ISO/IEC 14496-12:2026

Information technology — Coding of audio-visual objects — Part 12: ISO base media file format

This document specifies the ISO base media file format, which is a general format forming the basis for a number of other more specific file formats. This format contains the timing, structure, and media information for timed sequences of media data, such as audio-visual presentations.

Technologies de l'information — Codage des objets audiovisuels — Partie 12: Format ISO de base pour les fichiers médias

General Information

• Status: Published
• Publication Date: 21-Apr-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: 22-Apr-2026
• Due Date: 02-Sep-2025
• Completion Date: 22-Apr-2026

Relations

• Revises: ISO/IEC 14496-12:2022 - Information technology — Coding of audio-visual objects — Part 12: ISO base media file format
• Effective Date: 13-Feb-2026

Overview

ISO/IEC 14496-12:2025 specifies the ISO base media file format - a widely adopted container format in digital media. Developed by ISO/IEC JTC 1/SC 29/WG 11, this standard serves as the foundational structure for a broad range of audio-visual file formats and applications. The ISO base media file format organizes media data into timed sequences, supporting efficient storage, synchronization, and playback of audio-visual presentations. It establishes the timing, structure, and metadata necessary for consistent handling and interoperability of multimedia content across platforms, devices, and services.

Key Topics

• General Structure: The format defines a system of interconnected “boxes” that organize information about media data, such as tracks, timing, and metadata. This modular design supports extensibility and flexibility for diverse applications.
• Timed Media Support: It manages detailed timing information for media samples, enabling synchronized playback of audio, video, and other timed data streams.
• File Organization: Multiple file types are defined, including movie files, segment files, and item files-supporting varied use cases, from streaming to editing and archiving.
• Extensibility: The standard allows for the addition of new “box” types and file format brands, ensuring future-proofing and compatibility with evolving multimedia technologies.
• Metadata Handling: Detailed structures for metadata, including user data, copyright, and track information, provide robust support for content management and interoperability.
• Sample Groups and Hint Tracks: It supports grouping samples for advanced playback scenarios and incorporates hint tracks to facilitate network streaming.

Applications

The ISO base media file format underpins a wide array of multimedia technologies and standards. Its practical applications include:

• Digital Video and Audio: Forms the core container for formats such as MP4 (.mp4), facilitating storage and playback of compressed audio and video streams.
• Broadcast and Streaming: Used extensively in streaming protocols (such as MPEG-DASH and HLS) to enable efficient, adaptive delivery of multimedia over networks.
• Content Editing: Enables non-linear editing systems and tools to efficiently manipulate multimedia files by providing a structured, accessible format.
• Archival and Exchange: Ensures long-term compatibility and interoperability of audio-visual content in digital archives, professional workflows, and cross-platform distribution.
• Rich Metadata Support: Facilitates embedding of extensive metadata, rights information, and user data, supporting robust content management and discovery.

Related Standards

ISO/IEC 14496-12 forms the baseline for many derived and related standards in the digital media domain, including:

• ISO/IEC 14496-14 (MP4 File Format): Specifies the MP4 extension of the base file format for compressed audio-visual data.
• ISO/IEC 14496-15 (AVC File Format): Defines storage of H.264/AVC video within the base file format.
• ISO/IEC 14496-30: Covers carriage of metadata and additional data types.
• MPEG-DASH (ISO/IEC 23009-1): Uses the base media file format for adaptive streaming over HTTP.
• Other Derived Formats: Formats such as 3GPP (.3gp), Motion JPEG 2000 (.mj2), and others extend the ISO base media file format for specific industry requirements.

By defining a unified and extensible structure for timed media data, ISO/IEC 14496-12 ensures seamless multimedia interaction, cross-standard compatibility, and support for innovative audio-visual applications across the information technology landscape.

