ISO/IEC 23000-19:2024/Amd 2

Technologies de l'information — Format pour application multimédia (MPEG-A) — Partie 19: Format CMAF (Common Media Application Format) pour médias segmentés — Amendement 2: Titre manque

General Information

• Status: Not Published
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29/WG 3 - MPEG Systems
• Current Stage: 6000 - International Standard under publication
• Start Date: 12-Jun-2026
• Completion Date: 13-Jun-2026

Relations

• Amends: ISO/IEC 23000-19:2024 - Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media
• Effective Date: 17-Feb-2024

Overview

ISO/IEC 23000-19:2024/Amd 2 is an amendment to the standard for the Common Media Application Format (CMAF) for segmented media, under the broader MPEG-A suite. This amendment introduces an additional structural CMAF brand profile, expanding support for segmented media applications in areas such as adaptive streaming, multimedia archiving, and interoperable delivery of high-quality video and audio. CMAF is widely used for standardized packaging and transport of video, audio, subtitles, and metadata to ensure consistent playback across devices and platforms.

This amendment, developed by ISO/IEC JTC 1/SC 29, builds on established CMAF structures while clarifying and extending profiles to enhance interoperability, metadata handling, and advanced use cases such as multiview and alpha channel video.

Key Topics

• Structural CMAF Brands: Defines additional structural CMAF brand profiles, notably the 'cmf1' brand, which allows for both primary media (video, audio) and supplementary metadata tracks in the same presentation.
• Primary and Supplementary Tracks: Clarifies terminology and requirements for primary media tracks (core playback content) and supplementary metadata tracks (closely linked metadata such as timing or technical information).
• Metadata Handling: Enhances how supplementary metadata is associated with primary media, providing mechanisms for synchronization and track referencing for seamless playback.
• Timed Metadata vs. Supplementary Metadata: Distinction is made between standalone timed metadata tracks and those integrated as supplementary metadata alongside primary content.
• Alpha Channel and Multiview Video Support: Defines profiles for encoding and packaging multiview video (stereoscopic content) and video with alpha channel information, supporting use cases such as immersive media and overlays.
• File Extensions and MIME Types: Updates mappings for track types, file extensions (e.g., .cmfv, .cmfa, .cmfm), and relevant MIME types for improved content identification and delivery.

Applications

The enhancements in this amendment directly benefit:

• Adaptive Streaming Platforms: Improved packaging profiles enable more flexible and efficient delivery of video and audio for HTTP adaptive streaming protocols (e.g., DASH, HLS), supporting advanced media experiences like multi-language tracks or alternate video versions.
• Broadcast and OTT Workflows: Updated brand profiles and metadata support facilitate consistent packaging and playout in broadcast, catch-up TV, and over-the-top (OTT) streaming.
• Multimedia Archiving: Greater support for track references and metadata ensures better cataloging, searchability, and long-term preservation of media assets with all related content and descriptive metadata.
• Augmented and Virtual Reality: Stereoscopic and alpha channel video profiles help enable immersive experiences and interactive overlays, crucial for AR/VR applications.
• Device Interoperability: Due to standardization, consistent playback across devices including smart TVs, mobile devices, and set-top boxes is improved, reducing vendor-specific implementation differences.

Related Standards

• ISO/IEC 23000-19 (CMAF) - The base specification for the Common Media Application Format.
• ISO/IEC 14496-12 (ISO Base Media File Format) - Provides foundational structures for media tracks and metadata, with updates impacting how tracks and fragments are handled.
• ISO/IEC 23008-2 (HEVC) - High Efficiency Video Coding, referenced for handling multiview and alpha video streams.
• IETF RFC 6381 - Codec identification for 'codecs' parameters in streaming and file-based delivery.
• DASH and HLS specifications - While not ISO standards, these widely adopted streaming protocols rely on CMAF-compliant packaging for interoperability.

ISO/IEC 23000-19:2024/Amd 2 delivers expanded structuring and practical tools for content creators, distributors, and developers looking to maximize multimedia compatibility, efficiency, and user experience in segmented media delivery. For further details and technical documentation, refer to the ISO/IEC or national standardization bodies.

