ISO/IEC FDIS 23008-3

Information technology — High efficiency coding and media delivery in heterogeneous environments — Part 3: 3D audio

This document specifies technology that supports the efficient transmission of immersive audio signals and flexible rendering for the playback of immersive audio in a wide variety of listening scenarios. These include home theatre setups with 3D loudspeaker configurations, 22.2 loudspeaker systems, automotive entertainment systems and playback over headphones connected to a tablet or smartphone.

Technologies de l'information — Codage à haute efficacité et livraison des medias dans des environnements hétérogènes — Partie 3: Audio 3D

General Information

• Status: Not Published
• 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 6 - MPEG Audio coding
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 03-Nov-2025
• Completion Date: 03-Nov-2025

Relations

• Revises: ISO/IEC 23008-3:2022 - Information technology — High efficiency coding and media delivery in heterogeneous environments — Part 3: 3D audio
• Effective Date: 17-Aug-2024

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/IEC
FDIS
23008-3
ISO/IEC JTC 1/SC 29
Information technology — High
Secretariat: JISC
efficiency coding and media
Voting begins on:
delivery in heterogeneous
2025-11-03
environments —
Voting terminates on:
2025-12-29
Part 3:
3D audio
Technologies de l'information — Codage à haute efficacité et
livraison des medias dans des environnements hétérogènes —
Partie 3: Audio 3D
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/IEC FDIS 23008­3:2025(en) © ISO/IEC 2025

FINAL DRAFT
International
Standard
ISO/IEC
FDIS
23008-3
ISO/IEC JTC 1/SC 29
Information technology — High
Secretariat: JISC
efficiency coding and media
Voting begins on:
delivery in heterogeneous
environments —
Voting terminates on:
Part 3:
3D audio
Technologies de l'information — Codage à haute efficacité et
livraison des medias dans des environnements hétérogènes —
Partie 3: Audio 3D
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO/IEC 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/IEC FDIS 23008­3:2025(en) © ISO/IEC 2025

© ISO/IEC 2025 – All rights reserved
ii
ISO/IEC 23008-3:2025(en)
Contents Page
Foreword . xii
Introduction . xii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols, abbreviated terms and conventions . 1
3.1 Terms and definitions . 1
3.2 Symbols, abbreviated terms and conventions . 2
3.2.1 Symbols and abbreviated terms . 2
3.2.2 Conventions . 2
4 Technical overview . 2
4.1 Decoder block diagram . 2
4.2 Overview over the codec building blocks . 3
4.3 Efficient combination of decoder processing blocks in the time domain and QMF
domain . 6
4.4 Rule set for determining processing domains . 9
4.4.1 Audio core codec processing domain . 9
4.4.2 Mixing . 10
4.4.3 DRC-1 Operation domains (DRC in rendering context) . 10
4.4.4 Audio core codec interface domain to rendering . 10
4.4.5 Rendering context . 10
4.4.6 Post-processing context . 11
4.4.7 End-of-chain context . 11
4.5 Sample rate converter . 11
4.6 Decoder delay . 11
4.7 Contribution mode of MPEG-H 3D audio . 12
4.8 MPEG-H 3D audio profiles and levels . 12
4.8.1 General . 12
4.8.2 Profiles . 13
5 MPEG-H 3D audio core decoder . 27
5.1 Definitions . 27
5.1.1 Joint stereo . 27
5.1.2 MPEG surround based stereo (MPS 212) . 28
5.2 Syntax . 28
5.2.1 General . 28
5.2.2 Decoder configuration . 28
5.2.3 MPEG-H 3D audio core bitstream payloads . 51
5.3 Data structure . 72
5.3.1 General . 72
5.3.2 General configuration data elements . 72
5.3.3 Loudspeaker configuration data elements . 75