Standards Content (Sample)

International
Standard
ISO/IEC 14496-12
Eighth edition
Information technology — Coding of
2026-04
audio-visual objects —
Part 12:
ISO base media file format
Technologies de l'information — Codage des objets
audiovisuels —
Partie 12: Format ISO de base pour les fichiers médias
Reference number
© ISO/IEC 2026
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’s member body in the country of the requester.
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
© ISO/IEC 2026 – All rights reserved
ii
Contents Page
Foreword .x
Introduction .xi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions .2
3.2 Abbreviated terms .8
4 ISO base media file organization . 9
4.1 File structure .9
4.2 Binary structure .9
4.2.1 Syntax conventions .9
4.2.2 Box definitions .10
4.2.3 Extensibility of box definitions .11
4.2.4 Data types and fields . 12
5 Typed ISO base media file organization .13
5.1 File structure . 13
5.2 File-type box .14
5.2.1 Definition .14
5.2.2 Syntax . .14
5.2.3 Semantics .14
5.3 Extended type box . . . 15
5.3.1 Definition . 15
5.3.2 Syntax . . 15
5.3.3 Semantics . 15
6 Common specifications for movie files, item files and segment files .16
6.1 Data offsets .16
6.2 Box order .17
7 Movie file organization .21
7.1 Files, segments, and streams .21
7.2 Presentation structure . 22
7.2.1 Box structure of a presentation . 22
7.2.2 Meta data and media data . 22
7.3 Structure-data . 22
7.3.1 Box . . 22
7.3.2 Interpretation of matrix values . 22
7.3.3 URIs as type indicators . . 23
7.3.4 Box order . 23
7.4 Time structure overview .24
7.5 Identifiers .24
7.6 Uniform resource locators (URLs) .24
8 Box structures .25
8.1 File structure and general boxes . 25
8.1.1 Media data box . 25
8.1.2 Free space box . 25
8.1.3 Progressive download information box . 26
8.1.4 Identified media data box . . 26
8.2 Movie structure .27
8.2.1 Movie box .27
8.2.2 Movie header box .27
8.3 Track structure . 29
8.3.1 Track box . 29
8.3.2 Track header box . 29

© ISO/IEC 2026 – All rights reserved
iii
8.3.3 Track reference box.32
8.3.4 Track group box . . 34
8.3.5 Track type box . 36
8.4 Track media structure .37
8.4.1 Media box .37
8.4.2 Media header box .37
8.4.3 Handler box . 38
8.4.4 Media information box . 39
8.4.5 Media information header boxes . 39
8.4.6 Extended language tag . 40
8.5 Sample tables . 40
8.5.1 Sample table box . 40
8.5.2 Sample description box .41
8.5.3 Degradation priority box .43
8.5.4 Sample scale box .43
8.6 Track time structures .43
8.6.1 Time to sample boxes .43
8.6.2 Sync sample box . 49
8.6.3 Shadow sync . 50
8.6.4 Independent and disposable samples box .52
8.6.5 Edit box . 53
8.6.6 Edit list box . 54
8.7 Track data layout structures . 56
8.7.1 Data information box. 56
8.7.2 Data reference box .57
8.7.3 Sample size boxes .59
8.7.4 Sample to chunk box . 60
8.7.5 Chunk offset box .61
8.7.6 Padding bits box .62
8.7.7 Sub-sample information box .62
8.7.8 Sample auxiliary information sizes box . 65
8.7.9 Sample auxiliary information offsets box.67
8.7.10 Sub-sample Reference Table Box. 68
8.8 Movie fragments . 69
8.8.1 Movie extends box . 69
8.8.2 Movie extends header box .70
8.8.3 Track extends box .71
8.8.4 Movie fragment box . 72
8.8.5 Movie fragment header box . 72
8.8.6 Track fragment box . 73
8.8.7 Track fragment header box . 73
8.8.8 Track fragment run box . . 75
8.8.9 Movie fragment random access box .76
8.8.10 Track fragment random access box . 77
8.8.11 Movie fragment random access offset box . 78
8.8.12 Track fragment decode time box . 79
8.8.13 Level assignment box . 80
8.8.14 Sample auxiliary information in movie fragments. 81
8.8.15 Track extension properties box . 82
8.8.16 Alternative startup sequence properties box . 82
8.8.17 Metadata and user data in movie fragments . 83
8.8.18 Redundant Sample Original Timing . 83
8.9 Sample group structures . 85
8.9.1 Overview . 85
8.9.2 Sample to group box . 85
8.9.3 Sample group description box . 87
8.9.4 Representation of group structures in movie fragments . 89
8.9.5 Compact sample to group box . 90
8.10 User data . 92

