IEC 61937-3:2007

Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3 formats

IEC 61937-3:2007 describes the method used to convey non-linear PCM bitstreams encoded according to the AC-3 and enhanced AC-3 formats. This second edition cancels and replaces the first edition published in 2003. It contains the following significant technical changes. The definition of the audio data-burst required to deliver enhanced AC-3 bitstreams has been added. The definition of the latency of an enhanced AC-3 decoder has been added. The use of pause data-bursts when delivering enhanced AC-3 bitstreams has been added.

Audionumérique - Interface pour les flux de bits audio à codage MIC non linéaire conformément à la CEI 60958 - Partie 3: Flux de bits MIC non linéaire selon les formats AC-3 et AC-3 amélioré

La CEI 61937-3:2007 décrit la méthode utilisée pour acheminer des flux de bits MIC non linéaire codés selon les formats AC-3 et AC-3 amélioré. Cette seconde édition de la CEI 61937-3 annule et remplace la première édition parue en 2003. La présente édition contient les importantes modifications techniques suivantes par rapport à la précédente édition. La définition de la salve de données audio nécessaire pour délivrer des flux de bits au format AC-3 amélioré a été ajoutée. La définition de la latence d'un décodeur AC-3 amélioré a été ajoutée. L'utilisation de salves de données de type Pause lorsque des flux de bits au format AC-3 amélioré sont délivrés a été ajoutée.

General Information

• Status: Published
• Publication Date: 06-Nov-2007
• ICS: 33.160.30 - Audio systems
• Technical Committee: TC 100 - Audio, video and multimedia systems and equipment
• Drafting Committee: MT 61937-3 - TC 100/MT 61937-3
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 28-Jul-2017

Relations

• Revised: IEC 61937-3:2017 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3 formats
• Effective Date: 05-Sep-2023
• Revises: IEC 61937-3:2003 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 3: Non-linear PCM bitstreams according to the AC-3 format
• Effective Date: 05-Sep-2023
• Revises: IEC 61937-3:2003/COR1:2004 - Corrigendum 1 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 3: Non-linear PCM bitstreams according to the AC-3 format
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61937-3
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 –
Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3
formats
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

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IEC 61937-3
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 –
Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3
formats
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
M
ICS 33.160.30 ISBN 2-8318-9360-7

– 2 – 61937-3 © IEC:2007(E)
CONTENTS
FOREWORD.3

1 Scope.5
2 Normative references.5
3 Terms, definitions and abbreviations .5
3.1 Terms and definitions.5
3.2 Abbreviations.6
4 Mapping of the audio bitstream on to IEC 61937-1 .6
4.1 General .6
4.2 AC-3 and enhanced AC-3 burst-info.6
5 Format of AC-3 and enhanced AC-3 data-bursts .6
5.1 General .6
5.2 Pause data-burst .7
5.3 Audio data-bursts .7
5.3.1 AC-3 data .7
5.3.2 Latency of AC-3 decoding .8
5.3.3 Enhanced AC-3 data.9
5.3.4 Latency of the enhanced AC-3 decoder .10

Bibliography .13

Figure 1 – AC-3 data-burst, with reference point R .7
Figure 2 – Latency of AC-3 decoding.8
Figure 3 – Enhanced AC-3 data-burst.10
Figure 4 – Latency of enhanced AC-3 decoding .11

Table 1 – Fields of burst-info.6
Table 2 – Repetition period of the pause data-bursts .7
Table 3 – Data-type-dependent information when data-type = 1 .7
Table 4 – Data-type-dependent information when data-type = 21 .10
Table 5 – Frame repetition period and maximum data rate for enhanced AC-3
bitstreams.10

61937-3 © IEC:2007(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 3: Non-linear PCM bitstreams according to
the AC-3 and enhanced AC-3 formats

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61937-3 has been prepared by technical area 4: Digital system
interfaces, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
This second edition of IEC 61937-3 cancels and replaces the first edition published in 2003.
This edition contains the following significant technical changes with respect to the previous
edition.
a) The definition of the audio data-burst required to deliver enhanced AC-3 bitstreams has
been added.
b) The definition of the latency of an enhanced AC-3 decoder has been added.
c) The use of pause data-bursts when delivering enhanced AC-3 bitstreams has been added.

– 4 – 61937-3 © IEC:2007(E)
The text of this standard is based on the following documents:
CDV Report on voting
100/1207/CDV 100/1291/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The list of all the parts of the IEC 61937 series, under the general title Digital audio – Interface
for non-linear PCM encoded audio bitstreams applying IEC 60958, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

61937-3 © IEC:2007(E) – 5 –
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 3: Non-linear PCM bitstreams according to
the AC-3 and enhanced AC-3 formats

1 Scope
This part of IEC 61937 describes the method used to convey non-linear PCM bitstreams
encoded according to the AC-3 and enhanced AC-3 formats.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60958 (all parts), Digital audio interface
IEC 61937-1:2007, Digital audio interface for non-linear PCM encoded audio bitstreams
applying IEC 60958 – Part 1: General
IEC 61937-2:2007, Digital audio interface for non-linear PCM encoded audio bitstreams
applying IEC 60958 – Part 2: Burst-info
ATSC Standard A/52B, Digital Audio Compression (AC-3, E-AC-3), Rev. B
ETSI TS 102 366, Digital Audio Compression (AC-3, Enhanced AC-3)
3 Terms and definitions
For the purposes of this standard, the following terms, definitions and abbreviations apply.
3.1 Terms and definitions
3.1.1
latency
delay time of an external audio decoder to decode an AC-3 or enhanced AC-3 data burst,
defined as the sum of two values of the receiving delay time and the decoding delay time.
3.1.2
stream type
an enhanced AC-3 bitstream is constructed from one or more substreams, with each
substream being constructed from a sequence of frames. The stream type parameter of an
enhanced AC-3 frame identifies the type of substream of which the frame is a part

