ISO/IEC 23003-4:2020

Information technology — MPEG audio technologies — Part 4: Dynamic range control

This document specifies technology for loudness and dynamic range control. It is applicable to most MPEG audio technologies. It offers flexible solutions to efficiently support the widespread demand for technologies such as loudness normalization and dynamic range compression for various playback scenarios.

Technologies de l'information — Technologies audio MPEG — Partie 4: Contrôle de gamme dynamique

General Information

• Status: Published
• Publication Date: 03-Jun-2020
• 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: 9599 - Withdrawal of International Standard
• Due Date: 19-Mar-2025
• Completion Date: 19-Mar-2025

Relations

• Amended By: ISO/IEC 23003-4:2020/Amd 2:2023 - Information technology — MPEG audio technologies — Part 4: Dynamic range control — Amendment 2: Loudness leveling
• Effective Date: 02-Jul-2022
• Amended By: ISO/IEC 23003-4:2020/Amd 1:2022 - Information technology — MPEG audio technologies — Part 4: Dynamic range control — Amendment 1: Side chain normalization
• Effective Date: 21-Aug-2021
• Revised: ISO/IEC 23003-4:2025 - Information technology — MPEG audio technologies — Part 4: Dynamic range control
• Effective Date: 17-Feb-2024
• Revises: ISO/IEC 23003-4:2015 - Information technology — MPEG audio technologies — Part 4: Dynamic Range Control
• Effective Date: 02-Jun-2018
• Revises: ISO/IEC 23003-4:2015/Amd 2:2017 - Information technology — MPEG audio technologies — Part 4: Dynamic Range Control — Amendment 2: Reference software
• Effective Date: 02-Jun-2018
• Revises: ISO/IEC 23003-4:2015/Amd 1:2017 - Information technology — MPEG audio technologies — Part 4: Dynamic Range Control — Amendment 1: Parametric DRC, gain mapping and equalization tools
• Effective Date: 02-Jun-2018

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 23003-4
Second edition
2020-06
Information technology — MPEG
audio technologies —
Part 4:
Dynamic range control
Technologies de l'information — Technologies audio MPEG —
Partie 4: Contrôle de gamme dynamique
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and mnemonics. 1
3.1 Terms and definitions . 1
3.2 Mnemonics . 3
4 Symbols (and abbreviated terms) . 3
5 Technical overview . 4
6 DRC decoder . 6
6.1 DRC decoder configuration . 6
6.1.1 Overview . 6
6.1.2 Description of logical blocks . 7
6.1.3 Derivation of peak and loudness values. 12
6.2 Dynamic DRC gain payload . 16
6.3 DRC set selection . 16
6.3.1 Overview . 16
6.3.2 Pre-selection based on Signal Properties and Decoder Configuration . 17
6.3.3 Selection based on requests . 20
6.3.4 Final selection . 22
6.3.5 Applying multiple DRC sets . 23
6.3.6 Album mode . 23
6.3.7 Ducking. 23
6.3.8 Precedence . 24
6.4 Time domain DRC application . 24
6.4.1 Overview . 24
6.4.2 Framing . 24
6.4.3 Time resolution . 25
6.4.4 Time alignment . 25
6.4.5 Decoding . 26
6.4.6 Gain modifications and interpolation . 29
6.4.7 Spline interpolation . 35
6.4.8 Look-ahead in decoder . 36
6.4.9 Node reservoir . 37
6.4.10 Applying the compression . 38
6.4.11 Dynamic equalization . 41
6.4.12 Multi-band DRC filter bank . 43
6.5 Sub-band domain DRC . 47
6.6 Generation of DRC gain values at the decoder . 51
6.6.1 Overview . 51
6.6.2 Description of logical blocks . 52
6.6.3 Algorithmic details . 53
6.6.4 Combining parametric and non-parametric DRCs . 60
6.7 Loudness equalization support . 61
6.8 Equalization tool . 62
© ISO/IEC 2020 – All rights reserved iii