© ISO/IEC 2026 – All rights reserved
iv
8.10.1 User data box . 92
8.10.2 Copyright box . 93
8.10.3 Track selection box . 93
8.10.4 Track kind . 95
8.10.5 Label box . 95
8.11 Metadata support . 96
8.11.1 MetaBox . 96
8.11.2 XML boxes . . 98
8.11.3 Item location box . 98
8.11.4 Primary item box . 102
8.11.5 Item protection box . 102
8.11.6 Item information box . 103
8.11.7 Additional metadata container box . 105
8.11.8 Metabox Relation box . 105
8.11.9 URL forms for MetaBoxes . . 105
8.11.10 Static metadata . 106
8.11.11 Item data box . 107
8.11.12 Item reference box . 107
8.11.13 Auxiliary video metadata . 108
8.11.14 Item properties box . 108
8.11.15 Brand item property .110
8.11.16 Handler property .110
8.11.17 T.35 item . 111
8.12 File delivery format support . 111
8.12.1 Overview . 111
8.12.2 FD item information box . 112
8.12.3 File partition box . 113
8.12.4 FEC reservoir box .114
8.12.5 FD session group box . 115
8.12.6 Group ID to name box . . .116
8.12.7 File reservoir box .116
8.13 Sub tracks .117
8.13.1 Overview .117
8.13.2 Backward compatibility .117
8.13.3 Sub track box. 118
8.13.4 Sub track information box . 118
8.13.5 Sub track definition box .119
8.13.6 Sub track sample group box . 120
8.14 Segments . 120
8.14.1 Overview . 120
8.14.2 Segment type box . 120
8.14.3 Segment index box . 121
8.14.4 Subsegment index box . 124
8.14.5 Producer reference time box . 126
8.15 Entity grouping . 127
8.15.1 General . 127
8.15.2 Groups list box . 128
8.15.3 Entity to group box.128
8.15.4 Entity group definitions .129
8.16 Compressed boxes . 131
8.16.1 Overview and processing . 131
8.16.2 Processing model . 131
8.16.3 General syntax. 133
8.16.4 General semantics . 133
8.16.5 Original file-type box . 133
8.16.6 Compressed movie box .134
8.16.7 Compressed movie fragment box .134
8.16.8 Compressed segment index box .134
8.16.9 Compressed subsegment index box . 135

© ISO/IEC 2026 – All rights reserved
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9 Hint track formats .135
9.1 RTP and SRTP hint track format . 135
9.1.1 Overview . 135
9.1.2 Sample entry format . 136
9.1.3 Sample format .138
9.1.4 SDP information . 140
9.1.5 Statistical information .141
9.2 ALC/LCT and FLUTE hint track format .141
9.2.1 Overview .141
9.2.2 Design principles .142
9.2.3 Sample entry format .143
9.2.4 Sample format . 144
9.3 MPEG-2 transport hint track format .147
9.3.1 Overview .147
9.3.2 Design principles .147
9.3.3 Sample entry format . 149
9.3.4 Sample format . 151
9.3.5 Protected MPEG 2 transport stream hint track . 153
9.4 RTP, RTCP, SRTP and SRTCP reception hint tracks . 153
9.4.1 RTP reception hint track . 153
9.4.2 RTCP reception hint track . 156
9.4.3 SRTP reception hint track . 158
9.4.4 SRTCP reception hint tracks . 159
9.4.5 Protected RTP reception hint track . 160
9.4.6 Recording procedure . 160
9.4.7 Parsing procedure . .161
10 Sample groups .161
10.1 Random access recovery points .161
10.1.1 Definition .161
10.1.2 Syntax .161
10.1.3 Semantics .161
10.2 Rate share groups . 162
10.2.1 Overview . 162
10.2.2 Rate share sample group description entry . 163
10.2.3 Relationship between tracks . 164
10.2.4 Bitrate allocation. 164
10.3 Alternative startup sequences . 165
10.3.1 Definition . 165
10.3.2 Syntax . . 165
10.3.3 Semantics . 166
10.3.4 Examples . 166
10.4 Random access point (RAP) sample group . 168
10.4.1 Definition . 168
10.4.2 Syntax . . 169
10.4.3 Semantics . 169
10.5 Temporal level sample group . 169
10.5.1 Definition . 169
10.5.2 Syntax . 169
10.5.3 Semantics . 169
10.6 Stream access point sample group . 169
10.6.1 Definition . 169
10.6.2 Syntax .170
10.6.3 Semantics .
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