Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 1: General

IEC 61937-1:2021 is available as IEC 61937-1:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61937-1:2021 applies to the digital audio interface using the IEC 60958 series for the conveying of non-linear PCM encoded audio bitstreams.
It describes the way in which this digital interface can be used in consumer applications. The professional mode is not considered within the scope of this document.
IEC 61937-1:2021 cancels and replaces the second edition published in 2007, and amendment 1 published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) Activation of Pe field;
b) Enhanced usage of channel status bits.
c) Addition of Annex B.

Audionumérique - Interface pour les flux de bits audio à codage MIC non linéaire conformément à l'IEC 60958 - Partie 1: Généralités

IEC 61937-1:2021 est disponible sous forme de IEC 61937-1:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 61937-1:2021 s'applique à l'interface audionumérique conforme à la série IEC 60958 pour l'acheminement des flux de bits audio à codage MIC non linéaire. Elle décrit comment cette interface numérique peut être utilisée dans les applications grand public. Le domaine d'application du présent document ne couvre pas le mode professionnel. L'IEC 61937-1:2021 annule et remplace la deuxième édition parue en 2007 et l'Amendement 1:2011. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) activation du champ Pe;
b) utilisation élargie de la voie de signalisation;
c) ajout de l'Annexe B.

General Information

Status
Published
Publication Date
23-Feb-2021
Current Stage
PPUB - Publication issued
Completion Date
24-Feb-2021
Ref Project

Buy Standard

Standard
IEC 61937-1:2021 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 1: General
English and French language
48 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

IEC 61937-1
Edition 3.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Digital audio – Interface for non-linear PCM Encoded audio bitstreams applying
IEC 60958 –
Part 1: General
Audionumérique – Interface pour les flux de bits audio à codage MIC non
linéaire selon l'IEC 60958 –
Partie 1: Généralités
IEC 61937-1:2021-02(en-fr)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2021 IEC, Geneva, Switzerland

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.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite

ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie

et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des

questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez

les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes

International Standards for all electrical, electronic and related technologies.
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

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

IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch

The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the

variety of criteria (reference number, text, technical publications previews. With a subscription you will always

committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.

and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC

La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des

Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC

Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la

plus récente, un corrigendum ou amendement peut avoir été publié.
Recherche de publications IEC - IEC online collection - oc.iec.ch

webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez

La recherche avancée permet de trouver des publications IEC gratuitement tous les aperçus des publications. Avec un

en utilisant différents critères (numéro de référence, texte, abonnement, vous aurez toujours accès à un contenu à jour

comité d’études, …). Elle donne aussi des informations sur adapté à vos besoins.
les projets et les publications remplacées ou retirées.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
Le premier dictionnaire d'électrotechnologie en ligne au
Restez informé sur les nouvelles publications IEC. Just
monde, avec plus de 22 000 articles terminologiques en
Published détaille les nouvelles publications parues.
anglais et en français, ainsi que les termes équivalents dans
Disponible en ligne et une fois par mois par email.
16 langues additionnelles. Egalement appelé Vocabulaire
Electrotechnique International (IEV) en ligne.
Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
---------------------- Page: 2 ----------------------
IEC 61937-1
Edition 3.0 2021-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Digital audio – Interface for non-linear PCM Encoded audio bitstreams applying
IEC 60958 –
Part 1: General
Audionumérique – Interface pour les flux de bits audio à codage MIC non
linéaire selon l'IEC 60958 –
Partie 1: Généralités
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.160.30 ISBN 978-2-8322-9429-1

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61937-1:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms, definitions, and presentation ................................................................................ 6

3.1 Terms and definitions .............................................................................................. 6

3.2 Presentation convention .......................................................................................... 8

4 General description ......................................................................................................... 8

5 Interface format ............................................................................................................... 8

6 Mapping of the audio bitstream on to IEC 60958 .............................................................. 9

6.1 Coding of the bitstream ........................................................................................... 9

6.2 Burst-payload ....................................................................................................... 14

6.3 Stuffing ................................................................................................................. 15

7 Format of data-bursts .................................................................................................... 15

7.1 General ................................................................................................................. 15

7.2 Pause data-burst .................................................................................................. 16

7.3 Audio data-bursts .................................................................................................. 19

7.4 Null data-burst ...................................................................................................... 19

Annex A (normative) Channel status when IEC 60958 is used in consumer

applications .......................................................................................................................... 20

Annex B (informative) Monaural linear PCM audio sample simultaneous transferred

with non-linear PCM encoded audio bitstream ...................................................................... 21

Figure 1 – IEC 60958 interface format .................................................................................... 9

