ISO/IEC 14496-32:2025

International
Standard
ISO/IEC 14496-32
Second edition
Information technology — Coding of
2025-04
audio-visual objects —
Part 32:
File format reference software and
conformance
Reference number
© ISO/IEC 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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© ISO/IEC 2025 – All rights reserved
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Reference software . 1
5 Conformance . 2
5.1 Overview .2
5.2 Standard specific considerations .2
5.2.1 Considerations for ISO/IEC 14496-30 .2
5.3 File documentation .3
5.3.1 Files from related conformance programs .3
5.3.2 Files unique to this conformance program .4
Bibliography .23

© ISO/IEC 2025 – All rights reserved
iii
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 Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.
This second edition cancels and replaces the first edition (ISO/IEC 14496-32:2021), which has been
technically revised.
The main changes are as follows:
— new conformance files have been added to the conformance suite with additional documentation in
Clause 5;
— obsolete spreadsheets and html files have been removed.
A list of all parts in the ISO/IEC 14496 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 2025 – All rights reserved
iv
International Standard ISO/IEC 14496-32:2025(en)
Information technology — Coding of audio-visual objects —
Part 32:
File format reference software and conformance
1 Scope
This document describes the reference software and conformance suite for the file format documents
in multiple standards. Since these standards share a lot of technology, their reference software and
conformance program are being handled together. These standards are: ISO/IEC 14496-12, ISO/IEC 14496-14,
ISO/IEC 14496-15, ISO/IEC 14496-30 and ISO/IEC 23008-12.
The purpose of the conformance suite is to cover the set of valid features that can be exercised in the file
format. Media conformance is not covered, though of course to exercise the file format features, media will
be stored.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 14496-12, Information technology — Coding of audio-visual objects — Part 12: ISO base media file format
ISO/IEC 14496-14, Information technology — Coding of audio-visual objects — Part 14: MP4 file format
ISO/IEC 14496-15, Information technology — Coding of audio-visual objects — Part 15: Carriage of network
abstraction layer (NAL) unit structured video in the ISO base media file format
ISO/IEC 14496-30, Information technology — Coding of audio-visual objects — Part 30: Timed text and other
visual overlays in ISO base media file format
ISO/IEC 23008-12, Information technology — High efficiency coding and media delivery in heterogeneous
environments — Part 12: Image File Format
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 14496-12, ISO/IEC 14496-14,
ISO/IEC 14496-15, ISO/IEC 14496-30 and ISO/IEC 23008-12 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Reference software
The reference software for ISO/IEC 14496-12, ISO/IEC 14496-14, ISO/IEC 14496-15, ISO/IEC 14496-30, and
ISO/IEC 23008-12 is available at: http:// standards .iso .org/ iso -iec/ 14496/ -32/ ed -2/ en/ reference _software/

