ISO/IEC 23090-24:2025

Information technology — Coded representation of immersive media — Part 24: Conformance and reference software for scene description

This document specifies the conformance and reference software for ISO/IEC 23090-14.

Technologies de l'information — Représentation codée de média immersifs — Partie 24: Conformité et logiciel de référence pour la description de scènes

General Information

• Status: Published
• Publication Date: 19-May-2025
• 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 - Coding of audio, picture, multimedia and hypermedia information
• Current Stage: 6060 - International Standard published
• Start Date: 20-May-2025
• Due Date: 17-Jul-2024
• Completion Date: 20-May-2025

Overview

ISO/IEC 23090-24:2025 is an international standard developed by ISO and IEC, focusing on the coded representation of immersive media. Specifically, this part of the standard provides the conformance and reference software for scene description, as defined in ISO/IEC 23090-14. By establishing an interoperable framework, it ensures reliable testing, validation, and implementation of immersive media scene descriptions, supporting advancements in virtual reality (VR), augmented reality (AR), and mixed reality (MR) experiences.

This standard is integral to the MPEG-I suite, enabling industry stakeholders to verify compliance and integrate new features in multimedia and immersive content applications. With a strong focus on scene description interoperability, the reference software and conformance tools defined in ISO/IEC 23090-24:2025 facilitate robust multimedia workflow development.

Key Topics

• Reference Software for Scene Description
  The standard provides a standalone Python module called pympegsd, offering a reference implementation for MPEG-I scene description extensions, as specified in ISO/IEC 23090-14. This module supports several extensions for timed media, video textures, spatial audio, mesh linking, and more.

• Conformance Testing Tools
  ISO/IEC 23090-24 includes software tools for validating scene descriptions against the ISO/IEC 23090-14 specification. These tools verify JSON schema conformance, binary buffer accuracy, metadata carriage, and audio/image stream integrity based on defined MPEG extensions.

• Extension Support
  Key MPEG-specific extensions handled include:

  • MPEG_media: referencing external media
  • MPEG_texture_video: video textures
  • MPEG_audio_spatial: spatial audio integration
  • MPEG_buffer_circular: circular buffers for timed media
  • MPEG_mesh_linking: mesh mapping and linking
  • Haptics and AR scene playback support

• Software Integration and Dependencies
  The reference software is designed with modular dependencies, leveraging Python libraries such as trimesh, pyglet, and networkx, as well as interfacing with spatial audio renderers and the OpenXR framework for immersive rendering.

• Validator and Carriage Libraries
  Tools like the MPEG glTF-validator and libSDCarriage ensure that both the scene description syntax and binary data comply with the required standards.

Applications

ISO/IEC 23090-24:2025 supports practical use cases in a broad range of immersive media and information technology domains, including:

• Interactive and Immersive Media Experiences
  Enables production and validation of VR, AR, and MR applications by ensuring scene descriptions are standardized and interoperable.

• 3D Asset Pipelines
  Integrates with glTF 2.0 (ISO/IEC 12113), supporting efficient runtime delivery and validation of 3D assets in multimedia systems.

• Media System Development
  Facilitates test scenario creation and new feature prototyping for developers working with scene description in immersive environments.

• Validation and Testing Environments
  Used to automatically validate files and bitstreams-such as MPEG Immersive Video (MIV)-to guarantee fidelity with industry standards and expected rendering processes.

• Research and Standards Conformance
  Offers a reference implementation for academic, research, or vendor-oriented evaluation of new features and conformance tests.

Related Standards

Organizations and professionals implementing ISO/IEC 23090-24:2025 may also reference:

• ISO/IEC 23090-14: Defines the underlying scene description framework and extension mechanisms.
• ISO/IEC 12113: Specifies the Khronos glTF 2.0 format for runtime 3D asset delivery.
• ISO/IEC 21778: Sets out the JSON data interchange syntax used in scene description extensions.
• glTF-Validator: Open-source tool from the Khronos Group for glTF 2.0 validation.
• OpenXR: Cross-platform XR framework for immersive device compatibility.
• MPEG Immersive Video (MIV): Standards for immersive video content delivery and playback.

Visit the ISO official website for further details and access to the complete standards catalogue.

Keywords: immersive media, scene description, MPEG-I, ISO/IEC 23090-24:2025, conformance software, reference software, glTF, virtual reality, augmented reality, multimedia standards, MPEG extensions, spatial audio, haptics, reference implementation

Standards Content (Sample)

International
Standard
ISO/IEC 23090-24
First edition
Information technology — Coded
2025-05
representation of immersive media —
Part 24:
Conformance and reference
software for scene description
Technologies de l'information — Représentation codée de média
immersifs —
Partie 24: Conformité et logiciel de référence pour la description
de scènes
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
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 2025 – All rights reserved
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Reference software for ISO/IEC-23090-14 MPEG-I scene description . 1
4.1 General .1
4.2 Description .2
4.3 Dependencies .3
4.3.1 Spatial audio .3
4.3.2 OpenXR .3
4.4 Usage .4
4.4.1 Installation .4
4.5 Support for MIV content .4
4.5.1 Build instructions .5
4.5.2 Run instructions .5
4.5.3 Location .6
4.6 Support for the Haptics extension . .6
4.7 Support for AR scene playback .6
4.8 Issues .6
4.9 License .7
5 ISO/IEC-23090-14 MPEG-I scene description conformance . 7
5.1 Overview .7
5.2 glTF and MPEG extension schema validation .8
5.2.1 General .8
5.2.2 JSON schema validation .8
5.2.3 Binary buffer validation .8
5.2.4 Source image validation.8
5.2.5 Audio validation .9
5.3 Scene description metadata sample conformance .9
6 Conformance software for ISO/IEC 23090-14 MPEG-I scene description . 9
6.1 Overview .9
6.2 glTF-validator .9
6.2.1 Overview .9
6.2.2 Software repository .10
6.3 Carriage library .10
6.3.1 Overview .10
6.3.2 Software repository .11
7 Test vectors . .11
7.1 Overview .11
7.2 MIV bitstream .11
Bibliography .13

