encoding constraints
9.2.11 General video CMAF switching set constraints
9.3 NAL structured video CMAF tracks
9.3.1 Overview
9.3.2 CMAF track format constraints for NAL structured video
9.3.3 NAL structured video access units contained in media samples
9.3.4 NAL structured video coding sequences corresponding to CMAF fragments
9.3.5 Elementary stream constraints
9.3.6 General CMAF switching set constraints for NAL structured video
9.3.7 Single initialization CMAF switching set constraints for NAL structured video tracks and media profiles
9.4 AVC video CMAF tracks
9.4.1 Storage of AVC elementary streams
9.4.2 Constraints on AVC elementary streams
9.5 AVC video Internet Media Type parameters
9.5.1 AVC signalling of "codecs" parameters
10 Audio CMAF tracks
10.1 Overview
10.2 General audio CMAF track format
10.2.1 Derivation
10.2.2 Track Header Box ('tkhd')
10.2.3 Sound Media Header Box ('smhd')
10.2.4 Sample Description Box ('stsd')
10.2.5 AudioSampleEntry
10.2.6 Audio offset edit list
10.3 AAC audio CMAF tracks
10.3.1 Overview
10.3.2 "codecs" parameter signalling
10.3.3 Considerations for AAC audio encoding
10.3.4 AAC track constraints
10.3.5 AAC elementary stream constraints
10.4 AAC core audio CMAF media profile
10.5 AAC adaptive switching audio CMAF media profile
10.5.1 General constraints
10.5.2 CMAF fragment encoding constraints
10.5.3 General considerations and requirements
10.5.4 Constraints for AAC-LC
10.5.5 Constraints for HE-AAC
10.5.6 Constraints for HE-AACv2
11 Subtitles and captions
11.1 Overview
11.2 WebVTT
11.3 IMSC text and image tracks
11.3.1 General
11.3.2 Common constraints
11.3.3 IMSC1 text track constraints
11.3.4 IMSC1 image track constraints
11.4 CTA-608 and CTA-708
11.5 Metadata for subtitles
12 CMAF media profiles and CMAF presentation profiles
12.1 CMAF media profiles
12.1.1 General guidelines for specifying CMAF media profiles
12.1.2 Guidelines for audio CMAF media profiles
12.1.3 Guidelines for video CMAF media profiles
12.2 CMAF presentation profiles
12.2.1 General
12.2.2 CMAF profile conformance
Annex A (normative) CMAF presentation profiles, media profiles and supplemental data
Annex B (normative) HEVC video CMAF track format and CMAF media profiles
Annex C (informative) Subsampling of NAL structured video tracks in CMAF switching sets
Annex D (informative) Hypothetical player model
Annex E (informative) Event messages
Annex F (informative) Error handling for missing media
Annex G (informative) Recommendations for AAC CMAF switching set encoding
Annex H (normative) Scalable HEVC media profile and track format
Annex I (normative) AAC multichannel CMAF media profiles and track format
Annex J (normative) MPEG-H 3D audio track format and CMAF media profile
Annex K (normative) MPEG-D USAC track format and CMAF media profile
Annex L (normative) IMSC 1.1 media profiles
Bibliography