– 6 – 61937-3 © IEC:2007(E)
3.1.3
substream identification
substream identification parameter of an enhanced AC-3 frame which, in conjunction with the
stream type parameter, identifies the substream in the bitstream of which the enhanced AC-3
frame is a part
3.1.4
converter synchronization flag
flag used for synchronization by a device that converts an enhanced AC-3 bitstream to a
bitstream compliant with an AC-3 decoder and indicates that the first block in this enhanced
AC-3 frame will form the first block of the AC-3 frame output by the conversion process
3.1.5
block identification flag
if the stream type value of an enhanced AC-3 substream is two, indicating that the bitstream
has been converted from an AC-3 bitstream, this bit is set to 1 to indicate that the first block in
this enhanced AC-3 frame was the first block in the original standard AC-3 frame
3.2 Abbreviations
ATSC  Advanced Television Standards Committee
ETSI  European Telecommunication Standards Institute
IEC  International Electrotechnical Commission
ISO/IEC MPEG Moving Pictures Expert Group, a joint committee of ISO and IEC

4 Mapping of the audio bitstream on to IEC 61937-1
4.1 General
The coding of the bitstream and data-burst is in accordance with IEC 61937-1 and 61937-2.
4.2 AC-3 and enhanced AC-3 burst-info
The 16-bit burst-info contains information about the data which will be found in the data-burst
(see Table 1).
Table 1 – Fields of burst-info
Data- Sub- Contents Reference Repetition period of
type data-type point R data-burst measured in
IEC 60958 frames
Value of Value of
Pc bits Pc bi
...

IEC 61937-3 ®
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 –
Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3
formats
Audionumérique – Interface pour les flux de bits audio à codage MIC non
linéaire conformément à la CEI 60958 –
Partie 3: Flux de bits MIC non linéaire selon les formats AC-3 et AC-3 amélioré

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
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International Standards for all electrical, electronic and related technologies.

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latest edition, a corrigenda or an amendment might have been published.

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IEC 61937-3 ®
Edition 2.0 2007-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying

IEC 60958 –
Part 3: Non-linear PCM bitstreams according to the AC-3 and enhanced AC-3

formats
Audionumérique – Interface pour les flux de bits audio à codage MIC non

linéaire conformément à la CEI 60958 –

Partie 3: Flux de bits MIC non linéaire selon les formats AC-3 et AC-3 amélioré

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX M
ICS 33.160.30 ISBN 978-2-83220-522-8

– 2 – 61937-3  IEC:2007
CONTENTS
FOREWORD . 3

1 Scope . 5
2 Normative references. 5
3 Terms, definitions and abbreviations . 5
3.1 Terms and definitions . 5
3.2 Abbreviations . 6
4 Mapping of the audio bitstream on to IEC 61937-1 . 6
4.1 General . 6
4.2 AC-3 and enhanced AC-3 burst-info . 6
5 Format of AC-3 and enhanced AC-3 data-bursts . 6
5.1 General . 6
5.2 Pause data-burst . 7
5.3 Audio data-bursts . 7
5.3.1 AC-3 data . 7
5.3.2 Latency of AC-3 decoding . 8
5.3.3 Enhanced AC-3 data . 9
5.3.4 Latency of the enhanced AC-3 decoder . 10

Bibliography . 13

Figure 1 – AC-3 data-burst, with reference point R . 7
Figure 2 – Latency of AC-3 decoding . 8
Figure 3 – Enhanced AC-3 data-burst . 10
Figure 4 – Latency of enhanced AC-3 decoding . 11

Table 1 – Fields of burst-info . 6
Table 2 – Repetition period of the pause data-bursts . 7
Table 3 – Data-type-dependent information when data-type = 1 . 7
Table 4 – Data-type-dependent information when data-type = 21 . 10
Table 5 – Frame repetition period and maximum data rate for enhanced AC-3
bitstreams . 10

61937-3  IEC:2007 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 3: Non-linear PCM bitstreams according to
the AC-3 and enhanced AC-3 formats

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61937-3 has been prepared by technical area 4: Digital system
interfaces, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
This second edition of IEC 61937-3 cancels and replaces the first edition published in 2003.
This edition contains the following significant technical changes with respect to the previous
edition.
a) The definition of the audio data-burst required to deliver enhanced AC-3 bitstreams has
been added.
b) The definition of the latency of an enhanced AC-3 decoder has been added.
c) The use of pause data-bursts when delivering enhanced AC-3 bitstreams has been added.

– 4 – 61937-3  IEC:2007
This bilingual version (2012-12) corresponds to the monolingual English version, published in
2007-11. The text of this standard is based on the following documents:
CDV Report on voting
100/1207/CDV 100/1291/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The list of all the parts of the IEC 61937 series, under the general title Digital audio – Interface
for non-linear PCM encoded audio bitstreams applying IEC 60958, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
61937-3  IEC:2007 – 5 –
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 3: Non-linear PCM bitstreams according to
the AC-3 and enhanced AC-3 formats

1 Scop
...