IEC 61937-8:2006

Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 8: Non-linear PCM bitstreams according to the Windows Media Audio (WMA) Professional format

specifies the method for the digital audio interface specified in IEC 60958 to convey non-linear PCM bitstreams encoded in accordance with the WMA Professional format.

General Information

• Status: Published
• Publication Date: 24-Oct-2006
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: TC 100 - Audio, video and multimedia systems and equipment
• Current Stage: PPUB - Publication issued
• Start Date: 31-Dec-2006
• Completion Date: 25-Oct-2006

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD 61937-8
First edition
2006-10
Digital Audio –
Interface for non-linear PCM encoded
audio bitstreams applying IEC 60958 –
Part 8:
Non-linear PCM bitstreams according to the
Windows Media Audio (WMA) Professional format
Reference number
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
Consolidated editions
The IEC is now publishing consolidated versions of its publications. For example,
edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
base publication incorporating amendment 1 and the base publication incorporating
amendments 1 and 2.
Further information on IEC publications
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology. Information relating to
this publication, including its validity, is available in the IEC Catalogue of
publications (see below) in addition to new editions, amendments and corrigenda.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is also available from the following:
• IEC Web Site (www.iec.ch)
• Catalogue of IEC publications
The on-line catalogue on the IEC web site (www.iec.ch/searchpub) enables you to
search by a variety of criteria including text searches, technical committees
and date of publication. On-line information is also available on recently issued
publications, withdrawn and replaced publications, as well as corrigenda.
• IEC Just Published
This summary of recently issued publications (www.iec.ch/online_news/ justpub)
is also available by email. Please contact the Customer Service Centre (see
below) for further information.
• Customer Service Centre
If you have any questions regarding this publication or need further assistance,
please contact the Customer Service Centre:

Email: [e-mail]
Tel: [phone]
Fax: [phone]
INTERNATIONAL IEC
STANDARD 61937-8
First edition
2006-10
Digital Audio –
Interface for non-linear PCM encoded
audio bitstreams applying IEC 60958 –
Part 8:
Non-linear PCM bitstreams according to the
Windows Media Audio (WMA) Professional format
© IEC 2006 ⎯ Copyright - all rights reserved
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 the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale M
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – 61937-8 © IEC:2006(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 .5
3.3 Presentation convention .5
4 Mapping of the audio bitstream on to IEC 61937 .6
4.1 General .6
4.2 Windows Media Audio Professional burst-info .6
5 Format of WMA Professional data-burst .6
5.1 General .6
5.2 Pause data-burst.7
5.3 Audio data-bursts .7

Bibliography.13

Figure 1 – Windows Media Audio Professional type I data-burst .7
Figure 2 – Latency of WMA Professional type I decoding .8
Figure 3 – Windows Media Audio Professional type II data-burst .8
Figure 4 – Latency of WMA Professional type II decoding.9
Figure 5 – Windows Media Audio Professional type III data-burst .10
Figure 6 – Latency of WMA Professional type III decoding.10
Figure 7 – Windows Media Audio Professional type IV data-burst .11
Figure 8 – Latency of WMA Professional type IV decoding.11

Table 1 – Fields of burst-info .6
Table 2 – Repetition period of Pause data-bursts.7
Table 3 – Data-type-dependent when data-type = 18 and sub-type = 0 .7
Table 4 – Data-type-dependent when data-type = 18 and sub-type = 1 .9
Table 5 – Data-type-dependent when data-type = 18 and sub-type = 2 .10
Table 6 – Data-type-dependent when data-type = 18 and sub-type = 3 .11

61937-8 © IEC:2006(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958

Part-8: Non-linear PCM bitstreams according to
the Windows Media Audio (WMA) Professional format

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 61937-8 has been prepared by Technical Area 4: Digital system
interfaces, of IEC technical committee 100: Audio, video and multimedia systems and
equipment.
The text of this standard is based on the following documents:
CDV Report on voting
100/1018A/CDV 100/1095/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.

– 4 – 61937-8 © IEC:2006(E)
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.

61937-8 © IEC:2006(E) – 5 –
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958

Part-8: Non-linear PCM bitstreams according to
the Windows Media Audio (WMA) Professional format

1 Scope
This part of IEC 61937 specifies the method for the digital audio interface specified in
IEC 60958 to convey non-linear PCM bitstreams encoded in accordance with the WMA
Professional format.
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, Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 – Part 1: General
IEC 61937-2, Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 – Part 2: Burst-info
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms, definitions, abbreviations and
presentation convention apply.
3.1 Terms and definitions
3.1.1
latency
delay time of an external audio decoder to decode a WMA Professional data burst, defined as
the sum of two values of the receiving delay time and the decoding delay time
3.2 Abbreviations
ATSC Advanced Television Systems Committee
MPEG The Moving Pictures Expert Group, a joint committee of ISO and IEC
ITU-R International Telecommunication Union, Radio communication Bureau
WMA Windows Media Audio
3.3 Presentation convention
F872h
Value ‘F872’ in hexadecimal format

– 6 – 61937-8 © IEC:2006(E)
4 Mapping of the audio bitstream on to IEC 61937
4.1 General
The coding of the bitstream and data-burst shall be in accordance with IEC 61937-1.
4.2 Windows Media Audio Professional burst-info
The 16-bit burst-info contains information about the data that will be found in the data-burst in
accordance with Table 1.
Table 1 – Fields of burst-info
Reference Repetition period of
Bits of Pc Value Contents point R data-burst in
IEC 60958 frames
0 – 4 Data-type
0-17 According to IEC 61937-2
18 WMA Professional Subtype dependent Subtype dependent
19-31 According to IEC 61937-2
5 – 6 Data subtype
a
0 WMA Professional – Type I Bit 0 of Pa 2 048
1 WMA Professional – Type II Bit 0 of Pa 2 048
2 WMA Professional – Type III Bit 0 of Pa 1 024
3 WMA Professional – Type IV Bit 0 of Pa 512
7 – 15 According to IEC 61937-2

a
The reference point for a WMA Professional Type I stream is bit 0 of Pa of the first of a payload pair.

5 Format of WMA Professional data-burst
5.1 General
This clause specifies the audio data-burst for WMA Professional. Specific properties such as
reference points, repetition period, the method of filling stream gaps, and decoding latency
are specified for each data-type.
The decoding latency (or delay), indicated for the data-types, should be used by the
transmitter to schedule data-bursts as necessary to establish synchronization between picture
and decoded audio.
61937-8 © IEC:2006(E) – 7 –
5.2 Pause data-burst
Pause data-burst for WMA Professional Types I, II, III, and IV are given in Table 2.
Table 2 – Repetition period of Pause data-bursts
Repetition period of Pause data-burst
Data-ty
...