5.3.4 Core decoder configuration data elements . 77
5.3.5 Downmix matrix data elements . 81
5.3.6 HOA rendering matrix data elements . 84
5.3.7 Signal group information elements . 87
5.3.8 Low frequency enhancement (LFE) channel element, mpegh3daLfeElement() . 87
5.3.9 Compatible profile and levels sets. 88
5.4 Configuration element descriptions . 88
5.4.1 General . 88
5.4.2 Downmix configuration . 88
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 23008-3:2025(en)
5.4.3 HOA rendering matrix configuration . 94
5.5 Tool descriptions . 98
5.5.1 General . 98
5.5.2 Quad channel element. 98
5.5.3 Transform splitting . 100
5.5.4 MPEG surround for mono to stereo upmixing . 107
5.5.5 Enhanced noise filling . 110
5.5.6 Audio pre-roll . 134
5.5.7 Fullband LPD . 137
5.5.8 Time-domain bandwidth extension . 148
5.5.9 LPD stereo coding . 161
5.5.10 Multichannel coding tool . 169
5.5.11 Filterbank and block switching . 179
5.5.12 Frequency domain prediction . 180
5.5.13 Long-term postfilter . 183
5.5.14 Tonal component coding . 188
5.5.15 Internal channel on MPS212 for low complexity format conversion . 198
5.5.16 High resolution envelope processing (HREP) tool. 210
5.6 Buffer requirements . 216
5.6.1 Minimum decoder input buffer . 216
5.6.2 Bit reservoir . 216
5.6.3 Maximum bit rate . 217
5.7 Stream access point requirements and inter-frame dependency . 217
6 Dynamic range control and loudness processing . 218
6.1 General . 218
6.2 Description . 218
6.3 Syntax . 219
6.3.1 Loudness metadata . 219
6.3.2 Dynamic range control metadata . 219
6.3.3 Data elements . 220
6.4 Decoding process . 222
6.4.1 General . 222
6.4.2 Dynamic range control . 224
6.4.3 Usage of downmixId in MPEG-H . 224
6.4.4 DRC set selection process . 225
6.4.5 DRC-1 for SAOC 3D Content . 227
6.4.6 DRC-1 for HOA content . 228
6.4.7 Loudness normalization . 229
6.4.8 Peak limiter . 229
6.4.9 Time-synchronization of DRC gains . 230
6.4.10 Default parameters . 230
7 Object metadata decoding . 230
7.1 General . 230
7.2 Description . 230
7.3 Syntax . 231
7.3.1 Object metadata configuration . 231
7.3.2 Top level object metadata syntax . 232
7.3.3 Subsidiary payloads for efficient object metadata decoding . 233
7.3.4 Subsidiary payloads for object metadata decoding with low delay . 238
7.3.5 Enhanced object metadata configuration . 244
7.4 Data structure . 247
7.4.1 Definition of ObjectMetadataConfig() payloads . 247
7.4.2 Efficient object metadata decoding . 247
7.4.3 Object metadata decoding with low delay . 255
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 23008-3:2025(en)
7.4.4 Enhanced object metadata . 260
8 Object rendering . 263
8.1 Description . 263
8.2 Terms and definitions . 263
8.3 Input data . 264
8.4 Processing . 265
8.4.1 General remark . 265
8.4.2 Imaginary loudspeakers . 265
8.4.3 Dividing the loudspeaker setup into a triangle mesh . 266
8.4.4 Rendering algorithm . 268
9 SAOC 3D . 272
9.1 Description . 272
9.2 Definitions . 272
9.3 Delay and synchronization . 274
9.4 Syntax . 274
9.4.1 Payloads for SAOC 3D . 274
9.4.2 Definition of SAOC 3D payloads . 278
9.5 SAOC 3D processing . 280
9.5.1 Compressed data stream decoding and dequantization of SAOC 3D data . 280
9.5.2 Time/frequency transforms . 280
9.5.3 Signals and parameters . 281
9.5.4 SAOC 3D decoding . 283
9.5.5 Dual mode . 288
10 Generic loudspeaker rendering/format conversion . 288
10.1 Description . 288
10.2 Definitions . 290
10.2.1 General remarks . 290
10.2.2 Variable definitions . 290
10.3 Processing . 290
10.3.1 Application of transmitted downmix matrices . 290
10.3.2 Application of transmitted equalizer settings . 295
10.3.3 Downmix processing involving multiple channel groups . 295