Figure 2 – Data-burst format ................................................................................................. 11

Figure 3 – Burst-preamble .................................................................................................... 11

Figure 4 – Burst-preamble with extended preamble .............................................................. 13

Figure 5 – Length of the burst-payload specified by Pd ......................................................... 14

Figure 6 – Burst spacing ....................................................................................................... 15

Figure 7 – Flow chart of transmission of a bitstream ............................................................. 16

Figure 8 – Bridging gaps in-between data-bursts with three pause data-bursts ..................... 17

Figure 9 – Data-burst format of the data-type pause ............................................................. 18

Figure 10 – Null data-burst ................................................................................................... 19

Figure B.1 – Frame and Block structure ................................................................................ 21

Figure B.2 – Example 1: Frame and Block structure @ 48 kHz IEC 60958 frame rate ........... 22

Figure B.3 – Example 2: Frame and Block structure @ 192 kHz IEC 60958 frame rate ......... 22

Table 1 – Bit allocation of the IEC 60958 frame ...................................................................... 9

Table 2 – Bit allocation of data-burst in IEC 60958 subframes .............................................. 10

Table 3 – Burst-preamble words ........................................................................................... 12

Table 4 – Bit map of burst-preambles ................................................................................... 12

Table 5 – Fields of burst-info ................................................................................................ 12

Table 6 – Burst-preamble words ........................................................................................... 13

Table 7 – Fields of Pe (extended data-type) .......................................................................... 13

---------------------- Page: 4 ----------------------
IEC 61937-1:2021 © IEC 2021 – 3 –

Table 8 – Fields of Pf ............................................................................................................ 13

Table 9 – Values of data-type-dependent info of the pause data-burst .................................. 18

Table 10 – Burst-payload of pause data-burst ....................................................................... 18

Table 11 – Fields of a null data-burst .................................................................................... 19

Table A.1 – Allocation of the channel status bits ................................................................... 20

Table B.1 – Relationship between sampling frequency for monaural linear PCM and

IEC 60958 frame rate for non-linear PCM ............................................................................. 23

---------------------- Page: 5 ----------------------
– 4 – IEC 61937-1:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –
Part 1: General
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

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.

IEC 61937-1 has been prepared by technical area 20: Analogue and digital audio, of IEC

technical committee 100: Audio, video and multimedia systems and equipment. It is an

International Standard.

This third edition cancels and replaces the second edition published in 2007, and

amendment 1 published in 2011. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) Activation of Pe field;
b) Enhanced usage of channel status bits.
c) Addition of Annex B.
---------------------- Page: 6 ----------------------
IEC 61937-1:2021 © IEC 2021 – 5 –
The text of this International Standard is based on the following documents:
Draft Report on voting
100/3447/CDV 100/3522/RVC

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,

available at www.iec.ch/members_experts/refdocs. The main document types developed by

IEC are described in greater detail at www.iec.ch/standardsdev/publications.

The list of all the parts of IEC 61937, 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 document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 7 ----------------------
– 6 – IEC 61937-1:2021 © IEC 2021
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –
Part 1: General
1 Scope

This part of IEC 61937 applies to the digital audio interface using the IEC 60958 series for the

conveying of non-linear PCM encoded audio bitstreams.

It describes the way in which this digital interface can be used in consumer applications.

The professional mode is not considered within the scope of this document.
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.
IEC 60958-1, Digital audio interface – Part 1: General
IEC 60958-3, Digital audio interface – Part 3: Consumer applications
IEC 60958-5, Digital audio interface – Part 5: Consumer application enhancement

IEC 61937-2, Digital audio – Interface for non-linear PCM encoded audio bitstreams applying

IEC 60958 – Part 2: Burst-info
3 Terms, definitions, and presentation

For the purposes of this document, the following terms, definitions, and presentation

convention 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 http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
audio data-burst
data-burst with an encoded audio frame as burst-payload
3.1.2
audio data-word
16-bit data word
---------------------- Page: 8 ----------------------
IEC 61937-1:2021 © IEC 2021 – 7 –
3.1.3
audio frame
fixed number of audio samples

Note 1 to entry: The number of samples in an audio frame is dependent on the particular encoding system that is

used to encode the audio frame into the encoded audio frame.
3.1.4
audio gap

period in the sequence of baseband audio samples where valid samples of audio are not

available
3.1.5
bitstream
non-linear PCM encoded audio source, represented in a sequence of bits

Note 1 to entry: In this interface, the bitstream consists of a sequence of data-bursts.