Standards Content (Sample)

FINAL DRAFT
Amendment
ISO/IEC
23000-19:2024/
FDAM 2
ISO/IEC JTC 1/SC 29
Information technology —
Secretariat: JISC
Multimedia application format
Voting begins on:
(MPEG-A) —
2026-04-16
Part 19:
Voting terminates on:
2026-06-11
Common media application format
(CMAF) for segmented media
AMENDMENT 2: Additional structural
CMAF brand profile
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/IEC 23000­19:2024/FDAM 2:2026(en) © ISO/IEC 2026

FINAL DRAFT
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
Amendment
ISO/IEC
23000-19:2024/
FDAM 2
ISO/IEC JTC 1/SC 29
Information technology —
Secretariat: JISC
Multimedia application format
Voting begins on:
(MPEG-A) —
Part 19:
Voting terminates on:
Common media application format
(CMAF) for segmented media
AMENDMENT 2: Additional structural
CMAF brand profile
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO/IEC 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/IEC 23000­19:2024/FDAM 2:2026(en) © ISO/IEC 2026

© ISO/IEC 2026 – All rights reserved
ii
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
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.
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 document 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 or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had
not received notice of (a) patent(s) which may be required to implement this document. However,
implementers are cautioned that this may not represent the latest information, which may be obtained from
the patent database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be
held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee
SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO 23000 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.

© ISO/IEC 2026 – All rights reserved
iii
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
Information technology — Multimedia application format
(MPEG-A) —
Part 19:
Common media application format (CMAF) for segmented
media
AMENDMENT 2: Additional structural CMAF brand profile

Clause 3, Terms and definitions
3.2.1
CMAF track
Add the following note:
Note 1 to entry: In addition to a primary media track (3.2.14), the CMAF track can also contain supplementary metadata
tracks (3.2.15).
Add 2 new terms to Clause 3.2:
3.2.14
primary media track
main content track that carries the audio, video, or audiovisual data, essential for the core playback
experience and always present in the MovieBox
3.2.15
supplementary metadata track
metadata track that is directly related to the media data of the primary media track (3.2.14) within the same
CMAF track (3.2.1).
Note 1 to entry: This track uses a handler type equal to 'meta' and provides metadata that enhances or describes the
associated primary media content.

Add 2 new terms to Clause 3.3:
3.3.19
texture picture
picture that carries pixel data corresponding to information that can be rendered on a screen or some other
device, either directly or indirectly after the consideration of additional information, such as alpha, depth,
display, colour format, colour processing, and/or other information that can be associated with such pixel
data
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
3.3.20
alpha picture
picture that contains a video signal representing information indicating the opacity level of each pixel in an
associated foreground picture and how that associated picture should be blended with other pictures for
purposes of alpha blending
Clause 4, Abbreviated terms
Add the following abbreviated terms:
MV multi-view
Clause 7
7.1  Overview
Replace the two paragraphs with the following text:
The CMAF track format is derived from the ISO base media file format in this clause and structural brands
are specified. At this point, the 'cmfc', the 'cmf1', and the 'cmf2' CMAF structural brands are defined. The
'cmf2' brand further restricts the 'cmfc' brand. The 'cmf1' brand both extends and restricts the 'cmfc'
brand.
Several CMAF media objects are derived from the CMAF track format.

7.2
Replace Table 1 with:
Table 1 — CMAF brands
Brand Location Conformance requirements
cmfc
FileTypeBox and SegmentTypeBox 7.6
cmf2
FileTypeBox and SegmentTypeBox 7.7
cmf1
FileTypeBox and SegmentTypeBox 7.8
cmfs SegmentTypeBox
7.3.3.1
cmfl SegmentTypeBox
7.3.3.2
cmff SegmentTypeBox
7.3.2.3
cmfr SegmentTypeBox
7.3.2.4
Replace Table 2 with:
Table 2 — Common media application format file extensions
Track type File extension Internet media type (MIME type)
.cmfv video/mp4
Video
.cmfa audio/mp4
Audio
.cmft application/mp4
Text (subtitle)
.cmfm application/mp4
Metadata
7.3.1
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
th
Replace 4 row of Table 3 with:
ISO/IEC 14496- Container for
trak
+ CMAF 7.5.21
12 each track
nd
Replace 32 row of Table 3 with:
ISO/IEC 14496- Track extends
trex
+ CMAF 7.5.14
12 box
th
Replace 7 row of Table 5 with:
ISO/IEC 14496-
traf
+ CMAF 7.5.21 Track fragment
7.3.2.1
Replace the bullet point c)4) with:
4) The MovieBox shall contain exactly one primary media track containing media data as specified in
subclause 7.3.2.2.
NOTE Timed metadata tracks can be provided as separate CMAF timed metadata tracks in a separate
selection set. Alternatively, supplementary metadata tracks can be included in the same CMAF selection set.