© 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.
A list of all parts in the ISO/IEC 23090 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
Introduction
The conformance and reference software of ISO/IEC 23090-14 serves following main purposes:
— Validation of the written specification of the parts of ISO/IEC 23090-14;
— Clarification of the written specification of the parts of ISO/IEC 23090-14;
— Conformance testing for checking interoperability for the various applications against the reference
software which aims to be compliant with ISO/IEC 23090-14.

© ISO/IEC 2025 – All rights reserved
v
International Standard ISO/IEC 23090-24:2025(en)
Information technology — Coded representation of
immersive media —
Part 24:
Conformance and reference software for scene description
1 Scope
This document specifies the conformance and reference software for ISO/IEC 23090-14.
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 23090-14:2023, Information technology — Coded representation of immersive media — Part 14: Scene
description
ISO/IEC 12113, Information technology — Runtime 3D asset delivery format — Khronos glTF™ 2.0
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 23090-14 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/
3.1
glTF file
file conforming to ISO/IEC 12113
4 Reference software for ISO/IEC-23090-14 MPEG-I scene description
4.1 General
The reference software is available at: https:// standards .iso .org/ iso -iec/ 23090/ -24/ ed -1/ en/ .
An architectural diagram for the reference software is shown in Figure 1.

© ISO/IEC 2025 – All rights reserved
Figure 1 — Architectural diagram of the pympegsd package
4.2 Description
The MPEG scene description reference software is a standalone Python module called pympegsd. The
module contains the reference implementation for MPEG-I scene description extensions as specified in
ISO/IEC 23090-14. The implementation in pympegsd supports features which are defined as extensions to
ISO/IEC 12113 under the MPEG namespace as shown in Table 1, for details see MPEG-defined extensions in
ISO/IEC 23090-14. The pympegsd software package is implemented using Python language.
NOTE The support for carriage formats as specified in Clause 7 of ISO/IEC 23090-14:2023 is in progress.
The pympegsd package has external dependencies on other software packages such as trimesh and others.
pympegsd supports timed data. The pympegsd interacts with trimesh and pympegsd which are responsible for
expected rendering process of the timed data after it is decoded via operation supported through pipelines.
Table 1 — ISO/IEC 12113 extensions in ISO/IEC 23090-14
Extension name Brief description Implementation status
MPEG_media Extension for referencing external Yes
media sources.
MPEG_accessor_timed An accessor extension to support Yes
timed media.
MPEG_buffer_circular A buffer extension to support Yes
circular buffers.
MPEG_scene_dynamic An extension to support scene No
updates.
MPEG_texture_video A texture extension to support Yes
video textures.
MPEG_mesh_linking An extension to link two meshes Yes
and provide mapping information

© ISO/IEC 2025 – All rights reserved
TTabablele 1 1 ((ccoonnttiinnueuedd))
Extension name Brief description Implementation status
MPEG_audio_spatial Adds support for spatial audio. Yes
MPEG_viewport_recommended An extension to describe a rec- Yes
ommended viewport.
MPEG_animation_timing An extension to control animation No
timelines.
A new feature proposal to the ISO/IEC 23090-14 specification requires providing a test scenario as well as
an implementation which demonstrates proper rendering of the test scenario scene. The implementations
should be provided as a new branch with a merge request to reference software for ISO/IEC 23090-14.
4.3 Dependencies
The list of library packages in Table 2 are dependencies for pympegsd.
Table 2 — Library packages
Library pack- Description Version
age
av Python binding to FFmpeg library 9.2.0
networkx Creating and manipulating graphs and network 2.5
pillow Imaging processing library 8.0.1
pyglet Windowing and multimedia library 1.5.8
scipy Fast N-dimensional array manipulation 1.5.3
bitstream Manage binary data as bitstreams 2.6.0
trimesh Loading and using triangular meshes 3.5.6
pyopenxr Python binding for OpenXR SDK 1.0.2301
pyrender Rendering engine 0.1.45
aiortc Library for real-time communication 1.3.2
aiohttp Asynchronous HTTP client/server 3.8.1
4.3.1 Spatial audio
1)
To run test vectors for spatial demos, a spatial audio renderer library such as Soloud audio library may be used.
4.3.2 OpenXR
2)
pyopenxr is a Python module which provides a Python binding to Khronos OpenXR™ SDK. The OpenXR
backend allows for rendering a scene to any OpenXR compatible device. The dependencies for running the
renderer need to be installed first.
On Windows platforms, any compatible device that is registered as the default OpenXR device may be used
to render the scene.
1) Soloud audio library is available at: https:// sol .gfxile .net/ soloud/
...