3.1.6
data-burst

packet of data, including the burst-preamble, to be transmitted across the interface

3.1.7
burst-payload
information content of the data-burst
3.1.8
burst-preamble

header for the data-burst, containing synchronization, and information about the data

contained in the burst-payload
3.1.9
data-type
reference to the type of payload of the data-bursts
3.1.10
encoded audio frame
minimum decodable unit of an encoded data sequence

Note 1 to entry: Each encoded audio frame is the encoded representation of a fixed number of audio samples (for

each original audio channel). The number of samples that are encoded into an encoded audio frame depends on

the particular encoding system that is used to encode the audio frame into the encoded audio frame.

3.1.11
idle

state in which the interface is not used to convey any sequence of data-bursts or PCM data

Note 1 to entry: The channel status data is still active (bit b1 is set to '1' when further non-linear PCM encoded

audio is anticipated; see Figure 7).
3.1.12
length-code

code indicating the length of the data-burst-payload in bits, bytes or 8-byte units

3.1.13
repetition period

period between the reference point of the current data-burst and the reference point of the

immediately following data-burst of the same data-type
---------------------- Page: 9 ----------------------
– 8 – IEC 61937-1:2021 © IEC 2021
3.1.14
sampling frequency

sampling frequency of the encoded PCM audio samples (i.e. before encoding and after

decoding)
3.1.15
sampling period

time period related to the sampling frequency of the PCM audio samples, represented in the

encoded bitstream
3.1.16
stuffing
occupying the unused data capacity of the interface
3.1.17
stuffing subframe
occupying the unused data capacity in 16-bit audio data words
3.1.18
stream gap

period within the encoded audio bitstream without any audio frame; a discontinuity in the

bitstream

Note 1 to entry: Typically, a stream gap will occur between encoded audio frames.

3.2 Presentation convention
3.2.1
F872h
value 'F872' in hexadecimal format
4 General description

The format of the IEC 60958 interface consists of a sequence of IEC 60958 subframes. Each

IEC 60958 subframe is normally used to carry one linear PCM sample, but may also be used

to convey data. The non-linear PCM encoded audio bitstreams to be transported over this

interface are formed into a sequence of data-bursts.

Each data-burst consists of a 64-bit burst-preamble, followed by the burst-payload. The burst-

preamble consists of a sync-word, information about the burst-payload and a bitstream-

number.

The interface may convey one or more bitstreams. Each type of bitstream may impose a

particular requirement for the repetition period for the data-bursts that make up the bitstream

(see Clause 7).

The 16 bits of a data-burst are placed in time-slots 12 to 27 of an IEC 60958 subframe. Both

odd and even IEC 60958 subframes (channel 1, channel 2) are simultaneously used to carry

32 bits of data. This allows IEC 60958, in the consumer mode, to convey either two-channel

linear PCM audio, or a set of non-linear PCM encoded bitstreams (alternating data words), but

not both simultaneously.
5 Interface format
The interface format as defined in IEC 60958-1 and IEC 60958-3 is used.
---------------------- Page: 10 ----------------------
IEC 61937-1:2021 © IEC 2021 – 9 –
6 Mapping of the audio bitstream on to IEC 60958
6.1 Coding of the bitstream
6.1.1 General

The non-linear PCM encoded audio bitstream is transferred using the basic 16-bit data area of

the IEC 60958 subframes, i.e. in time-slots 12 to 27 (see Figure 1 and Table 1). Because the

non-linear PCM encoded audio bitstream to be transported is at a lower data rate than that

supported by the IEC 60958 interface, the audio bitstream is broken into a sequence of

discrete data-bursts, and stuffing between the data-bursts is necessary (see 6.3).

Each data-burst contains data of an encoded audio frame that is the encoded representation

of a fixed number of audio samples per PCM audio channel. The number of samples to be

encoded into an encoded audio frame depends on the particular encoding system.

It is possible for this interface to simultaneously convey multiple non-linear PCM encoded

audio bitstreams. One of the applications of this capability would be to convey both a main

audio service and an associated audio service.
Figure 1 – IEC 60958 interface format
Table 1 – Bit allocation of the IEC 60958 frame
Field IEC 60958 time-slot Value
0 to 3 Preamble IEC 60958 preamble
4 to 7 Auxiliary field Not used, all "0" or partial of linear PCM
8 to 11 Unused data bits Not used, all "0" or partial of linear PCM
12 to 27 16-bit data Sections of the bitstream
28 Validity flag According to IEC 60958
29 User data According to IEC 60958
30 Channel status According to IEC 60958
31 Parity bit According to IEC 60958
---------------------- Page: 11 ----------------------
– 10 – IEC 61937-1:2021 © IEC 2021
6.1.2 Bit map of bitstream

The method of placing the data into the IEC 60958 bitstream is to format the data to be

transmitted into data-bursts and to send each data-burst in a continuous sequence of