7.3.2.2
Replace the bullet point d with:
d) Each CMAF track contains a single primary media track and TrackBox for the media data, as determined
by the CMAF header constraints specified in subclause 7.3.2.1. A CMAF track can contain additional
TrackBoxes if it carries supplementary metadata tracks.

7.3.2.3
Replace the bullet points b), c) and f) with:
b) The MovieFragmentBox shall conform to the constraints of the structural CMAF brand constraints
specified in Table 5 and clause 7.5.21. The MovieFragmentBox shall contain only one TrackFragmentBox of
the primary media track and can contain TrackFragmentBoxes of the supplementary metadata tracks.
c) The MediaDataBox shall contain all media samples referenced by the TrackRunBox. The MediaDataBox
should follow the TrackRunBox in byte order unless another TrackFragmentBox follows within the
same MovieFragmentBox. If multiple TrackFragmentBoxes are present within a MovieFragmentBox, the
MediaDataBox shall follow the last TrackFragmentBox in that MovieFragmentBox, ensuring all samples
referenced by the TrackRunBoxes are contained in the corresponding MediaDataBox.
f) A CMAF chunk shall contain a TrackFragmentBaseMediaDecodeTimeBox containing the
baseMediaDecodeTime of the first media sample.

7.3.3.3
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
Replace the bullet points d) and e) with:
d) A CMAF track can use an offset edit list as specified in subclauses 7.5.13, 10.2.6 and 9.2.7.
e) A video CMAF track can use version 1 TrackRunBoxes using negative composition offsets to adjust
the composition time of the earliest presented video media sample in each CMAF fragment to its
baseMediaDecodeTime and the earliest video media sample in the CMAF track file to zero, without using
an offset edit list.
7.5.14
Replace the entire text with:
At least one TrackExtendsBox shall be present in a CMAF track since it is a fragmented file as defined in
ISO/IEC 14496-12.
7.5.21
Add a new subclause:
7.5.21  Constraints on the number of tracks in a single CMAF track
A single primary media track shall always be present in a CMAF track.
Additional supplementary metadata tracks can be present, and if present, shall use the track reference box
with at least one track reference type box that describes the association of the supplementary metadata
track to the primary media track. If a specific track reference type is not defined to link the metadata track
to the primary media track it describes, the 'cdsc' track reference type should be used.

7.6
Replace the entire text with:
A CMAF track conforming to the CMAF structural brand 'cmfc' shall conform to the CMAF track constraints
defined in subclauses 7.1, 7.2, 7.3, 7.4, and 7.5. In addition, no supplementary metadata tracks shall be present.

7.7.2
Replace both paragraphs with:
For video CMAF tracks that are not video CMAF track files, the EditBox and, in particular, the EditListBox
shall not be present.
For other CMAF tracks and for video CMAF track files as well as any other media types, the EditListBox can
be present following the constraints in subclause 7.5.13.

