ISO/IEC 23000-19:2024/Amd 2:2026

• Status: Published
• Publication Date: 26-Jul-2026
• 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: 6060 - International Standard published
• Start Date: 27-Jul-2026
• Due Date: 08-Feb-2027
• Completion Date: 27-Jul-2026

• 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

ISO/IEC 23000-19:2024/Amd. 2:2026 is an ISO and IEC amendment to MPEG-A Part 19, the Common media application format (CMAF) for segmented media. It adds an additional structural CMAF brand profile and updates track, metadata, and codec-profile rules for systems that package, signal, and play CMAF media.

What does ISO/IEC 23000-19:2024/Amd. 2:2026 specify?

ISO/IEC 23000-19:2024/Amd. 2:2026 specifies how CMAF tracks can carry a primary media track together with supplementary metadata tracks, and it defines how several CMAF structural brands constrain the file layout. It also adds timed metadata tracks and profile-specific constraints for HEVC, LCEVC, and MV-HEVC use cases.

The amendment is organized around:

• Clause 3 - terms and definitions
• Clause 4 - abbreviated terms
• Clause 7 - CMAF track format and structural brands
• Clause 9 - video track and sample-entry constraints
• Clause 13 - CMAF timed metadata tracks
• Annexes B, H, O, and P - codec and profile-specific constraints

Annex	What it covers
Annex B	HEVC video tracks and HEVC-based CMAF media profiles
Annex H	Dependent CMAF tracks
Annex O	LCEVC packaging and codec constraints
Annex P	MV-HEVC track and media profiles, including stereo and alpha variants

What are the key requirements of ISO/IEC 23000-19:2024/Amd. 2:2026?

ISO/IEC 23000-19:2024/Amd. 2:2026 tightens the CMAF track structure in Clause 7 and adds new profile rules in Clause 13 and the annexes. In practice, the document is mainly about what boxes, tracks, and sample-entry features are allowed together, and how metadata and video layers must line up.

Structural CMAF brands and track layout

• Clause 7.1 and 7.2 define the structural brands 'cmfc', 'cmf2', and 'cmf1'. 'cmf2' further restricts 'cmfc', while 'cmf1' both extends and restricts it. This matters because the brand in FileTypeBox and SegmentTypeBox tells receivers what they may expect in the file.
• Clause 7.3.2.1 and 7.3.2.2 require exactly one primary media track in the MovieBox. Supplementary metadata tracks may also be present, which lets one CMAF track carry media and closely linked metadata together.
• Clause 7.3.2.3 and 7.5.21 require supplementary metadata tracks to be linked to the primary media track with track references, using 'cdsc' when no more specific reference type is defined. This gives players a clear relationship between media and metadata.
• Clause 7.5.14 requires at least one TrackExtendsBox because CMAF is a fragmented file. That is the fragment-level signaling a packager must include.

Brand-specific constraints

• Clause 7.6 says a 'cmfc' CMAF track follows the general CMAF track constraints but cannot contain supplementary metadata tracks. That makes 'cmfc' the simpler, media-only structural brand.
• Clause 7.8 defines 'cmf1' for cases where supplementary metadata is carried with the primary media track. It also adds rules for TrackHeaderBox, TrackReferenceBox, timescale, decode time, duration matching, and fragment alignment so metadata stays synchronized with the media.
• Clause 13 defines CMAF timed metadata tracks as standalone metadata tracks, separate from supplementary metadata tracks. They use one TrackBox in the MovieBox, all samples are sync samples, and the track file can use the '.cmfm' extension.

Video and codec signaling

• Clause 9 updates color and pixel-aspect signaling for video tracks, including 'nclx' ColourInformationBoxes and, in some cases, a PixelAspectRatioBox. That matters when a track must describe color and display shape without relying on sample content alone.
• Clause 9 also updates video edit-list and fragment timing rules, including how baseMediaDecodeTime is handled. This affects switching and consistent playback across fragments.
• Annex O states that CMAF systems using LCEVC shall follow the Annex O packaging and codec constraints, and Annex P does the same for MV-HEVC. That is where the profile-specific signaling and layer rules are concentrated.

What terms does ISO/IEC 23000-19:2024/Amd. 2:2026 define?