6.8.1 Overview . 62
6.8.2 EQ payloads . 62
6.8.3 EQ filter elements . 63
6.8.4 EQ set selection . 64
6.8.5 Application of EQ set . 64
6.9 Complexity management . 72
6.9.1 General . 72
6.9.2 DRC and downmixing complexity estimation . 72
6.9.3 EQ complexity estimation . 74
6.10 Loudness normalization . 75
6.10.1 Overview . 75
6.10.2 Loudness normalization based on target loudness . 76
6.11 DRC in streaming scenarios . 79
6.11.1 DRC configuration . 79
6.11.2 Error handling . 79
6.12 DRC configuration changes during active processing . 79
7 Syntax . 81
7.1 Syntax of DRC payload . 81
7.2 Syntax of DRC gain payload . 81
7.3 Syntax of static DRC payload . 82
7.4 Syntax of DRC gain sequence. 109
7.5 Syntax of parametric DRC tool. 110
7.6 Syntax of equalization tools . 117
8 Reference software . 131
8.1 Reference software structure . 131
8.1.1 General . 131
8.2 Bitstream decoding software . 131
8.2.1 General . 131
8.2.2 MPEG-D DRC decoding software . 132
9 Conformance . 132
9.1 General . 132
9.2 Conformance testing . 132
9.2.1 Conformance test data and test procedure . 132
9.2.2 Naming conventions . 134
9.2.3 File format definitions . 136
9.3 Encoder Conformance for MPEG-D DRC bitstreams . 138
9.3.1 Characteristics and test procedure . 138
9.3.2 Configuration payload . 139
9.3.3 Interface payload . 153
9.3.4 Frame Payload . 156
9.3.5 Requirements depending on profiles and levels .
...

INTERNATIONAL ISO/IEC
STANDARD 23003-4
Second edition
2020-06
Information technology — MPEG
audio technologies —
Part 4:
Dynamic range control
Technologies de l'information — Technologies audio MPEG —
Partie 4: Contrôle de gamme dynamique
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and mnemonics. 1
3.1 Terms and definitions . 1
3.2 Mnemonics . 3
4 Symbols (and abbreviated terms) . 3
5 Technical overview . 4
6 DRC decoder . 6
6.1 DRC decoder configuration . 6
6.1.1 Overview . 6
6.1.2 Description of logical blocks . 7
6.1.3 Derivation of peak and loudness values. 12
6.2 Dynamic DRC gain payload . 16
6.3 DRC set selection . 16
6.3.1 Overview . 16
6.3.2 Pre-selection based on Signal Properties and Decoder Configuration . 17
6.3.3 Selection based on requests . 20
6.3.4 Final selection . 22
6.3.5 Applying multiple DRC sets . 23
6.3.6 Album mode . 23
6.3.7 Ducking. 23
6.3.8 Precedence . 24
6.4 Time domain DRC application . 24
6.4.1 Overview . 24
6.4.2 Framing . 24
6.4.3 Time resolution . 25
6.4.4 Time alignment . 25
6.4.5 Decoding . 26
6.4.6 Gain modifications and interpolation . 29
6.4.7 Spline interpolation . 35
6.4.8 Look-ahead in decoder . 36
6.4.9 Node reservoir . 37
6.4.10 Applying the compression . 38
6.4.11 Dynamic equalization . 41
6.4.12 Multi-band DRC filter bank . 43
6.5 Sub-band domain DRC . 47
6.6 Generation of DRC gain values at the decoder . 51
6.6.1 Overview . 51
6.6.2 Description of logical blocks . 52
6.6.3 Algorithmic details . 53
6.6.4 Combining parametric and non-parametric DRCs . 60
6.7 Loudness equalization support . 61
6.8 Equalization tool . 62
© ISO/IEC 2020 – All rights reserved iii

6.8.1 Overview . 62
6.8.2 EQ payloads . 62
6.8.3 EQ filter elements . 63
6.8.4 EQ set selection . 64
6.8.5 Application of EQ set . 64
6.9 Complexity management . 72
6.9.1 General . 72
6.9.2 DRC and downmixing complexity estimation . 72
6.9.3 EQ complexity estimation . 74
6.10 Loudness normalization . 75
6.10.1 Overview . 75
6.10.2 Loudness normalization based on target loudness . 76
6.11 DRC in streaming scenarios . 79
6.11.1 DRC configuration . 79
6.11.2 Error handling . 79
6.12 DRC configuration changes during active processing . 79
7 Syntax . 81
7.1 Syntax of DRC payload . 81
7.2 Syntax of DRC gain payload . 81
7.3 Syntax of static DRC payload . 82
7.4 Syntax of DRC gain sequence. 109
7.5 Syntax of parametric DRC tool. 110
7.6 Syntax of equalization tools . 117
8 Reference software . 131
8.1 Reference software structure . 131
8.1.1 General . 131
8.2 Bitstream decoding software . 131
8.2.1 General . 131
8.2.2 MPEG-D DRC decoding software . 132
9 Conformance . 132
9.1 General . 132
9.2 Conformance testing . 132
9.2.1 Conformance test data and test procedure . 132
9.2.2 Naming conventions . 134
9.2.3 File format definitions . 136
9.3 Encoder Conformance for MPEG-D DRC bitstreams . 138
9.3.1 Characteristics and test procedure . 138
9.3.2 Configuration payload . 139
9.3.3 Interface payload . 153
9.3.4 Frame Payload . 156
9.3.5 Requirements depending on profiles and levels .
...