7.8
Add a new subclause, 7.8.
7.8  The structural CMAF brand 'cmf1'
7.8.1  General
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
A CMAF track conforming to the CMAF structural brand 'cmf1' shall conform to constraints defined in
subclauses 7.1, 7.2, 7.3, 7.4, and 7.5 and all remaining constraints and exceptions in this clause 7.8. These
constraints are introduced to ensure that the CMAF tracks and CMAF switching set track headers are
conforming, including the case where all CMAF tracks of the presentation conforming to this brand would be
included in a single ISO BMFF file, as well as use cases where supplementary metadata is carried alongside
primary media data within the same CMAF track.
7.8.2  Movie box ('moov')
The MovieBox shall contain exactly one TrackBox of the primary media track and can contain one or more
additional TrackBoxes of supplementary metadata track(s) with closely associated metadata.
7.8.3  Track header box ('tkhd')
CMAF TrackHeaderBoxes shall conform to subclause 7.5.4 with the following additional constraints.
— The MovieFragmentBox shall contain exactly one TrackFragmentBox of the primary media track and may
contain one or more additional TrackFragmentBox of supplementary metadata track(s) with closely
associated metadata.
— If all CMAF tracks of the CMAF presentation are combined into a single ISO BMFF container, then the
track header shall be valid. This for example included that:
— The track_ID is set to a unique identifier over within this CMAF presentation.
— All tracks within one CMAF switching set have alternate_group shall be set to the same value. Each
CMAF switching set in the CMAF presentation shall have a unique value for the alternate_group.
— For a video track, every decoder output signal shall have its decoded and cropped image size in video
spatial samples measured on a uniformly sampled square grid identical to the value of width and height
defined in the track header.
7.8.4  Track reference box ('tref')
The TrackReferenceBox shall be present only in supplementary metadata tracks and shall contain a single
TrackReferenceTypeBox specifying its relation to the corresponding primary media track.
7.8.5  Media header box ('mdhd')
CMAF MediaHeaderBoxes shall conform to 7.5.5 with the following additional constraints.
— If one or more supplementary metadata track(s) are present, the value of the timescale should be the
same as set in the primary media track.
7.8.6  Track fragment decode time box ('tfdt')
The value of the baseMediaDecodeTime in the TrackFragmentBaseMediaDecodeTimeBox of a supplementary
metadata track should be set to the same value as the baseMediaDecodeTime in the TrackFragmentBaseMedia
DecodeTimeBox of the corresponding primary media track.
7.8.7  Duration consistency
The duration of a supplementary metadata track should match the duration of the corresponding
primary media track within a CMAF track. The sum of sample durations in the TrackRunBox elements of a
supplementary metadata track should be equal to the sum of sample durations in the TrackRunBox elements
of the corresponding primary media track.
7.8.8  Metadata track switching and presence in CMAF fragments
Supplementary metadata tracks, when present, shall also be present in each CMAF fragment of a CMAF
track. The boundaries of supplementary metadata tracks shall align with the boundaries of the primary
media track within a CMAF track to allow seamless switching at CMAF fragment boundaries. This ensures

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)
consistent availability of metadata across all fragments and enables adaptive switching without playback
interruptions.
9.2.3
Replace the following bullet point in 9.2.3
— flags = 0x000007
with:
— flags = 0x000007. This value implies that track_enabled, track_in_movie, and track_in_preview are set
to 1; the track_in_preview flag was deprecated in ISOBMFF.

9.2.4
Add the following bullet point at the end of 9.2.4 (before the note):
— one or more ColourInformationBoxes with sub-type 'nclx' as specified in ISO/IEC 14496-12.

9.3.2
Remove the following bullet point from 9.3.2.1:
— The CleanApertureBox should not be present, since the cropped aperture is defined to be active image
(“clean”) in a video CMAF track.

9.3.2.2
Replace:
NOTE 1 The size of the NAL header length field defined in video tracks conforming to ISO/IEC 14496-15 is stored
in the field LengthSizeMinusOne in the corresponding decoder configuration record, e.g. for AVC video in the
AVCDecoderConfigurationRecord.
— shall contain one or more ColorInformationBoxes with sub-type 'nclx' and a PixelAspectRatioBox
'pasp', as documented in ISO/IEC 14496-12, if the first sample entry contains no SPS NAL with VUI in
the decoder configuration record.
NOTE 2 A decoder configuration record without a parameter set is valid for a sample description such as 'avc3' or
'hev1' that can store the parameter set NALs necessary for decoding and display in each CMAF fragment.
with:
NOTE 1 The size of the NAL header length field defined in video tracks conforming to ISO/IEC 14496-15 is stored
in the field LengthSizeMinusOne in the corresponding decoder configuration record, e.g. for AVC video in the
AVCDecoderConfigurationRecord.
NOTE 2 A decoder configuration record without a parameter set is valid for a sample description such as 'avc3' or
'hev1' that can store the parameter set NALs necessary for decoding and display in each CMAF fragment.
— shall contain one or more ColourInformationBoxes with sub-type 'nclx' and a PixelAspectRatioBox
'pasp', as documented in ISO/IEC 14496-12, if the first sample entry contains no SPS NAL unit with a
VUI in the decoder configuration record.
— should not contain a CleanApertureBox, since the cropped aperture is defined to be active image (“clean”)
in a video CMAF track.
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAM 2:2026(en)

9.3.7
Replace bullet c) 2) with:
2) can contain a sample entry without NAL units that shall include one or more ColourInformationBoxes
with sub-type 'nclx' and a PixelAspectRatioBox, as specified in ISO/IEC 14496-12.