IEC 60958 frames (see Table 2).
Table 2 – Bit allocation of data-burst in IEC 60958 subframes
Bit of subframes
Subframe MSB LSB
b27 b26 b25 ………… b14 b13 b12
Frame 0; subframe B or M 0 1 14 15
Frame 0; subframe W 16 17 30 31
Frame 1; subframe B or M 32 33 46 47
Frame 1; subframe W 48 49 62 63
Frame 2; subframe B or M 64 65 78 79
-------------------- ------------
Last subframe B or M of data-burst n – 32 n – 31 n – 18 n – 17
Last subframe W of data-burst n – 16 n – 15 n – 2 n – 1

Considering the data within an IEC 60958 subframe as a 16-bit word out of a serial stream of

bits, the first bit of the burst-payload in a data-burst would occupy the MSB of subframe 1

(time-slot 27), and the 32 bit would occupy the LSB (or what would be the LSB for 16-bit

PCM audio) of subframe 2 (time-slot 12). The next 32 bits of the burst-payload would occupy

the next IEC 60958 frame. The last data bits of the audio data-burst might occupy only a

fraction of the last frame. Any unused bits in the last frame will be ignored by the receiver. In

the case where the audio data-burst contains a multiple of 16 bits, all used IEC 60958 sub-

frames are completely filled. When it is not a multiple of 16 bits, the bits of the burst-payload

to be conveyed in the last IEC 60958 subframe will be MSB aligned; the remaining bits shall

be stuffed with zeros.
6.1.3 IEC 60958 validity flag

It is recommended to set the validity bit to a logical '1'. This is intended to prevent accidental

decoding of non-audio data to analogue before a complete channel status block is received.

6.1.4 IEC 60958 channel status bit 1

The purpose of channel status bit 1 is to indicate if IEC 60958 is used to convey linear PCM

or to indicate that the interface is used for other purposes (see Annex A). This bit shall be set

to '1' when IEC 60958 is used to convey non-linear PCM encoded audio bitstreams.
6.1.5 Symbol frequency

When the IEC 60958 bitstream conveys linear PCM audio, the symbol frequency is 64 times

the PCM sampling frequency (32 time-slots per PCM sample, times two channels). When a

non-linear PCM encoded audio bitstream is conveyed by the interface, the symbol frequency

is normally 64 times the sampling rate of the encoded audio within that bitstream, and other

times should be referred to each parts of IEC 61937.
6.1.6 The format of the data-bursts

Each data-burst contains a burst-preamble consisting of four 16-bit words (Pa, Pb, Pc and Pd)

followed by the burst-payload that contains data of an encoded audio frame (see Figure 2).

---------------------- Page: 12 ----------------------
IEC 61937-1:2021 © IEC 2021 – 11 –
Figure 2 – Data-burst format

The repetition period of these bursts is defined as the length between the reference points R

(measured in IEC 60958 frames) of one data-burst and the next data-burst (with the same

bit-stream-number). The data representing each individual encoded audio frame is typically

specified to be packaged into a single individual data-burst, with a repetition period

(measured in IEC 60958 frames) for that data-burst equal to the number of encoded audio

samples of each channel contained within that encoded audio frame.

It is possible for a number of data-bursts representing multiple bitstreams to be interleaved on

the interface. When more than one non-linear PCM encoded audio bitstreams are transmitted

through the same interface, the audio sampling rates of these bitstreams are identical to each

other.
6.1.7 Burst-preamble

The burst-preamble consists of four mandatory fields. Pa and Pb represent a synchronization

word. Pc gives information about the type of data, and some information/control for the

receiver. Pd gives the length of the burst-payload, limited to 65 535 bits if the length of Pd is

given in bits, limited to 65 535 bytes if the length of Pd is given in bytes, or limited to 524 280

bytes if the length of Pd is given in 8-byte units.

The four preamble words are contained in two sequential IEC 60958 frames (see Figure 3).

The frame beginning the data-burst contains preamble word Pa in subframe 1, and Pb in

subframe 2. The next frame contains Pc in subframe 1 and Pd in subframe 2. When placed

into an IEC 60958 subframe, the MSB of a 16-bit burst-preamble word is placed into time-slot

27 and the LSB is placed into time-slot 12 (see Table 3 and Table 4).
Figure 3 – Burst-preamble
---------------------- Page: 13 ----------------------
– 12 – IEC 61937-1:2021 © IEC 2021
Table 3 – Burst-preamble words
Value
Preamble word Length of field Contents
MSB ... LSB
Pa 16-bit Sync word 1 F872h
Pb 16-b
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.