10.3.4 Initialization of the format converter . 296
10.3.5 Audio signal processing . 312
11 Immersive loudspeaker rendering/format conversion . 318
11.1 Description . 318
11.2 Syntax . 320
11.3 Definitions . 320
11.3.1 General remarks . 320
11.3.2 Variable definitions . 321
11.4 Processing . 322
11.4.1 Initialization of the format converter . 322
11.4.2 Audio signal processing . 364
12 Higher order ambisonics (HOA) . 372
12.1 Technical overview . 372
12.1.1 Block diagram . 372
12.1.2 Overview of the decoder tools . 373
12.2 Syntax . 374
12.2.1 Configuration of HOA elements . 374
12.2.2 Payloads of HOA elements . 378
12.3 Data structure . 391
12.3.1 Definitions of HOA Config . 391
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 23008-3:2025(en)
12.3.2 Syntax of getSubbandBandwidths() . 395
12.3.3 Definitions of HOA payload . 396
12.4 HOA tool description . 403
12.4.1 HOA frame converter . 403
12.4.2 Spatial HOA decoding . 419
12.4.3 HOA renderer . 448
12.4.4 Layered coding for HOA . 457
13 Binaural renderer . 460
13.1 General . 460
13.2 Frequency-domain binaural renderer . 460
13.2.1 General . 460
13.2.2 Definitions . 462
13.2.3 Parameterization of binaural room impulse responses . 466
13.2.4 Frequency-domain binaural processing . 478
13.3 Time-domain binaural renderer . 485
13.3.1 General . 485
13.3.2 Definitions . 486
13.3.3 Parameterization of binaural room impulse responses . 488
13.3.4 Time-domain binaural processing . 492
14 MPEG-H 3D audio stream (MHAS) . 493
14.1 Overview . 493
14.2 Syntax . 494
14.2.1 Main MHAS syntax elements . 494
14.2.2 Subsidiary MHAS syntax elements . 496
14.3 Semantics . 496
14.3.1 mpeghAudioStreamPacket() . 496
14.3.2 MHASPacketPayload() . 497
14.3.3 Subsidiary MHAS packets . 499
14.4 Description of MHASPacketTypes . 499
14.4.1 PACTYP_FILLDATA . 499
14.4.2 PACTYP_MPEGH3DACFG . 499
14.4.3 PACTYP_MPEGH3DAFRAME . 499
14.4.4 PACTYP_SYNC . 500
14.4.5 PACTYP_SYNCGAP . 500
14.4.6 PACTYP_MARKER . 500
14.4.7 PACTYP_CRC16 and PACTYP_CRC32 . 501
14.4.8 PACTYP_DESCRIPTOR . 501
14.4.9 PACTYP_USERINTERACTION . 501
14.4.10 PACTYP_LOUDNESS_DRC . 501
14.4.11 PACTYP_BUFFERINFO . 502
14.4.12 PACTYP_GLOBAL_CRC16 and PACTYP_ GLOBAL_CRC32 . 502
14.4.13 PACTYP_AUDIOTRUNCATION . 502
14.4.14 PACTYP_AUDIOSCENEINFO . 503
14.4.15 PACTYP_EARCON . 503
14.4.16 PACTYP_PCMCONFIG . 504
14.4.17 PACTYP_PCMDATA . 504
14.4.18 PACTYP_LOUDNESS . 504
14.4.19 MHASPacketType specific requirements for MHASPacketLabel . 504
14.5 Application examples . 505
14.5.1 Light-weighted broadcast . 505
14.5.2 MPEG-2 transport stream . 506
14.5.3 CRC error detection . 506
14.5.4 Audio sample truncation . 507
14.6 Multi-stream delivery and interface . 507
© ISO/IEC 2025 – All rights reserved
vi
ISO/IEC 23008-3:2025(en)
14.7 Carriage of generic data . 510
14.7.1 Syntax . 510
14.7.2 Semantics . 511
14.7.3 Processing at the MPEG-H 3D audio decoder . 512
15 Metadata audio elements (MAE) . 512
15.1 General . 512
15.2 Syntax . 513
15.3 Semantics . 522
15.4 Definition of mae_metaDataElementIDs . 534
15.5 Loudness compensation after gain interactivity . 535
16 Loudspeaker distance compensation . 537
17 Interfaces to the MPEG-H 3D audio decoder . 538
17.1 General . 538
17.2 Interface for local setup information . 538
17.2.1 General . 538
17.2.2 WIRE output . 538
17.2.3 Syntax for local setup information . 539
17.2.4 Semantics for local setup information . 539
17.3 Interface for local loudspeaker setup and rendering. 540
17.3.1 General . 540
17.3.2 Syntax for local loudspeaker signalling . 540
17.3.3 Semantics for local loudspeaker signalling . 541
