IEC 61883-6:2002

Consumer audio/video equipment - Digital interface - Part 6: Audio and music data transmission protocol

General Information

• Status: Published
• Publication Date: 13-Oct-2002
• ICS: 33.160.01 - Audio, video and audiovisual systems in general
• ICS: 35.200 - Interface and interconnection equipment
• Technical Committee: TC 100 - Audio, video and multimedia systems and equipment
• Current Stage: DELPUB - Deleted Publication
• Start Date: 28-Oct-2005
• Completion Date: 26-Oct-2025

Relations

• Replaces: IEC PAS 61883-6:1998 - Consumer audio/video equipment - Digital interface - Part 6: Audio and music data transmission protocol
• Effective Date: 05-Sep-2023
• Revised: IEC 61883-6:2005 - Consumer audio/video equipment - Digital interface - Part 6: Audio and music data transmission protocol
• Effective Date: 05-Sep-2023

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD
61883-6
First edition
2002-10
Consumer audio/video equipment –
Digital interface –
Part 6:
Audio and music data transmission protocol
Matériel audio/vidéo grand public –
Interface numérique –
Partie 6:
Protocole de transmission de données
audio et musicales
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 (http://www.iec.ch/searchpub/cur_fut.htm)
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 (http://www.iec.ch/online_news/
justpub/jp_entry.htm) 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
61883-6
First edition
2002-10
Consumer audio/video equipment –
Digital interface –
Part 6:
Audio and music data transmission protocol
Matériel audio/vidéo grand public –
Interface numérique –
Partie 6:
Protocole de transmission de données
audio et musicales
 IEC 2002  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
U
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 61883-6  IEC:2002(E)
CONTENTS
FOREWORD . 4

1 Scope . 6

2 Normative references. 6

3 Terms and definitions . 6

4 Transport requirements. 7

4.1 Arbitrated short bus reset . 7
4.2 Bit, byte, and quadlet ordering . 7
5 Packet header for audio and music data . 7
5.1 Isochronous packet header format . 7
5.2 CIP header format . 8
6 Packetization . 8
6.1 Packet transmission method . 8
6.2 Transmission of timing information. 9
6.3 Time stamp processing. 9
6.4 Transmission control.10
7 Event Types.11
7.1 General .11
7.2 AM824 Data.14
7.3 32-bit floating point data .17
7.4 24-bit x 4 Audio Pack.17
8 Subformat.18
8.1 Basic format .18
8.2 Special Format .20
Annex A (informative) Blocking transmission method .21
Annex B (informative) Synchronization Issues.23
Annex C (informative) Catching up in Non-Blocking Transmission method .25
Bibliography.26
Figure 1 – Isochronous packet header. 7
Figure 2 – Common isochronous packet (CIP) format. 8
Figure 3 – Non-blocking transmission method .10
Figure 4 – Transmission parameters .11
Figure 5 – Cluster events .12
Figure 6 – Pack and cluster events .13
Figure 7 – Pack event with 24-bit event sequence.13
Figure 8 – Generic AM824 format.14
Figure 9 – IEC 60958 conformant data format .15
Figure 10 – Raw audio data format.16
Figure 11 – Alignment of 20-bit data in 24-bit field .16
Figure 12 – MIDI conformant data format .16
Figure 13 – "No Data" format .17

61883-6  IEC:2002(E) – 3 –
Figure 14 – 32-bit floating point data format .17

Figure 15 – 24-bit * 4 audio pack format.18

Figure 16 – Generic FDF definition.19

Figure 17 – FDF code for NO-DATA packet.20

Figure A.1 – Blocking transmission method .21

Table 1 – Isochronous packet header fields . 8

Table 2 – CIP fields. 8

Table 3 – Generic AM824 format.15
Table 4 – IEC 60958 conformant data format .15
Table 5 – Raw audio data format.16
Table 6 – MIDI conformant data format .17
Table 7 – Subformat and FDF allocations.18
Table 8 – DBS for AM824 and 32-bit floating point data .19
Table 9 – DBS for 24-bit x 4 audio pack .19
Table 10 – Event type (EVT) code definition.19
Table 11 – SFC (Nominal Sampling Frequency Code) definition.19
Table A.1 – TRANSFER_DELAY for differing values of STF.22

