IEC 61937-10:2011

Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 10: Non-linear PCM bitstreams according to the MPEG-4 audio lossless coding (ALS) format

IEC 61937-10:2011 specifies the method for IEC 60958 to convey non-linear PCM bitstreams encoded in accordance with the MPEG-4 audio lossless coding (ALS) format.

Audionumérique - Interface pour les flux de bits audio à codage MIC non linéaire conformément à la CEI 60958 - Partie 10: Flux de bits à codage MIC non-linéaire selon le format MPEG-4 Audio sans perte (Audio Lossless Coding - ALS)

La CEI 61937-10:2011 spécifie la méthode de la CEI 60958 pour acheminer des flux de bits à codage MIC non linéaire suivant le format MPEG-4 Audio sans perte.

General Information

• Status: Published
• Publication Date: 19-Apr-2011
• ICS: 33.160.30 - Audio systems
• ICS: 35.240.99 - IT applications in other fields
• Technical Committee: TC 100 - Audio, video and multimedia systems and equipment
• Current Stage: DELPUB - Deleted Publication
• Start Date: 28-Jul-2017
• Completion Date: 26-Oct-2025

Relations

• Revised: IEC 61937-10:2017 - Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 10: Non-linear PCM bitstreams according to the MPEG-4 audio lossless coding (ALS) format
• Effective Date: 05-Sep-2023

Overview

IEC 61937-10:2011 is an international standard published by the International Electrotechnical Commission (IEC) that defines the interface method to convey non-linear PCM (Pulse Code Modulation) audio bitstreams using IEC 60958. Specifically, this standard focuses on bitstreams encoded using the MPEG-4 audio lossless coding (ALS) format. It provides detailed guidelines for transmitting these high-fidelity, lossless audio streams over digital audio interfaces compliant with IEC 60958.

By standardizing this process, IEC 61937-10:2011 ensures interoperability and reliable transmission of MPEG-4 ALS encoded audio between digital audio equipment, facilitating seamless integration in professional audio and multimedia systems.

Key Topics

• Scope and Purpose
  IEC 61937-10 specifies how IEC 60958 interfaces carry non-linear PCM bitstreams encoded according to the MPEG-4 ALS format. This enables digital transport of high-resolution, lossless audio data in a consistent and standardized manner.

• Mapping of Audio Bitstreams
  The standard details the mapping of MPEG-4 ALS bitstreams onto the IEC 61937 digital audio interface. It defines data-type identifiers, burst-info fields, and sub-data types specifically for ALS bitstreams to ensure correct recognition and decoding.

• Audio Data-Burst Format
  MPEG-4 ALS audio data is transmitted in bursts, each preceded by a burst-preamble and containing an ALSSpecificConfig header followed by ALS random access units. Each data-burst is self-contained with its own configuration, enabling efficient decoding and synchronization.

• Latency and Synchronization
  Decoding latency-sum of receiving and decoding delay-is defined to help maintain synchronization between audio and video streams. The standard covers handling of latency to avoid timing mismatches in multimedia applications.

• Burst Payload and Repetition
  Specifications include the structure and size of the burst payload, repetition periods related to IEC 60958 frame rates, and management of stuffing bits to keep data stream alignment.

• Terms and Definitions
  The document clarifies critical technical terms like sub-data-type, length code, als_id, samp_freq, and others to support precise communication among engineers and implementers.

Applications

IEC 61937-10:2011 is essential in various practical scenarios involving digital audio transmission where lossless quality and interoperability are critical:

• Professional Audio Equipment
  Studios and broadcast environments benefit from standardized transmission of high-resolution, lossless audio via digital audio interfaces.

• Consumer Electronics
  High-end audio players, home theater systems, and digital receivers use these standards to support superior audio formats seamlessly.

• Multimedia Systems
  Integration of audio with video in digital television, streaming services, and multimedia authoring tools relies on standardized audio transport to maintain audiovisual synchronization and quality.

• Digital Audio Workstations (DAWs)
  For accurate recording, editing, and playback without quality loss, digital audio workstations employ such standardized interfaces supporting MPEG-4 ALS streams.

• Interoperability Testing and Certification
  Equipment manufacturers use IEC 61937-10 compliance as a benchmark to ensure their products work reliably with other devices exchanging MPEG-4 ALS audio bitstreams.

Related Standards

To fully leverage IEC 61937-10:2011, several related IEC and ISO/IEC standards are relevant:

• IEC 60958 (All Parts)
  The foundational standard for digital audio interfaces that IEC 61937-10 applies to and extends for non-linear PCM bitstreams.