17.4 Interface for binaural room impulse responses (BRIRs) . 542
17.4.1 General . 542
17.4.2 Syntax of binaural renderer interface . 542
17.4.3 Semantics . 547
17.5 Interface for local screen size information . 551
17.5.1 General . 551
17.5.2 Syntax . 551
17.5.3 Semantics . 551
17.6 Interface for signaling of local zoom area . 552
17.6.1 General . 552
17.6.2 Syntax . 552
17.6.3 Semantics . 552
17.7 Interface for user interaction . 553
17.7.1 General . 553
17.7.2 Definition of user interaction categories . 553
17.7.3 Definition of an interface for user interaction . 554
17.7.4 Syntax of interaction interface . 555
17.7.5 Semantics of interaction interface . 556
17.8 Interface for loudness normalization and dynamic range control (DRC) . 558
17.9 Interface for scene displacement data . 558
17.9.1 General . 558
17.9.2 Definition of an interface for scene-displacement data . 559
17.9.3 Syntax of the scene displacement interface . 560
17.9.4 Semantics of the scene displacement interface . 560
17.10 Interfaces for channel-based, object-based, and HOA metadata and audio data . 561
17.10.1 General . 561
17.10.2 Expectations on external renderers . 561
17.10.3 Object-based metadata and audio data (object output interface) . 561
17.10.4 Channel-based metadata and audio data . 569
17.10.5 HOA metadata and audio data . 573
17.10.6 Audio PCM data . 577
© ISO/IEC 2025 – All rights reserved
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ISO/IEC 23008-3:2025(en)
17.11 Interface for positional scene displacement data . 577
17.11.1 General . 577
17.11.2 Syntax of the positional scene displacement interface . 578
17.11.3 Semantics of the positional scene displacement interface . 578
17.11.4 Processing . 578
18 Application and processing of local setup information and interaction data and
scene displacement data . 579
18.1 Element metadata preprocessing . 579
18.1.1 General information . 579
18.1.2 Initialization . 580
18.1.3 Processing loop . 581
18.1.4 Element routing . 585
18.2 Interactivity limitations and restrictions . 585
18.2.1 General information . 585
18.2.2 WIRE interactivity . 585
18.2.3 Position interactivity . 586
18.2.4 Screen-related element remapping and object remapping for zooming . 586
18.2.5 Closest loudspeaker playout . 587
18.3 Screen-related element remapping . 587
18.4 Screen-related adaptation and zooming for higher order ambisonics (HOA) . 590
18.5 Object remapping for zooming . 592
18.6 Determination of the closest loudspeaker . 594
18.7 Determination of a list of loudspeakers for conditioned closest loudspeaker
playback .
...

ISO/IEC 23008-3:202x(E)
ISO/IEC JTC 1/SC 29/WG 6
Secretariat:  JISC
Information technology — High efficiency coding and media
delivery in heterogeneous environments — Part 3: 3D audio
Technologies de l'information — Codage à haute efficacité et livraison des medias dans des
environnements hétérogènes — Partie 3: Audio 3D
i
ISO/IEC DIS 23008-3:2024(E2025(en)
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
[e-mail]
www.iso.org
© ISO/IEC 20242025 – All rights reserved
ii
ISO/IEC DIS 23008-3:2024(E2025(en)
Contents Page
Foreword . xiii
Introduction . xiv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols, abbreviated terms and mnemonicsconventions . 2
3.1 Terms, and definitions, symbols and abbreviated terms. 2
3.2 MnemonicsSymbols, abbreviated terms and conventions . 2
4 Technical overview . 2
4.1 Decoder block diagram . 2
4.2 Overview over the codec building blocks . 3
4.3 Efficient combination of decoder processing blocks in the time domain and QMF
domain . 6
4.4 Rule set for determining processing domains . 9