9.6
Add the following bullet points at the end of the clause:
— Annex O specifies packaging and codec constraints for some CMAF media profiles using the LCEVC video
codec. Systems claiming conformance to CMAF using LCEVC shall conform to the provisions of Annex O.
— Annex P specifies packaging and codec constraints for some CMAF media profiles using the MV-HEVC
video codec. Systems claiming conformance to CMAF using MV-HEVC shall conform to the provisions of
Annex P.
Clause 13
Change the title and the entire contents of Clause 13 to:
13  CMAF timed metadata tracks
CMAF timed metadata tracks carry information relating to the CMAF presentation, such as programme
metadata or geo-location information. It is important to clarify that the CMAF timed metadata tracks are
distinct from supplementary metadata tracks, as defined in 3.2.15 of this document. While supplementary
metadata tracks are carried within the same CMAF track as the primary media track and maintain a one-
to-one dependency with the media data, CMAF timed metadata tracks are standalone metadata tracks.
These tracks contain a single TrackBox in a MovieBox and are intended to carry general timed metadata
independently.
CMAF timed metadata tracks shall conform to timed metadata tracks as defined in ISO/IEC 14496-12:2022,
12.3, and shall adhere to the CMAF track structure defined in Clause 7 of this document. MetaDataSampleEntry
is used to declare the type of metadata in the track. The URIMetaSampleEntry is one example of a metadata
sample entry that can be used to signal a specific timed metadata sche
...

ISO/IEC 23000-19:2024/DAMFDAmd 2:2025(en)
ISO/IEC JTC 1/SC 29
Secretariat: JISC
Date: 2025-10-252026-04-02
Information technology — Multimedia application format (MPEG-A)
— —
Part 19:
Common media application format (CMAF) for segmented media —
Amendment
AMENDMENT 2: Additional structural CMAF brand profile
FDIS stage
ISO/IEC 23000-19:2024/FDAmd 2(en)
© ISO/IEC 20252026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO'sISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CP 401 • Ch. de Blandonnet 8
CH-12111214 Vernier, Geneva 20
Tel.Phone: + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail: [e-mail]
Web www.iso.org
Website: www.iso.org
Published in Switzerland.
© ISO/IEC 2026 – All rights reserved
ii
ISO/IEC 23000-19:2024/DAMFDAmd 2:2025(en)
Foreword
ISO (the International Organization for Standardization) is a and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide federation of national standardsstandardization.
National bodies (that are members of ISO member bodies). The workor IEC participate in the development of
preparing International Standards is normally carried out through ISO technical committees. Each member
body interested in a subject for which a technical committee has been established has the right to be
represented on that committee. Internationalby 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.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directiveswww.iso.org/directives or
www.iec.ch/members_experts/refdocs).
ISO drawsand IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO takesand IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC [had/had
not] received notice of (a) patent(s) which may be required to implement this document. However,
implementers are cautioned that this may not represent the latest information, which may be obtained from
the patent database available at www.iso.org/patents. ISOwww.iso.org/patents and https://patents.iec.ch.
ISO and IEC shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html)
see www.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-standards.
This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee
SC 29, Coding of audio, picture, multimedia and hypermedia information.
A list of all parts in the ISO 23000 series can be found on the ISO websiteand IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html and
www.iec.ch/national-committees.
© ISO/IEC 2025 2026 – All rights reserved
iii
ISO/IEC 23000-19:2024/DAM 2:2025(en)
Information technology — Multimedia application format (MPEG-A)
— —
Part 19:
Common media application format (CMAF) for segmented media —
Amendment
AMENDMENT 2: Additional structural CMAF brand profile

Clause 3, Terms and definitions
3.2.1
CMAF track
Add the following note:
Note 1 to entry: In addition to a primary media track (3.2.14),(0), the CMAF track can also contain supplementary
metadata tracks (3.2.15).(0).
Add 2 new terms to Clause 3.2:
3.2.14
primary media track
main content track that carries the audio, video, or audiovisual data, essential for the core playback experience
and always present in the MovieBox
3.2.15
supplementary metadata track
metadata track that is directly related to the media data of the primary media track (3.2.14) within the same
CMAF track (3.2.1).
NOTE Note 1 to entry: This track uses a handler type equal to 'meta' and provides metadata that enhances or describes
the associated primary media content.