• IEC 61937 (Series)
  Provides the general framework and additional parts defining burst-info, data-type fields, and methods for various audio codecs beyond MPEG-4 ALS.

• ISO/IEC 14496-3 (Part 3 of MPEG-4)
  Defines audio coding including the MPEG-4 ALS format itself, which IEC 61937-10 specifically maps for digital interface transmission.

• IEC 61937-1 and IEC 61937-2
  These parts establish general rules and burst-info structure critical for interpreting and packaging MPEG-4 ALS bitstreams.

Conclusion

IEC 61937-10:2011 is a vital technical standard that enables the accurate and efficient transmission of MPEG-4 audio lossless coding (ALS) bitstreams over IEC 60958 digital audio interfaces. By adhering to this international standard, manufacturers and integrators in the audio, broadcasting, and multimedia industries can ensure high-quality, synchronized delivery of lossless PCM audio, fostering seamless interoperability and advancing digital audio technology worldwide.

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Keywords: IEC 61937-10, IEC 60958, MPEG-4 ALS, MPEG-4 audio lossless coding, digital audio interface, non-linear PCM, audio bitstream transmission, lossless audio coding, digital audio standard, audio synchronization, professional audio, multimedia systems.

Standards Content (Sample)

IEC 61937-10 ®
Edition 1.0 2011-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 –
Part 10: Non-linear PCM bitstreams according to the MPEG-4 audio lossless
coding (ALS) format
Audionumérique – Interface pour les flux de bits audio à codage MIC non
linéaire conformément à la CEI 60958 –
Partie 10: Flux de bits à codage MIC non-linéaire selon le format MPEG-4 Audio
sans perte (Audio Lossless Coding – ALS)

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IEC 61937-10 ®
Edition 1.0 2011-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Digital audio – Interface for non-linear PCM encoded audio bitstreams applying
IEC 60958 –
Part 10: Non-linear PCM bitstreams according to the MPEG-4 audio lossless
coding (ALS) format
Audionumérique – Interface pour les flux de bits audio à codage MIC non
linéaire conformément à la CEI 60958 –
Partie 10: Flux de bits à codage MIC non-linéaire selon le format MPEG-4 Audio
sans perte (Audio Lossless Coding – ALS)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX P
ICS 33.160.30; 35.240.99 ISBN 978-2-88912-454-1

– 2 – 61937-10  IEC:2011
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, abbreviations and conventions . 5
3.1 Terms and definitions . 5
3.2 Abbreviations . 6
3.3 Presentation convention . 6
4 Mapping of the audio bitstream onto IEC 61937 . 6
4.1 General . 6
4.2 MPEG-4 ALS burst-info . 6
5 Format of MPEG-4 ALS data-bursts . 7
5.1 General . 7
5.2 Audio data-bursts . 7
5.2.1 Data-burst for MPEG-4 ALS . 7
5.2.2 Latency of MPEG-4 ALS decoding . 9
Annex A (informative) Effect of repetition period of data-burst and IEC 60958 frame
rate on frame period for the MPEG-4 ALS bitstreams . 11
Annex B (normative) Burst payload format for MPEG-4 ALS . 12
Annex C (normative) Values for ALSSpecificConfig in the MPEG-4 ALS burst payload
format . 13
Bibliography . 15

Figure 1 – MPEG-4 ALS data-burst . 8
Figure 2 – Latency of MPEG-4 ALS decoding . 9
Figure 3 – The MPEG-4 ALS burst-payload. 9
Figure B.1 – MPEG-4 ALS burst-payload . 12

Table 1 – Fields of burst-info (data-type=23, sub-data-type=0) . 7
Table 2 – Sample rate and number of channels of MPEG-4 ALS encoded audio,
multiplier, and IEC 60958 frame rate . 9
Table A.1 – MPEG-4 ALS payload and frame repetition: some examples . 11
Table C.1 – Recommended values for the ALSSpecificConfig in the MPEG-4 ALS
burst-payload . 13

61937-10  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 10: Non-linear PCM bitstreams according
to the MPEG-4 audio lossless coding (ALS) format

FOREWORD
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61937-10 has been prepared by technical area 4: Digital system
interfaces and protocols, 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
100/1733/CDV 100/1808/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 – 61937-10  IEC:2011
A list of all the parts in the IEC 61937 series, published 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 stability 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.
61937-10  IEC:2011 – 5 –
DIGITAL AUDIO –
INTERFACE FOR NON-LINEAR PCM ENCODED
AUDIO BITSTREAMS APPLYING IEC 60958 –