4.4.1 Audio core codec processing domain . 9
4.4.2 Mixing . 10
4.4.3 DRC-1 Operation domains (DRC in rendering context) . 10
4.4.4 Audio core codec interface domain to rendering . 10
4.4.5 Rendering context . 10
4.4.6 Post-processing context . 11
4.4.7 End-of-chain context . 11
4.5 Sample rate converter . 11
4.6 Decoder delay . 11
4.7 Contribution mode of MPEG-H 3D audio . 12
4.8 MPEG-H 3D audio profiles and levels . 12
4.8.1 General . 12
4.8.2 Profiles . 13
5 MPEG-H 3D audio core decoder . 27
5.1 Definitions . 27
5.1.1 Joint stereo . 27
5.1.2 MPEG surround based stereo (MPS 212) . 28
5.2 Syntax . 28
5.2.1 General . 28
5.2.2 Decoder configuration . 28
5.2.3 MPEG-H 3D audio core bitstream payloads . 51
5.3 Data structure . 72
5.3.1 General . 72
5.3.2 General configuration data elements . 72
5.3.3 Loudspeaker configuration data elements . 75
5.3.4 Core decoder configuration data elements . 77
5.3.5 Downmix matrix data elements . 81
5.3.6 HOA rendering matrix data elements . 84
5.3.7 Signal group information elements . 87
5.3.8 Low frequency enhancement (LFE) channel element, mpegh3daLfeElement() . 87
5.3.9 Compatible profile and levels sets. 88
5.4 Configuration element descriptions . 88
5.4.1 General . 88
5.4.2 Downmix configuration . 88
5.4.3 HOA rendering matrix configuration . 94
5.5 Tool descriptions . 98
© ISO/IEC 20242025 – All rights reserved
iii
ISO/IEC DIS 23008-3:2024(E2025(en)
5.5.1 General . 98
5.5.2 Quad channel element. 98
5.5.3 Transform splitting . 100
5.5.4 MPEG surround for mono to stereo upmixing . 107
5.5.5 Enhanced noise filling . 110
5.5.6 Audio pre-roll . 134
5.5.7 Fullband LPD . 137
5.5.8 Time-domain bandwidth extension . 148
5.5.9 LPD stereo coding . 161
5.5.10 Multichannel coding tool . 169
5.5.11 Filterbank and block switching . 179
5.5.12 Frequency domain prediction . 180
5.5.13 Long-term postfilter . 183
5.5.14 Tonal component coding . 188
5.5.15 Internal channel on MPS212 for low complexity format conversion . 198
5.5.16 High resolution envelope processing (HREP) tool. 210
5.6 Buffer requirements . 216
5.6.1 Minimum decoder input buffer . 216
5.6.2 Bit reservoir . 216
5.6.3 Maximum bit rate . 217
5.7 Stream access point requirements and inter-frame dependency . 217
6 Dynamic range control and loudness processing . 218
6.1 General . 218
6.2 Description . 218
6.3 Syntax . 219
6.3.1 Loudness metadata . 219
6.3.2 Dynamic range control metadata . 219
6.3.3 Data elements . 220
6.4 Decoding process . 222
6.4.1 General . 222
6.4.2 Dynamic range control . 224
6.4.3 Usage of downmixId in MPEG-H . 224
6.4.4 DRC set selection process . 225
6.4.5 DRC-1 for SAOC 3D Content . 227
6.4.6 DRC-1 for HOA content . 228
6.4.7 Loudness normalization . 229
6.4.8 Peak limiter . 229
6.4.9 Time-synchronization of DRC gains . 230
6.4.10 Default parameters . 230
7 Object metadata decoding . 230
7.1 General . 230
7.2 Description . 230
7.3 Syntax . 231
7.3.1 Object metadata configuration . 231
7.3.2 Top level object metadata syntax . 232
7.3.3 Subsidiary payloads for efficient object metadata decoding . 233
7.3.4 Subsidiary payloads for object metadata decoding with low delay . 238
7.3.5 Enhanced object metadata configuration . 244
7.4 Data structure . 247
7.4.1 Definition of ObjectMetadataConfig() payloads . 247
7.4.2 Efficient object metadata decoding . 247
7.4.3 Object metadata decoding with low delay . 255
7.4.4 Enhanced object metadata . 260
© ISO/IEC 20242025 – All rights reserved
iv
ISO/IEC DIS 23008-3:2024(E2025(en)
8 Object rendering . 263
8.1 Description . 263
8.2 Terms and definitions . 263
8.3 Input data . 264
8.4 Processing . 265
8.4.1 General remark . 265
8.4.2 Imaginary loudspeakers . 265