Add 2 new terms to Clause 3.3:
3.3.19
texture picture
picture that carries pixel data corresponding to information that can be rendered on a screen or some other
device, either directly or indirectly after the consideration of additional information, such as alpha, depth,
display, colour format, colour processing, and/or other information that can be associated with such pixel data
© ISO/IEC 2025 – All rights reserved
ISO/IEC 23000-19:2024/FDAmd 2(en)
3.3.20
alpha picture
picture that contains a video signal representing information indicating the opacity level of each pixel in an
associated foreground picture and how that associated picture should be blended with other pictures for
purposes of alpha blending
Clause 4, Abbreviated terms
Add the following abbreviated terms:
MV multi-view
Inserted Cells
Clause 7
7.1  Overview
Replace the two paragraphs with the following text:
The CMAF track format is derived from the ISO base media file format in this clause and structural brands are
specified. At this point, the 'cmfc', the 'cmf1', and the 'cmf2' CMAF structural brands are defined. The
'cmf2' brand further restricts the 'cmfc' brand. The 'cmf1' brand both extends and restricts the 'cmfc'
brand.
Several CMAF media objects are derived from the CMAF track format.

7.2
Replace Table 1 with:
Table 1 — CMAF brands
Brand Location Conformance requirements
cmfc
FileTypeBox and SegmentTypeBox 7.6
cmf2
FileTypeBox and SegmentTypeBox 7.7
cmf1
FileTypeBox and SegmentTypeBox 7.8
cmfs SegmentTypeBox
7.3.3.1
cmfl SegmentTypeBox 7.3.3.2
cmff SegmentTypeBox
7.3.2.3
cmfr SegmentTypeBox
7.3.2.4
Replace Table 2 with:
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/DAMFDAmd 2:2025(en)
Table 2 — Common media application format file extensions
Track type File extension Internet media type (MIME type)
.cmfv video/mp4
Video
.cmfa audio/mp4
Audio
Text (subtitle) .cmft application/mp4
.cmfm application/mp4
Metadata
7.3.1
th
Replace 4 row of Table 3 with:

Container
ISO/IEC CMAF
trak
+ for each
14496-12 7.5.21
track
nd
Replace 32 row of Table 3 with:

ISO/IEC CMAF Track
trex
+
14496-12 7.5.14 extends box
th
Replace 7 row of Table 5 with:

ISO/IEC CMAF Track
traf     +
14496-12 7.5.21 fragment
7.3.2.1
Replace the bullet point c)4) with:
4) 4) The MovieBox shall contain exactly one primary media track containing media data as
specified in subclause 7.3.2.2.
NOTE Timed metadata tracks can be provided as separate CMAF timed metadata tracks in a separate selection
set. Alternatively, supplementary metadata tracks can be included in the same CMAF selection set.

7.3.2.2
© ISO/IEC 2025 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAmd 2(en)
Replace the bullet point d with:
d) d) Each CMAF track contains a single primary media track and TrackBox for the media data, as
determined by the CMAF header constraints specified in subclause 7.3.2.1. A CMAF track can contain
additional TrackBoxes if it carries supplementary metadata tracks.

7.3.2.3
Replace the bullet points b), c) and f) with:
b) b) The MovieFragmentBox shall conform to the constraints of the structural CMAF brand
constraints specified in Table 5 and clause 7.5.21. The MovieFragmentBox shall contain only one
TrackFragmentBox of the primary media track and can contain TrackFragmentBoxes of the
supplementary metadata tracks.
c) c) The MediaDataBox shall contain all media samples referenced by the TrackRunBox. The
MediaDataBox should follow the TrackRunBox in byte order unless another TrackFragmentBox
follows within the same MovieFragmentBox. If multiple TrackFragmentBoxes are present within a
MovieFragmentBox, the MediaDataBox shall follow the last TrackFragmentBox in that
MovieFragmentBox, ensuring all samples referenced by the TrackRunBoxes are contained in the
corresponding MediaDataBox.
d) f) A CMAF chunk shall contain a TrackFragmentBaseMediaDecodeTimeBox containing the
baseMediaDecodeTime of the first media sample.

7.3.3.3
Replace the bullet points d) and e) with:
d) d) A CMAF track can use an offset edit list as specified in subclauses 7.5.13, 10.2.6 and 9.2.7.
e) e) A video CMAF track can use version 1 TrackRunBoxes using negative composition offsets to
adjust the composition time of the earliest presented video media sample in each CMAF fragment to its
baseMediaDecodeTime and the earliest video media sample in the CMAF track file to zero, without
using an offset edit list.
7.5.14
Replace the entire text with:
At least one TrackExtendsBox shall be present in a CMAF track since it is a fragmented file as defined in
ISO/IEC 14496-12.
7.5.21
Add a new subclause:
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/DAMFDAmd 2:2025(en)
7.5.21  Constraints on the number of tracks in a single CMAF track
A single primary media track shall always be present in a CMAF track.
Additional supplementary metadata tracks can be present, and if present, shall use the track reference box
with at least one track reference type box that describes the association of the supplementary metadata track
to the primary media track. If a specific track reference type is not defined to link the metadata track to the
primary media track it describes, the 'cdsc' track reference type should be used.

