IEC 61937-7:2002

INTERNATIONAL IEC
STANDARD
61937-7
First edition
2002-05
Digital audio – Interface for non-linear PCM
encoded audio bitstreams applying IEC 60958 –
Part 7:
Non-linear PCM bitstreams according
to the ATRAC and ATRAC 2/3 formats

Reference number
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INTERNATIONAL IEC
STANDARD
61937-7
First edition
2002-05
Digital audio – Interface for non-linear PCM
encoded audio bitstreams applying IEC 60958 –
Part 7:
Non-linear PCM bitstreams according
to the ATRAC and ATRAC 2/3 formats

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– 2 – 61937-7 © IEC:2002(E)
CONTENTS
FOREWORD.3

INTRODUCTION.4

1 Scope.5

2 Normative references .5

3 Terms, definitions and abbreviations .5

3.1 Definitions .5

3.2 Abbreviations .5

4 Mapping of the audio bitstream on to IEC 61937.6
4.1 General .6
4.2 ATRAC and ATRAC2/3 burst-info .6
5 Format of ATRAC and ATRAC2/3 data-bursts.6
5.1 General .6
5.2 Audio data-bursts .6
5.2.1 The data ATRAC .6
5.2.2 Latency of ATRAC decoding.8
5.2.3 The data ATRAC2/3.8
5.2.4 Latency of ATRAC2/3 decoding .9
Bibliography.11
Figure 1 – ATRAC data-burst.7
Figure 2 – Latency of ATRAC decoding .8
Figure 3 – ATRAC2/3 data-burst .8
Figure 4 – Latency of ATRAC2/3 decoding.9
Table 1 – Fields of burst-info .6
Table 2 – Data-type-dependent information for data-type ATRAC .7
Table 3 – Data-type dependent information for data-type ATRAC2/3.9

61937-7 © IEC:2002(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
DIGITAL AUDIO – INTERFACE FOR NON-LINEAR PCM ENCODED

AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 7: Non-linear PCM bitstreams according to

the ATRAC and ATRAC2/3 formats

FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61937-7 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:
FDIS Report on voting
100/457/FDIS 100/492/RVD
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 committee has decided that the contents of this publication will remain unchanged until 2005.
At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 4 – 61937-7 © IEC:2002(E)
INTRODUCTION
The format of the IEC 60958 interface consists of a sequence of IEC 60958 sub-frames. Each

IEC 60958 sub-frame 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. IEC 61937 defines the data-bursts of the

data-types NULL, AC-3, PAUSE, MPEG-1, AC-3, MPEG-1, Layer-2 or Layer-3, or MPEG-2

without extension, MPEG-2 with extension, MPEG-2, Layer-1 Low sampling frequency and

MPEG-2, Layer-2 or Layer-3 Low sampling frequency.

This part specifies the data-types ATRAC and ATRAC2/3.

61937-7 © IEC:2002(E) – 5 –
DIGITAL AUDIO – INTERFACE FOR NON-LINEAR PCM ENCODED

AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 7: Non-linear PCM bitstreams according to

the ATRAC and ATRAC2/3 formats

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 ATRAC and
ATRAC2/3 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 60958-1, Digital audio interface – Part 1: General
IEC 60958-3, Digital audio interface – Part 3: Consumer applications
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 information
3 Terms, definitions and abbreviations
3.1 Definitions
For the purpose of this standard, the definitions given in IEC 61937-1 and IEC 61937-2, as
well as the following apply.
3.1.1
latency
delay time of an external audio decoder to decode a ATRAC and ATRAC2/3 data-burst,
defined as the sum of two values of the receiving delay time and the decoding delay time
3.2 Abbreviations
ATRAC Adaptive TRansform Acoustic Coding
ATRAC2 Adaptive TRansform Acoustic Coding 2
ATRAC3 Adaptive TRansform Acoustic Coding 3
ATRAC2/3 ATRAC2 and/or ATRAC3
To be published.
– 6 – 61937-7 © IEC:2002(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.

4.2 ATRAC and ATRAC2/3 burst-info

This 16-bit burst-info shall contain data-burst information structured in accordance with

table 1.
Table 1 – Fields of burst-info
Repetition period of
Reference
Bits of Pc Value Contents data-burst in IEC 60958
point R
frames
0-4 data-type
0-13 in accordance with IEC 61937
14 ATRAC bit 0 of Pa 512
15 ATRAC2/3 bit 0 of Pa 1024
16-31 reserved
5-15 in accordance with IEC 61937
5 Format of ATRAC and ATRAC2/3 data-bursts
5.1 General
This clause specifies the audio data-bursts ATRAC and ATRAC2/3. Specific properties such
as reference points, repetition period, the method of filling stream gaps, and decoding latency
are specified for each data-type of ATRAC and ATRAC2/3.
The decoding latency (or delay), indicated for the data-types, shall be used by the transmitter
to schedule data-bursts as necessary to establish synchronization between the picture and
the decoded audio.
NOTE For both ATRAC and ATRAC2/3 formats, the recommended repetition value period of pause data-bursts
is 32 IEC 60958 frames.
5.2 Audio data-bursts
5.2.1 The data ATRAC
The ATRAC bitstream consists of sequences of ATRAC frames. The data-type of an ATRAC
data-burst is 0Eh. The data-burst is headed with a burst-preamble, followed by the burst-
payload, and is stuffed with stuffing bits (see figure 1). The burst-payload of each data-burst
of ATRAC data shall contain one complete ATRAC frame, and represents 512 samples for
each encoded channel. The length of the ATRAC data-burst depends on the encoded bit rate
(which determines the ATRAC-frame length).
NOTE The reference to the specification for the ATRAC bitstream, representing 512 samples of encoded audio
per frame, may be found in the bibliography.

61937-7 © IEC:2002(E) – 7 –
Pa Pb Pc Pd ATRAC Pa Pb Pc Pd ATRAC

Burst_payload Burst_payload
Bit 0 of Pa
Bit 0 of Pa
Stuffing
ATRAC frame
ATRAC frame
Regular rate of ATRAC frames
Repetition period of the burst

IEC  1089/02
Figure 1 – ATRAC data-burst
The data-type-dependent information for ATRAC is given in table 2.
Table 2 – Data-type-dependent information for data-type ATRAC
Bits of Pc Data type dependent,
bit number Contents
LSB.MSB LSB.MSB
8-12 00h – 1Fh reserved, shall be set to ‘0’
The reference point of an ATRAC data-burst is bit 0 of Pa and shall occur exactly once every
512 sampling periods. The data-burst containing ATRAC frames shall occur at a regular rate,
with the reference point of each ATRAC data-burst beginning 512 IEC 60958 frames after the
reference point of the preceding ATRAC data-burst (of the same
...