8.4.3 Dividing the loudspeaker setup into a triangle mesh . 266
8.4.4 Rendering algorithm . 268
9 SAOC 3D . 272
9.1 Description . 272
9.2 Definitions . 272
9.3 Delay and synchronization . 274
9.4 Syntax . 274
9.4.1 Payloads for SAOC 3D . 274
9.4.2 Definition of SAOC 3D payloads . 278
9.5 SAOC 3D processing . 280
9.5.1 Compressed data stream decoding and dequantization of SAOC 3D data . 280
9.5.2 Time/frequency transforms . 280
9.5.3 Signals and parameters . 281
9.5.4 SAOC 3D decoding . 283
9.5.5 Dual mode . 288
10 Generic loudspeaker rendering/format conversion . 288
10.1 Description . 288
10.2 Definitions . 290
10.2.1 General remarks . 290
10.2.2 Variable definitions . 290
10.3 Processing . 290
10.3.1 Application of transmitted downmix matrices . 290
10.3.2 Application of transmitted equalizer settings . 295
10.3.3 Downmix processing involving multiple channel groups . 295
10.3.4 Initialization of the format converter . 296
10.3.5 Audio signal processing . 312
11 Immersive loudspeaker rendering/format conversion . 318
11.1 Description . 318
11.2 Syntax . 320
11.3 Definitions . 320
11.3.1 General remarks . 320
11.3.2 Variable definitions . 321
11.4 Processing . 322
11.4.1 Initialization of the format converter . 322
11.4.2 Audio signal processing . 365
12 Higher order ambisonics (HOA) . 372
12.1 Technical overview . 372
12.1.1 Block diagram . 372
12.1.2 Overview of the decoder tools . 373
12.2 Syntax . 375
12.2.1 Configuration of HOA elements . 375
12.2.2 Payloads of HOA elements . 379
12.3 Data structure . 392
12.3.1 Definitions of HOA Config . 392
12.3.2 Syntax of getSubbandBandwidths() . 396
12.3.3 Definitions of HOA payload . 397
© ISO/IEC 20242025 – All rights reserved
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ISO/IEC DIS 23008-3:2024(E2025(en)
12.4 HOA tool description . 405
12.4.1 HOA frame converter . 405
12.4.2 Spatial HOA decoding . 422
12.4.3 HOA renderer . 451
12.4.4 Layered coding for HOA . 460
13 Binaural renderer . 463
13.1 General . 463
13.2 Frequency-domain binaural renderer . 463
13.2.1 General . 463
13.2.2 Definitions . 465
13.2.3 Parameterization of binaural room impulse responses . 469
13.2.4 Frequency-domain binaural processing . 481
13.3 Time-domain binaural renderer . 488
13.3.1 General . 488
13.3.2 Definitions . 489
13.3.3 Parameterization of binaural room impulse responses . 491
13.3.4 Time-domain binaural processing . 495
14 MPEG-H 3D audio stream (MHAS) . 496
14.1 Overview . 496
14.2 Syntax . 497
14.2.1 Main MHAS syntax elements . 497
14.2.2 Subsidiary MHAS syntax elements . 499
14.3 Semantics . 499
14.3.1 mpeghAudioStreamPacket() . 499
14.3.2 MHASPacketPayload() . 500
14.3.3 Subsidiary MHAS packets . 502
14.4 Description of MHASPacketTypes . 502
14.4.1 PACTYP_FILLDATA . 502
14.4.2 PACTYP_MPEGH3DACFG . 502
14.4.3 PACTYP_MPEGH3DAFRAME . 503
14.4.4 PACTYP_SYNC . 503
14.4.5 PACTYP_SYNCGAP . 503
14.4.6 PACTYP_MARKER . 503
14.4.7 PACTYP_CRC16 and PACTYP_CRC32 . 504
14.4.8 PACTYP_DESCRIPTOR . 504
14.4.9 PACTYP_USERINTERACTION . 504
14.4.10 PACTYP_LOUDNESS_DRC . 505
14.4.11 PACTYP_BUFFERINFO . 505
14.4.12 PACTYP_GLOBAL_CRC16 and PACTYP_ GLOBAL_CRC32 . 505
14.4.13 PACTYP_AUDIOTRUNCATION . 505
14.4.14 PACTYP_AUDIOSCENEINFO . 506
14.4.15 PACTYP_EARCON . 507
14.4.16 PACTYP_PCMCONFIG . 507
14.4.17 PACTYP_PCMDATA . 507
14.4.18 PACTYP_LOUDNESS. 507
14.4.19 MHASPacketType specific requirements for MHASPacketLabel . 508
14.5 Application examples . 509
14.5.1 Light-weighted broadcast . 509
14.5.2 MPEG-2 transport stream . 509
14.5.3 CRC error detection . 510
14.5.4 Audio sample truncation . 510
14.6 Multi-stream delivery and interface . 510