Part 10: Non-linear PCM bitstreams according
to the MPEG-4 audio lossless coding (ALS) format

1 Scope
This part of IEC 61937 specifies the method for IEC 60958 to convey non-linear PCM
bitstreams encoded in accordance with the MPEG-4 audio lossless coding (ALS) 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 (all parts), Digital audio – Interface for non-linear PCM encoded audio bitstreams
applying IEC 60958
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
ISO/IEC 14496-3:2009, Information technology – Coding of audio-visual objects – Part 3:
Audio
Amendment 2:2010, ALS Simple Profile and Transport of SAOC
3 Terms, definitions, abbreviations and conventions
For the purposes of this document, the following terms and definitions, abbreviations and
presentation conventions apply.
3.1 Terms and definitions
3.1.1
sub data-type
reference to the type of payload of the data-burst defined for use with the specified data-type
3.1.2
latency
delay time of an external audio decoder to decode a MPEG-4 ALS data-burst, defined as the
sum of the receiving delay time and the decoding delay time
3.1.2
length code
code indicating the length of the data-burst-payload in 8-byte units according to this standard

– 6 – 61937-10  IEC:2011
3.1.4
als_id
ALS identifier in ALSSpecificConfig
3.1.5
samp_freq
sampling frequency of the audio samples contained in the MPEG-4 ALS burst payload
3.1.6
samples
number of audio samples per channel contained in the MPEG-4 ALS burst payload
NOTE In contrast to the ALS specification, each data-burst provides its own ALSSpecificConfig. Thus the
'samples' value refers to the total number of samples (per channel) of that data-burst.
3.1.7
channels
number of channels-1, 'channels', contained in the MPEG-4 ALS burst payload
3.1.8
resolution
bit depth of the audio samples contained in the MPEG-4 ALS burst payload
3.1.9
aux_size
size of the auxiliary data field in bytes for MPEG-4 ALS
3.1.10
aux_data
auxiliary data contained in the MPEG-4 ALS burst payload
NOTE Not required for decoding audio samples.
3.2 Abbreviations
ALS Audio Lossless Coding
PCM Pulse-Code Modulation
3.3 Presentation convention
01 Value “01” in binary format
4 Mapping of the audio bitstream onto IEC 61937
4.1 General
The coding of the bitstream and data-burst is in accordance with the IEC 61937 series of
standards.
4.2 MPEG-4 ALS 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.
61937-10  IEC:2011 – 7 –
Table 1 – Fields of burst-info (data-type=23, sub-data-type=0)
Bits of Value Contents Reference Repetition period of
Pc point R data-burst in
IEC 60958 frames
0 to 4 data-type
0-22 In accordance with IEC 61937-2
23 MPEG-4 ALS or other applications according to Bit 0 of Pa See 5.2.1
IEC 61937-2, depending on sub-data-type
24-31 In accordance with IEC 61937-2
5, 6 sub data-type
0 MPEG-4 ALS See 5.2.1
1-3 In accordance with IEC 61937-2
7 0 Error-flag indicating a valid burst-payload
1 Burst may contain errors
8 to 12 Data-type and sub-data-type dependent
information for MPEG-4 ALS
8 Multiplier
0 [IEC 60958 frame rate] = audio sampling rate × 2
1 [IEC 60958 frame rate] = audio sampling rate × 8

9 to 12 0000 No indication
0001 ALS Simple Profile Level 1
0010- Reserved for future Profile or Level
13 to 15 In accordance with IEC 61937-1 and
IEC 61937-2.
5 Format of MPEG-4 ALS data-bursts
5.1 General
This clause specifies the audio data-burst MPEG-4 ALS. 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 synchronisation between video
and decoded audio.
5.2 Audio data-bursts
5.2.1 Data-burst for MPEG-4 ALS
Figure 1 shows the detailed description of the MPEG-4 ALS data-burst. The stream of the
data-bursts for MPEG-4 ALS consists of sequences of MPEG-4 ALS bitstreams. The data-
type of a MPEG-4 ALS data-burst is 23. The sub data-type is 0. The data-burst is headed with
a burst-preamble, followed by the burst-payload, and stuffed with stuffing bits. The burst-
payload of each data-burst of MPEG-4 ALS data shall contain an ALSSpecificConfig header,
and one or more ALS random access units. Each data-burst constitutes a self-contained ALS
bitstream, whose number of samples (per channel) is given in the field 'samples' of (the
corresponding) ALSSpecificConfig. The units of length-code (burst_length) shall be in 8-bytes.