• CMAF track - A CMAF track is the track-level packaging unit that carries media and, where allowed, associated metadata.
• primary media track - The primary media track is the main audio, video, or audiovisual track, and it is always present in the MovieBox.
• supplementary metadata track - A supplementary metadata track is metadata directly related to the primary media track inside the same CMAF track.
• CMAF timed metadata track - A CMAF timed metadata track is a standalone metadata track for presentation-related information such as programme metadata or geo-location information.
• texture picture - A texture picture is pixel data intended to be rendered on a screen or another device, directly or with extra interpretation.
• alpha picture - An alpha picture carries opacity information used for alpha blending with another picture.
• MV - MV means multi-view.

Who uses ISO/IEC 23000-19:2024/Amd. 2:2026?

ISO/IEC 23000-19:2024/Amd. 2:2026 is used by engineers and vendors who author, package, validate, or play CMAF content. It is relevant to streaming platform teams, player developers, codec and packager suppliers, and quality or conformance teams working with segmented media, timed metadata, LCEVC, HEVC, or MV-HEVC.

What changed in ISO/IEC 23000-19:2024/Amd. 2:2026 from the previous edition?

ISO/IEC 23000-19:2024/Amd. 2:2026 adds:

• the new terms primary media track, supplementary metadata track, texture picture, and alpha picture
• the abbreviated term MV
• updated brand text for 'cmfc', 'cmf2', 'cmf1', and the other CMAF brands listed in Table 1
• new rules for supplementary metadata tracks inside CMAF tracks
• a full Clause 13 on CMAF timed metadata tracks
• updated HEVC-related text in Annex B and dependent-track text in Annex H
• updated LCEVC constraints in Annex O
• a new normative Annex P for MV-HEVC profiles, including 'mvst', 'hval', and 'mvsa'

Which standards are used with ISO/IEC 23000-19:2024/Amd. 2:2026?

• ISO/IEC 14496-12:2022 - Provides the ISO base media file format structures used for CMAF boxes, tracks, fragments, edit lists, and timed metadata tracks.
• ISO/IEC 14496-15:2024 - Provides the video sample entry and decoder-configuration structures used for HEVC and layered HEVC signaling.
• ISO/IEC 23008-2 - Provides the HEVC and MV-HEVC coding rules, including the profile and SEI-message constraints used in Annexes B and P.
• IETF RFC 6381 - Provides the codec string syntax used to signal profile and level information.

What does the ISO/IEC 23000-19:2024/Amd. 2:2026 document contain?

This amendment contains updated tables for CMAF brands, file extensions, and box mappings, including the brand table in Clause 7 and the file-extension table for video, audio, text, and metadata tracks. It also contains detailed constraints for MovieBox, MovieFragmentBox, TrackHeaderBox, TrackReferenceBox, sample-entry signaling, and fragment timing.

The annexes add profile-specific packaging rules and codec constraints for HEVC, LCEVC, and MV-HEVC, including the profile overview table in Annex P and the codec-parameter tables in Annex O. These parts are used when designing packagers, checking interoperable track structures, and validating conformance of CMAF media and switching sets.

International
Standard
ISO/IEC 23000-19
Third edition
Information technology —
2024-02
Multimedia application format
(MPEG-A) —
AMENDMENT 2
2026-07
Part 19:
Common media application format
(CMAF) for segmented media
AMENDMENT 2: Additional structural
CMAF brand profile
Reference number
ISO/IEC 23000-19:2024/Amd. 2:2026(en) © ISO/IEC 2026

ISO/IEC 23000-19:2024/Amd. 2:2026(en)
© ISO/IEC 2026
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© ISO/IEC 2026 – All rights reserved
ii
ISO/IEC 23000-19:2024/Amd. 2:2026(en)
Foreword
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This document was prepared by Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee
SC 29, Coding of audio, picture, multimedia and hypermedia information.
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© ISO/IEC 2026 – All rights reserved
iii
ISO/IEC 23000-19:2024/Amd. 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/Amd. 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
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/Amd. 2:2026(en)
7.3.1
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.

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/Amd. 2:2026(en)
7.3.3.3
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.
© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/Amd. 2:2026(en)
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.
— 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

© ISO/IEC 2026 – All rights reserved
ISO/IEC 23000-19:2024/Amd. 2:2026(en)
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
— 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 2026 – All rights reserved
ISO/IEC 23000-19:2024/Amd. 2:2026(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) 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
such sample is present). In other words, metadata should be repeated in all samples during which it applies;
otherwise, players can miss metadata in case of random access to the metadata track.
All samples are sync samples. In addition, no knowledge of a prior sample should be required to correctly
interpret the metadata carried in an ISO BMFF sample.
C
...