14.7 Carriage of generic data . 513
14.7.1 Syntax . 513
© ISO/IEC 20242025 – All rights reserved
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14.7.2 Semantics . 514
14.7.3 Processing at the MPEG-H 3D audio decoder . 515
15 Metadata audio elements (MAE) . 515
15.1 General . 515
15.2 Syntax . 516
15.3 Semantics . 525
15.4 Definition of mae_metaDataElementIDs . 538
15.5 Loudness compensation after gain interactivity . 539
16 Loudspeaker distance compensation . 541
17 Interfaces to the MPEG-H 3D audio decoder . 542
17.1 General . 542
17.2 Interface for local setup information . 542
17.2.1 General . 542
17.2.2 WIRE output . 542
17.2.3 Syntax for local setup information . 543
17.2.4 Semantics for local setup information . 543
17.3 Interface for local loudspeaker setup and rendering. 544
17.3.1 General . 544
17.3.2 Syntax for local loudspeaker signalling . 544
17.3.3 Semantics for local loudspeaker signalling . 545
17.4 Interface for binaural room impulse responses (BRIRs) . 546
17.4.1 General . 546
17.4.2 Syntax of binaural renderer interface . 546
17.4.3 Semantics . 551
17.5 Interface for local screen size information . 555
17.5.1 General . 555
17.5.2 Syntax . 555
17.5.3 Semantics . 555
17.6 Interface for signaling of local zoom area . 556
17.6.1 General . 556
17.6.2 Syntax . 556
17.6.3 Semantics . 557
17.7 Interface for user interaction . 557
17.7.1 General . 557
17.7.2 Definition of user interaction categories . 557
17.7.3 Definition of an interface for user interaction . 558
17.7.4 Syntax of interaction interface . 559
17.7.5 Semantics of interaction interface . 560
17.8 Interface for loudness normalization and dynamic range control (DRC) . 562
17.9 Interface for scene displacement data . 563
17.9.1 General . 563
17.9.2 Definition of an interface for scene-displacement data . 563
17.9.3 Syntax of the scene displacement interface . 564
17.9.4 Semantics of the scene displacement interface . 564
17.10 Interfaces for channel-based, object-based, and HOA metadata and audio data . 565
17.10.1 General . 565
17.10.2 Expectations on external renderers . 565
17.10.3 Object-based metadata and audio data (object output interface) . 565
17.10.4 Channel-based metadata and audio data . 573
17.10.5 HOA metadata and audio data . 578
17.10.6 Audio PCM data . 582
17.11 Interface for positional scene displacement data . 583
17.11.1 General . 583
© ISO/IEC 20242025 – All rights reserved
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17.11.2 Syntax of the positional scene displacement interface . 583
17.11.3 Semantics of the positional scene displacement interface . 583
17.11.4 Processing . 584
18 Application and processing of local setup information and interaction data and scene
displacement data . 584
18.1 Element metadata preprocessing . 584
18.2 Interactivity limitations and restrictions . 590
18.2.1 General information . 590
18.2.2 WIRE interactivity . 590
18.2.3 Position interactivity . 591
18.2.4 Screen-related element remapping and object remapping for zooming . 591
18.2.5 Closest loudspeaker playout . 592
18.3 Screen-related element remapping . 592
18.4 Screen-related adaptation and zooming for higher order ambisonics (HOA) . 595
18.5 Object remapping for zooming . 597
18.6 Determination of the closest loudspeaker . 599
18.7 Determination of a list of loudspeakers for conditioned closest loudspeaker playback 599
18.8 Processing of scene displacement angles for channels and objects (CO) . 601
18.9 Processing of scene displacement angles for scene-based content (HOA) . 603
18.10 Determination of a reduc
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