– 8 – 61937-10  IEC:2011
Note that if the actual data size of the data-burst is not a multiple of 8 bytes, 1 to 7 stuffing
bytes are included in the burst_length.
The number of samples for each encoded channel contained in the data-burst are indicated in
the encoded ALS bitstream. The length of the MPEG-4 ALS data-burst depends on the
encoded bit rate (which determines the MPEG-4 ALS frame length). For details, see Annex B.
The reference to the specification for the MPEG-4 ALS bitstream, representing the number of
samples of encoded audio per frame, may be found in ISO/IEC 14496-3, subpart 11.

MPEG- 4 ALS  MPEG- 4 ALS
Pa  Pb  Pc  Pd  Pa  Pb  Pc  Pd
burst-payload  burst-payload
Bit 0 of Pa
Bit 0 of Pa
Stuffing
MPEG-4 ALS frame MPEG-4 ALS frame

-
Regular rate of the MPEG 4 ALS  frames

Repetition period of the burst

IEC  708/11
Figure 1 – MPEG-4 ALS data-burst
The regular rate of the MPEG-4 ALS frames and the repetition period of the data burst can be
calculated as
'[samples] × [IEC 60958 frame rate]/[sampling frequency of the encoded audio samples
(samp_freq)]'.
The value of the 'samples' field is stored in the 9th to 12th bytes of the MPEG-4 ALS burst-
payload. The value represents the number of samples contained in the MPEG-4 ALS burst-
payload. The IEC 60958 frame rate is defined by the audio sampling rate and a value of the
multiplier (see Table.2).
The reference point of a MPEG-4 ALS data-burst is bit 0 of Pa and occurs exactly once every
predefined number of IEC 60958 frames. The data-burst containing MPEG-4 ALS frames shall
occur at a regular rate, with the reference point of each MPEG-4 ALS data-burst beginning
after the number of IEC 60958 frames in the previous MPEG-4 ALS data-burst from the
reference point of the preceding MPEG-4 ALS data-burst (of the same bit-stream-number).
It is recommended that pause data-bursts be used to fill stream gaps in the MPEG-4 ALS bit
stream as described in the IEC 61937-1, and that pause data-bursts be transmitted with a
repetition period of 32 IEC 60958 frames, except when other repetition periods are necessary
to fill the precise stream gap length (which may not be a multiple of 32 IEC 60958 frames), or
to meet the requirement on burst spacing (see IEC 61937-1).
When a stream gap in an MPEG-4 ALS stream is filled by a sequence of pause data-bursts,
the Pa of the first pause data-burst shall be located after a number of sampling periods
represented by the 'samples' field of the ALSSpecificConfig header in the previous MEG-4
ALS data-burst from the Pa of the previous MPEG-4 ALS frame. It is also recommended that
the sequence(s) of pause data-bursts that fill the stream gap should continue from this point
up to (as close as possible, considering the 32 IEC 60958 frame length of the pause data-
burst) the Pa of the first MPEG-4 ALS data-burst that follows the stream gap. The MPEG-4
ALS decoder can detect the number of decoded PCM samples by using the value set in the
'samples' field of ALSSpecificConfig.

61937-10  IEC:2011 – 9 –
Table 2 shows the relation between the sample rate of MPEG-4 ALS encoded audio and the
IEC 60958 frame rate used to deliver MPEG-4 ALS encoded audio via the IEC 61937-10
interface.
Table 2 – Sample rate and number of channels of MPEG-4 ALS encoded audio,
multiplier, and IEC 60958 frame rate
Audio sampling rate Number of Multiplier IEC 60958 frame rate
channels
kHz kHz
1, 2 0 (×2) 96
3 to 8 1 (×8) 384
1, 2 0 (×2) 192
3 to 8 1 (×8) 768
1, 2 0 (×2) 384
3 to 8 1 (×8) 1 536
1, 2 0 (×2) 88,2
44,1
3 to 8 1 (×8) 352,8
5.2.2 Latency of MPEG-4 ALS decoding
The latency of an external audio decoder to decode MPEG-4 ALS is defined as the sum of the
receiving delay time and the decoding delay time as shown in Figure 2.