© ISO/IEC 2025 – All rights reserved
This link contains version v.0.3.0 of the software with the changelog included in the software package, which
documents new features compared to older versions.
5 Conformance
5.1 Overview
The conformance suite for ISO/IEC 14496-12, ISO/IEC 14496-14, ISO/IEC 14496-15, ISO/IEC 14496-30 and
ISO/IEC 23008-12 is provided at: http:// standards .iso .org/ iso -iec/ 14496/ -32/ ed -2/ en/ conformance/
The suite of conformance tests does not currently cover deliberately errored files. However, such files do
occur in practice and implementations should be written to be resilient.
There is no official reference tool provided to check the conformance of files. However, such tools do exist.
The reference software can be used to open files in ‘debug’ mode and provide a listing of what it finds, and
other trade associations and standards bodies might have validation tools tailored to their areas.
5.2 Standard specific considerations
5.2.1 Considerations for ISO/IEC 14496-30
Two files are proposed regarding:
— WebVTT;
— TTML.
There are several general features of ISO/IEC 14496-30 which are not exercised in the above files, specifically:
— a track with 'mul' language;
— a track sharing resources (images, …) between samples through the use of a MetaBox;
— file with a subtitle and a font track.
There are several features specific to the carriage of TTML in MP4 which are not exercised:
— timing:
— ‘empty’ sample;
— sample with a document containing a larger time range than the sample presentation range;
— sample with a document whose time range is smaller than the sample range;
— sample entry format:
— with multiple namespace values;
— with schema location;
— with auxiliary mime types;
— sample format:
— with additional resources.
© ISO/IEC 2025 – All rights reserved
5.3 File documentation
5.3.1 Files from related conformance programs
5.3.1.1 Overview
Some files provided in this suite originate from external conformance programs, from other ISO documents
or external specifications. The latest version should be obtained from their original source as indicated in
the following sections.
5.3.1.2 Audio-based conformance files
ISO/IEC 14496-26 provides several MP4 files containing MPEG-4 AAC, MPEG-D MPS, and MPEG-D USAC
streams and exercising features of the ISOBMFF. Within these files, only some are necessary to cover all the
ISOBMFF features. These files are from the “AAC-Conformance” part. The features specifically exercised by
these files compared to existing files are: 'padb' and 'm4ae'.
The following files are also included for ISOBMFF conformance:
— ./mpeg-audio-conformance/aac-conformance/ac01.mp4 ('padb')
— ./mpeg-audio-conformance/aac-conformance/sls2100_aot02_048_16.mp4 ('m4ae')
Original files can be obtained from ISO/IEC 14496-26.
5.3.1.3 Timed text conformance files
DECE produced a set of Timed Text test vector files with video and audio tracks. Some of these files exercise
features of ISO/IEC 14496-12 and ISO/IEC 14496-30. The following files are added as part of ISOBMFF
conformance:
— Solekai002_1280_23_1x1_v7clear.uvu
— Solekai007_1920_29_1x1_v7clear.uvu
Original files can be obtained from https:// www .uvcentral .com/ cff/ cff -test -files .html.
5.3.1.4 DASH-based conformance files
The ISO/IEC 23009 series specifies the use of ISOBMFF files for adaptive streaming. ISO/IEC 23009-2
contains the following files that exercise specific features of the ISOBMFF:
— ./green/video_2500000bps_0.mp4
— ./green/meta_2500000bps_0.mp4m
— ./nalu/svc/mp4-onDemand-LastTime-depRep.mp4
— ./nalu/mvc/DDF_10s_25fps.mp4
Original files can be obtained from https:// testassets .dashif .org/ .
5.3.1.5 MAF-based conformance files
The ISO/IEC 23000 series uses the ISOBMFF standard at its core and contains some files (related to the PAAF
and VSAF standards). None of these files exercise new features, but they exercise some features differently.
The following files are copied in this ISOBMFF conformance:
— ./maf/vsaf/1.mp4
— ./maf/paaf/01_output_a.paf
© ISO/IEC 2025 – All rights reserved
Original files can be obtained from ISO/IEC 23000-6 and ISO/IEC 23000-10.
5.3.2 Files unique to this conformance program
5.3.2.1 a1-foreman-QCIF.mp4
This file is very simple. It has an MPEG-4 video part 2 visual track, and an AAC track, interleaved; and a
minimal BIFS scene and OD track, with an IOD.
5.3.2.2 a2-foreman-QCIF-hinted.mp4
This file is basically the same as a1-foreman-QCIF.mp4 but hinted for RTP transmission.
5.3.2.3 a3-tone-protected.mp4
This file uses the protected stream structures. The keys are also supplied (a3c-prot-keys.txt), and the result
of de-protection (a3b-tone-deprot.mp4, for comparison).
5.3.2.4 a4-tone-fragmented.mp4
This file uses movie fragments. The initial 1-second movie is followed by a 1-second movie fragment.
Fragment-aware readers should play 2 second of content, fragment-unaware readers only 1 second.
5.3.2.5 a5-foreman-AVC.mp4
This is a very simple video-only main profile AVC file. Since it is main profile, composition offsets are used.
5.3.2.6 a6_tone_multifile.mp4
This is the same to
...