– 4 – 61883-6  IEC:2002(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

___________
CONSUMER AUDIO/VIDEO EQUIPMENT –

DIGITAL INTERFACE –
Part 6: Audio and music data transmission protocol

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 61883-6 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
100/526/FDIS 100/569/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.
This publication replaces IEC/PAS 61883-6:1998
The committee has decided that the contents of this publication will remain unchanged until
31 October 2005. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61883-6  IEC:2002(E) – 5 –
IEC 61883 consists of the following parts, under the general title Consumer audio/video

equipment – Digital interface
• Part 1: General
• Part 2: SD-DVCR data transmission

• Part 3: HD-DVCR data transmission

• Part 4: MPEG2-TS data transmission

• Part 5: SDL-DVCR data transmission

• Part 6: Audio and music data transmission protocol

• Part 7: Transmission of Rec. ITU-R BO.1294 System B Transport 1.0

– 6 – 61883-6  IEC:2002(E)
CONSUMER AUDIO/VIDEO EQUIPMENT –

DIGITAL INTERFACE –
Part 6: Audio and music data transmission protocol

1 Scope
This part of IEC 61883 describes a protocol for the transmission of audio and music data
employing IEEE 1394, and specifies essential requirements for the application of the protocol.
This protocol can be applied to all modules or devices which have any kind of audio and/or
music data processing, generation and conversion function blocks. This standard deals only
with the transmission of audio and music data; the control, status and machine readable
description of these modules or devices should be defined outside of this document according
to each application area.
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 60958-1:1999, Digital audio interface – Part 1: General
IEC 60958-3:1999, Digital audio interface – Part 3: Consumer applications
IEC 60958-4:1999, Digital audio interface – Part 4: Professional applications
IEC 61883-1, Consumer audio/video equipment – Digital interface – Part 1: General
IEEE Std 754:1985, Standard for Binary Floating-Point Arithmetic
IEEE Std 1394:1995, Standard for a High Performance Serial Bus – Firewire
IEEE Std 1394A:2000, Standard for a High Performance Serial Bus – Amendment 1
3 Terms and definitions
For the purpose of this part of IEC 61883, the terms and definitions given in IEC 61883-1
apply, together with the following.

3.1.1
32-bit floating-point data
data type which is defined in IEEE 754:1985, Standard for Binary Floating-Point Arithmetic.
3.1.2
A/M Protocol
protocol for the transmission of audio and music data over IEEE 1394
3.1.3
MIDI
Musical Instrument Digital Interface
NOTE The Complete MIDI 1.0 Detailed Specification, Version 96.1, March 1996a, is a specification for the
interconnection of digital music processing devices (e.g. keyboards, signal processors) and computers.

61883-6  IEC:2002(E) – 7 –
3.1.4
music data
data generally used for controlling a tone generator

NOTE The data defined in the MIDI specification, which may be called MIDI data, are an example of music data.

3.1.5
reserved
keyword used to describe objects - bit, byte, quadlet, octet, and field - or the code values

assigned to these objects; the object or the code value is set aside for future standardization

by the IEC
3.1.6
stream
uni-directional data transmission
3.1.7
time stamp
quantized timing in which an event occurs based on a reference clock
NOTE The reference clock is CYCLE_TIME unless otherwise specified in this standard.
4 Transport requirements
4.1 Arbitrated short bus reset
All modules or devices which implement this A/M Protocol should have the capability of
"arbitrated short bus reset" in order to prevent the interruption of audio and music data
transmission when a bus reset occurs.
4.2 Bit, byte, and quadlet ordering
This document adopts the ordering of bit, byte, and quadlet for bus packets in accordance
with the IEEE 1394 standard.
5 Packet header for audio and music data
5.1 Isochronous packet header format
The header for an isochronous packet which conforms to the A/M Protocol shall have the
same format given in Figure 1, which is part of the isochronous packet format defined in IEEE
1394: 1995.
data_length tag channel tcode sy
header_CRC
IEC  2358/02
Figure 1 – Isochronous packet header
The isochronous packet header fields are defined with unique values that are specified in
Table 1.
– 8 – 61883-6  IEC:2002(E)
Table 1 – Isochronous packet header fields

Field Value Comments
tag 01 b This value indicates that a CIP header is included in the packet.

tcode A This value indicates that this is an isochronous data packet.
sy xx This field is reserved. The transmitter shall set this field to 0
unless specified by another application.