MPEG- 4  ALS     MPEG- 4  ALS
Pa  Pb  Pc  Pd  Pa  Pb  Pc  Pd
bur st- payload  bur st -p ayload
Bit 0 of Pa
Bit 0 of Pa
MPEG- 4 ALS frame  Stuffing
MPEG- 4 ALS frame
Repetition period of the burst

Decoding delay
Receiving delay
Latency of MPEG-4 ALS decoder
IEC  709/11
Figure 2 – Latency of MPEG-4 ALS decoding

MPEG- 4  ALS
Pa  Pb  Pc  Pd
Stuffing
bur st- payload
Bit 0 of Pa
MPEG- 4  ALS     MPEG-4 ALS Random access unit
Nd
ALSSpecificConfi g (a frame or frames)
MPEG - 4 ALS fram e
IEC  710/11
Figure 3 – The MPEG-4 ALS burst-payload

– 10 – 61937-10  IEC:2011
The receiving delay time to receive a whole data-burst is calculated by using the length of the
burst-payload, Nd, which is shown in Figure 3. The length of preamble is 8 bytes. Since an
IEC 60958 frame can contain 4 bytes, the receiving delay of an MPEG-4 ALS data-burst
should be as follows:
Receiving delay = (Nd + 8 bytes)/([IEC 60958 frame rate] × 4 bytes)
The maximum receiving delay time is related to the number of samples contained in the data-
th
burst and the IEC 60958 frame rate. The number of samples, 'samples', is stored in the 9 to
th th th
12 bytes of the ALSSpecificConfig header of the MPEG-4 ALS burst-payload (13 to 16
bytes of the MPEG-4 ALS burst-payload) as shown in Figure 3. The maximum decoding delay
time can be regarded as being the same as the maximum receiving delay time.
Note that the encoded size never exceeds the rate given by the IEC 60958 frame rate in
theory except when the Aux data in burst is too large. The Aux size shall be small enough to
ensure that the total size of the burst complies with following formula:
Pd <= ((([samples]/[samp_freq]) × [IEC 60958 frame rate] × 4 bytes) – 8 bytes)/8
EXAMPLE The maximum size of the MPEG-4 ALS burst-payload shall be equal to or less
than the size calculated by the frame repetition period and the IEC 60958 frame rate. When
the values of 'samp_freq', 'samples', 'channels', and 'resolution' are 48 000, 2 048, 1, and 1
respectively, the sampling rate of the audio signal is 48 kHz, the number of samples
contained in the MPEG-4 ALS burst-payload is 2 048 samples, the number of channels is 2
(='channels'+1), and the number of bits per an audio sample is 16 bits. With these values, the
IEC 60958 frame rate is 96 kHz as shown in Table 2. Though the receiving delay time varies
depending on the compressed size of the MPEG-4 ALS burst-payload, the maximum receiving
delay time can be calculated by using 'samples' and 'samp_freq'. In this example case, it
should be 42,67 ms (2 048/48 000 = 0,042 67). The maximum decoding delay time should be
42,67 ms because it can be regarded as being the same as the maximum receiving delay time.
The total latency of MPEG-4 ALS decoding is approximately 85,34 ms.

61937-10  IEC:2011 – 11 –
Annex A
(informative)
Effect of repetition period of data-burst and IEC 60958 frame rate
on frame period for the MPEG-4 ALS bitstreams

Table A.1 shows IEC 60958 frame rates, their repetition period and their frame period in
milliseconds.
Table A.1 – MPEG-4 ALS payload and frame repetition: some examples
Sampling Frame IEC 60958 frame rate Frame period
rate repetition
Fs ms
period
44,1 kHz 1 024 88,2 kHz for 2 ch 23,22
352,8 kHz for 3 to 8 ch
2 048 46,44
4 096 92,88
8 192 185,76
48 kHz 1 024 96 kHz for 2 ch 21,33
2 048 384 kHz for 3 to 8 ch 42,66

4 096 85,32
8 192 170,64
96 kHz 2 048 192 kHz for 2 ch 21,33
4 096 768 kHz for 3 to 8 ch 42,66

8 192 85,32
16 384 170,64
192 kHz 4 096 384 kHz for 2 ch 21,33
1 536 kHz for 3 to 8 ch
8 192 42,36
16 384 85,32
ch = channels
– 12 – 61937-10  IEC:2011
Annex B
(normative)
Burst payload format for MPEG-4 ALS

Figure B.1 shows the detailed description of the MPEG-4 ALS burst-payload.
The MPEG-4 ALS burst-payload contains an ALSSpecificConfig and one or more random
access units. The ALSSpecificConfig is defined in the specification of the ISO/IEC 14496-3.

