ISO/IEC 14496-32:2021

INTERNATIONAL ISO/IEC
STANDARD 14496-32
First edition
2021-01
Information technology — Coding of
audio-visual objects —
Part 32:
File format reference software and
conformance
Reference number
©
ISO/IEC 2021
© ISO/IEC 2021
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Reference software . 2
5 Conformance . 2
5.1 Overview . 2
5.2 Standard specific considerations . 2
5.2.1 Considerations for ISO/IEC 14496-12, 14496-14 and 14496-15 . 2
5.2.2 Considerations for ISO/IEC 14496-30 . 2
5.2.3 Considerations for ISO/IEC 23008-12 . 3
5.3 File documentation . 3
5.3.1 Files from related conformance programs . 3
5.3.2 Files unique to this conformance program . 4
Annex A (informative) Other tools .21
Bibliography .22
© ISO/IEC 2021 – All rights reserved iii

Foreword
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Commission) form the specialized system for worldwide standardization. National bodies that
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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).
Attention is drawn to the possibility that some of the elements of this document may be the subject
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iso/ foreword .html.
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.
A list of all parts in the ISO/IEC 14496 series can be found on the ISO website.
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.
iv © ISO/IEC 2021 – All rights reserved

INTERNATIONAL STANDARD ISO/IEC 14496-32:2021(E)
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 MPEG-4 and MPEG-H. Since these documents share a lot of technology, their reference software
and conformance program are being handled together. These documents 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 in order 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 terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
© ISO/IEC 2021 – All rights reserved 1

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 provided at:
https:// standards .iso .org/ iso -iec/ 14496/ -32/ ed -1/ en/ reference _software/
Additional tools exercising features of the ISO base media file format (ISOBMFF) are described in
Annex A.
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:
https:// standards .iso .org/ iso -iec/ 14496/ -32/ ed -1/ 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 (see Annex A). 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 may have validation tools
tailored to their areas.
An HTML report (conformance_report.html) indicates which code points (e.g. box codes and track
reference types) defined in these documents are used in which conformance file.
5.2 Standard specific considerations
5.2.1 Considerations for ISO/IEC 14496-12, 14496-14 and 14496-15
For ISOBMFF conformance, an associated file (ff-conformance.xls) is used to list the features in groups,
and to document which files exercise each feature. Features not currently covered by any file are
marked with the sign “---“.
The file ff-conformance.xls has two spreadsheets. The first briefly lists the areas and features covered,
and then has a column for each proposed file. The second sheet provides a brief description of each area
and feature, by line.
5.2.2 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.
2 © ISO/IEC 2021 – All rights reserved

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.
5.2.3 Considerations for ISO/IEC 23008-12
For HEIF conformance, an associated file (HEIF_conformance.xlsx) is used to describe the current files,
associated input bitstreams, and a specification coverage analysis of the conformance.
The spreadsheet "HEIF_conformance.xlsx" contains information of the tested features and their
mapping to the provided conformance files. It was created by picking all normative statements (shall,
shall not, etc.) in the HEIF specification. These are collected in the "Areas tested" column of the sheet.
The column "Description" presents a brief description of the tested feature, exercising the associated
normative statement in the specification.
The column "File ID" provides the file name.
The column "brands" indicates the HEIF brands that are included in FileTypeBox of the respective file
(in the "Test Content" sheet) or concern the respective test case (in the "Test Cases" sheet. The aim of
the column is to help implementers to pick files that concern the brand of their interest. For example,
implementers of the 'heic' brand should only consider the files with that brand included.
Note that the spreadsheet enables filtering by content, e.g. by selecting only a particular File ID (at cell
A1), one can see which features are exercised by a particular file.
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".
© ISO/IEC 2021 – All rights reserved 3

The following files are also included for ISOBMFF conformance:
— ./mpeg-audio-conformance/ac01.mp4 (padb)
— ./mpeg-audio-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:
— ./uvvu/Solekai002_1280_23_1x1_v7clear.uvvu
— ./uvvu/Solekai007_1920_29_1x1_v7clear.uvvu
Original files can be obtained from http:// uvvuwiki .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:
— ./gr
...