7.6
Replace the entire text with:
A CMAF track conforming to the CMAF structural brand 'cmfc' shall conform to the CMAF track constraints
defined in subclauses 7.1, 7.2, 7.3, 7.4, and 7.5. In addition, no supplementary metadata tracks shall be present.

7.7.2
Replace both paragraphs with:
For video CMAF tracks that are not video CMAF track files, the EditBox and, in particular, the EditListBox
shall not be present.
For other CMAF tracks and for video CMAF track files as well as any other media types, the EditListBox
can be present following the constraints in subclause 7.5.13.

7.8
Add a new subclause, 7.8.
7.8  The structural CMAF brand 'cmf1'
7.8.1  General
A CMAF track conforming to the CMAF structural brand 'cmf1' shall conform to constraints defined in
subclauses 7.1, 7.2, 7.3, 7.4, and 7.5 and all remaining constraints and exceptions in this clause 7.8. These
constraints are introduced to ensure that the CMAF tracks and CMAF switching set track headers are
conforming, including the case where all CMAF tracks of the presentation conforming to this brand would be
included in a single ISO BMFF file, as well as use cases where supplementary metadata is carried alongside
primary media data within the same CMAF track.
7.8.2  Movie box ('moov')
The MovieBox shall contain exactly one TrackBox of the primary media track and can contain one or more
additional TrackBoxes of supplementary metadata track(s) with closely associated metadata.
7.8.3  Track header box ('tkhd')
CMAF TrackHeaderBoxes shall conform to subclause 7.5.4 with the following additional constraints.
© ISO/IEC 2025 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAmd 2(en)
— — The MovieFragmentBox shall contain exactly one TrackFragmentBox of the primary media track
and may contain one or more additional TrackFragmentBox of supplementary metadata track(s) with
closely associated metadata.
— — If all CMAF tracks of the CMAF presentation are combined into a single ISO BMFF container, then the
track header shall be valid. This for example included that:
— — The track_ID is set to a unique identifier over within this CMAF presentation.
— — All tracks within one CMAF switching set have alternate_group shall be set to the same value.
Each CMAF switching set in the CMAF presentation shall have a unique value for the alternate_group.
— — For a video track, every decoder output signal shall have its decoded and cropped image size in video
spatial samples measured on a uniformly sampled square grid identical to the value of width and height
defined in the track header.
7.8.4  Track reference box ('tref')
The TrackReferenceBox shall be present only in supplementary metadata tracks and shall contain a single
TrackReferenceTypeBox specifying its relation to the corresponding primary media track.
7.8.5  Media header box ('mdhd')
CMAF MediaHeaderBoxes shall conform to 7.5.5 with the following additional constraints.
— — If one or more supplementary metadata track(s) are present, the value of the timescale should be
the same as set in the primary media track.
7.8.6  Track fragment decode time box ('tfdt')
The value of the baseMediaDecodeTime in the TrackFragmentBaseMediaDecodeTimeBox of a
supplementary metadata track should be set to the same value as the baseMediaDecodeTime in the
TrackFragmentBaseMediaDecodeTimeBox of the corresponding primary media track.
7.8.7  Duration consistency
The duration of a supplementary metadata track should match the duration of the corresponding primary
media track within a CMAF track. The sum of sample durations in the TrackRunBox elements of a
supplementary metadata track should be equal to the sum of sample durations in the TrackRunBox elements
of the corresponding primary media track.
7.8.8  Metadata track switching and presence in CMAF fragments
Supplementary metadata tracks, when present, shall also be present in each CMAF fragment of a CMAF track.
The boundaries of supplementary metadata tracks shall align with the boundaries of the primary media track
within a CMAF track to allow seamless switching at CMAF fragment boundaries. This ensures consistent
availability of metadata across all fragments and enables adaptive switching without playback interruptions.