MPEG -4  ALS
Pa  Pb  Pc  Pd
Stuffing
bur st- payload
Bit 0 of Pa
MPEG - 4 ALS     MPEG-4 ALS Random access unit
Nd
ALSSpecificConfi g (a frame or frames)
MPEG- 4 ALS fram e
IEC  711/11
Figure B.1 – MPEG-4 ALS burst-payload
The first 4 bytes of the MPEG-4 ALS burst-payload should be the 'Nd'. The value indicates
size of the MPEG-4 ALS burst-payload (including Nd) in bytes.
Following 4 bytes of the MPEG-4 ALS burst-payload should be the 'als_id'. The values of the
first 3 bytes in the 'als_id' should be 'A', 'L', 'S'.
The sampling frequency of the samples, 'samp_freq', contained in the MPEG-4 ALS burst
payload can be detected in the 4 bytes following 'als_id'.
The number of samples per channel, 'samples', contained in the MPEG-4 ALS burst payload
can be detected in the following 4 bytes after the 'samp_freq'.
The number of channels, 'channels', contained in the MPEG-4 ALS burst payload can be
detected in the 2 bytes following 'samples'.
The maximum size of the MPEG-4 ALS burst-payload shall be equal to or less than the size
calculated by the frame repetition period and the IEC 60958 frame rate.
Repetition period of the data-burst = 'samples' × IEC 60958 frame rate/'samp_freq'.
IEC 60958 frame rate of the MPEG-4 ALS data-burst is defined by 'samp_freq' and 'channels'.

61937-10  IEC:2011 – 13 –
Annex C
(normative)
Values for ALSSpecificConfig in the MPEG-4 ALS burst
payload format
Table C.1 shows the recommended values for the ALSSpecificConfig in the MPEG-4 ALS
burst-payload. The ALSSpecificConfig is defined in the specification of the ISO/IEC 14409-3.
Table C.1 – Recommended values for the ALSSpecificConfig
in the MPEG-4 ALS burst-payload
Field #Bits Recommended values Description
als_id 32 0x414C5300 (Hex) "ALS\0"
samp_freq 32 Up to 192 kHz For ALS simple profile level 1,
samp_freq shall be any of 44 100
or 48 000.
samples 32 Number of samples (per Number of samples contained in a
channel) MPEG-4 ALS burst-payload.
Examples of preferred values:
The value 0xFFFFFFFF (HEX)
1 024, 2 048, 4 096, 8 192,
is not allowed for samples in
10 240, 20 480, 30 720.
this standard.
channels 16 0=mono Up to 8 channels.
1=stereo The actual number of channels
contained in the ALS bitstream can
:
be calculated by 'channels+1'.
7 = 8 channels
For ALS simple profile level 1,
channels value shall be 0=mono or
n-1=n channels
1=stereo.
(other values are reserved)
file_type 3 000 = unknown / raw file The value of the file_type should
be 0 (raw file).
resolution 3 000 = 8-bit For ALS simple profile level 1,
resolution value shall be
001 = 16-bit
000=8-bit or 001=16-bit.
010 = 24-bit
(other values are reserved)
floating 1 0 = integer
msb_first 1 0 = least significant byte first If resolution = 0 (8-bit data),
msb_first = 0 indicates unsigned
1 = most significant byte first
data (0…255), while msb_first = 1
indicates signed data (−128…127).
frame_length 16 Any For ALS simple profile level 1,
frame_length value shall be up to
4 096.
random_access 8 1 or larger value To be set to at least every x
samples defined in repetition
period of data-burst in IEC 60958
frames.
ra_flag 2 00: not stored
Indicates where the size of random
access units (ra_unit_size) is stored.

adapt_order 1 Any
coef_table 2 Any
long_term_prediction 1 Any
max_order 10 Any For ALS simple profile level 1,
max_order value shall be up to 14.

– 14 – 61937-10  IEC:2011
Field #Bits Recommended values Description
block_switching 2 Any For ALS simple profile level 1,
block_switching value shall be up
to 3.
bgmc_mode 1 Any For ALS simple profile level 1,
bgmc_mode value shall be 0.
sb_part 1 Any
joint_stereo 1 Any
mc_coding 1 Any For ALS simple profile level 1, the
maximum MCC stage shall be 1
when mc_coding = 1.
chan_config 1 0: No chan_config_info field is
present
chan_sort 1 0: off
crc_enabled 1 0: No CRC field is present.
1: A CRC field is present
...