9.2.3
Replace the following bullet point in 9.2.3
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/DAMFDAmd 2:2025(en)
— — flags = 0x000007
with:
— — flags = 0x000007. This value implies that track_enabled, track_in_movie, and
track_in_preview are set to 1; the track_in_preview flag was deprecated in ISOBMFF.

9.2.4
Add the following bullet point at the end of 9.2.4 (before the note):
— — one or more ColourInformationBoxes with sub-type 'nclx' as specified in ISO/IEC 14496-12.

9.3.2
Remove the following bullet point from 9.3.2.1:
— — The CleanApertureBox should not be present, since the cropped aperture is defined to be active
image (“clean”) in a video CMAF track.

9.3.2.2
Replace:
NOTE 1 The size of the NAL header length field defined in video tracks conforming to ISO/IEC 14496-15 is stored in
the field LengthSizeMinusOne in the corresponding decoder configuration record, e.g. for AVC video in the
AVCDecoderConfigurationRecord.
— — shall contain one or more ColorInformationBoxes with sub-type 'nclx' and a
PixelAspectRatioBox 'pasp', as documented in ISO/IEC 14496-12, if the first sample entry
contains no SPS NAL with VUI in the decoder configuration record.
NOTE 2 A decoder configuration record without a parameter set is valid for a sample description such as 'avc3' or
'hev1' that can store the parameter set NALs necessary for decoding and display in each CMAF fragment.
with:
NOTE 1 The size of the NAL header length field defined in video tracks conforming to ISO/IEC 14496-15 is stored in
the field LengthSizeMinusOne in the corresponding decoder configuration record, e.g. for AVC video in the
AVCDecoderConfigurationRecord.
NOTE 2 A decoder configuration record without a parameter set is valid for a sample description such as 'avc3' or
'hev1' that can store the parameter set NALs necessary for decoding and display in each CMAF fragment.
— — shall contain one or more ColourInformationBoxes with sub-type 'nclx' and a
PixelAspectRatioBox 'pasp', as documented in ISO/IEC 14496-12, if the first sample entry
contains no SPS NAL unit with a VUI in the decoder configuration record.
© ISO/IEC 2025 2026 – All rights reserved
ISO/IEC 23000-19:2024/FDAmd 2(en)
— — should not contain a CleanApertureBox, since the cropped aperture is defined to be active image
(“clean”) in a video CMAF track.

9.3.7
Replace bullet c) 2) with:
2) 2) can contain a sample entry without NAL units that shall include one or more
ColourInformationBoxes with sub-type 'nclx' and a PixelAspectRatioBox, as specified in
ISO/IEC 14496-12.
9.6
Add the following bullet points at the end of the clause:
— — Annex O specifies packaging and codec constraints for some CMAF media profiles using the LCEVC
video codec. Systems claiming conformance to CMAF using LCEVC shall conform to the provisions of
Annex O.
— — Annex P specifies packaging and codec constraints for some CMAF media profiles using the MV-HEVC
video codec. Systems claiming conformance to CMAF using MV-HEVC shall conform to the provisions of
Annex P.
Clause 13
Change the title and the entire contents of Clause 13 to:
13  CMAF timed metadata tracks
CMAF timed metadata tracks carry information relating to the CMAF presentation, such as programme
metadata or geo-location information. It is important to clarify that the CMAF timed metadata tracks are
distinct from supplementary metadata tracks, as defined in 3.2.15 of this document. While supplementary
metadata tracks are carried within the same CMAF track as the primary media track and maintain a one-to-
one dependency with the media data, CMAF timed metadata tracks are standalone metadata tracks. These
tracks contain a single TrackBox in a MovieBox and are intended to carry general timed metadata
independently.
CMAF timed metadata tracks shall conform to timed metadata tracks as defined in ISO/IEC 14496-12:2022,
12.3, and shall adhere to the CMAF track structure defined in Clause 7 of this document.
MetaDataSampleEntry is used to declare the type of metadata in the track. The URIMetaSampleEntry
is one example of a metadata sample entry that can be used to signal a specific timed metadata scheme via a
URI in URIBox.
Each ISO BMFF sample in a CMAF timed metadata track encloses metadata relevant to the presentation
interval of that sample as defined in ISO/IEC 14496-12.
Metadata applying to other intervals can be present if this is supported by a metadata scheme, however such
metadata should also be carried in an ISO BMFF sample with an overlapping presentation time interval (if
© ISO/IEC 2026 – All rights reserved
ISO/IEC
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