5.2 CIP header format
IEC 61883-1 defines a two-quadlet CIP header for a fixed length source packet with SYT field,
repeated here for clarity as Figure 2. The CIP header format for an isochronous packet which
conforms to the Audio and music data transmission protocol shall use this CIP header.

SPH
0 0 SID DBS FN QPC rsv DBC
1 0 FMT FDF SYT
IEC  2359/02
Figure 2 – Common isochronous packet (CIP) format
Table 2 defines the fields with unique values that are specified by this protocol.
Table 2 – CIP fields
Field Value Comments
FMT 10 This value indicates that the format is for Audio and Music.
FN 0
QPC 0
SPH 0
SYT xx This field shall contain the time when the specified event is to be
presented at a receiver.
FDF xx This field is defined in Clause 7.
6 Packetization
6.1 Packet transmission method
When a non-empty CIP is ready to be transmitted, the transmitter shall transmit it within the
most recent isochronous cycle initiated by a cycle start packet. The behaviour of packet
transmission depends on the definition of the condition in which “a non-empty CIP is ready to
be transmitted.” There are two situations in which this condition is defined:

61883-6  IEC:2002(E) – 9 –
a) In order to minimize TRANSFER_DELAY, the condition of a non-empty CIP being ready

for transmission is defined to be true if one or more data blocks have arrived within an

isochronous cycle. This transmission method is called Non-Blocking transmission, and is

described in detail in 6.4
b) The condition of “non-empty CIP ready” can also be defined as true when a fixed number

of data blocks have arrived. This transmission method is called Blocking transmission, and

is described in Annex A.
6.2 Transmission of timing information

A CIP without a source packet header (SPH) has only one time stamp in the SYT field. If a

CIP contains multiple data blocks, it is necessary to specify which data block of the CIP
corresponds to the time stamp.
The transmitter prepares the time stamp for the data block which meets this condition:
mod(data block count, SYT_INTERVAL) = 0(1)
where
data block count is running count of transmitted data blocks;
SYT_INTERVAL denotes the number of data blocks between two successive
valid SYTs, which includes one of the data blocks with a valid
SYT. For example, if there are three data blocks between two
valid SYTs, then the SYT_INTERVAL would be 4.
The receiver can derive the index value from the DBC field of a CIP with a valid SYT using the
following formula:
index = mod((SYT_INTERVAL - mod(DBC, SYT_INTERVAL)),
SYT_INTERVAL) (2)
where
index is the sequence number;
SYT_INTERVAL denotes the number of data blocks between two successive
valid SYTs, which includes one of the data blocks with a valid
SYT;
DBC is the data block count field of a CIP.
The receiver is responsible for estimating the timing of data blocks between valid time
stamps. The method of timing estimation is implementation-dependent.

6.3 Time stamp processing
A data block contains all data arriving at the transmitter within an audio sample period. The
data block contains all data which makes up an “event”.
The transmitter shall specify the presentation time of the event at the receiver. A receiver for
professional use shall have the capability of presenting events at the time specified by the
transmitter. A consumer-use or cost-sensitive receiver is not required to support this
presentation-time adjustment capability.
If a function block receives a CIP, processes it and subsequently re-transmits it, the SYT of
the outgoing CIP shall be the sum of the incoming SYT and the processing delay.

– 10 – 61883-6  IEC:2002(E)
The transmitter shall add TRANSFER_DELAY to the quantized timing of an event to construct
the SYT. The TRANSER_DELAY value is initialized with the DEFAULT_TRANSFER_DELAY

value. For professional use, TRANSFER_DELAY may be changed to achieve a shorter

TRANSFER_DELAY value, according to the bus configuration. Products for consumer use are

not required to support the modification of TRANSFER_DELAY.

The DEFAULT_TRANSFER_DELAY value is 354,17 + 125 µs, which accommodates the

maximum latency time of CIP transmission through an arbitrated short bus reset.

6.4 Transmission control
Figure 3 illustrates the non-blocking transmission method.
SYT_INTERVAL = 4
Transmitter
isochronous
cycle
event sequence
Fs = 26,7 kHz
CYCLE_TIME
arrival time T1 T2 T3 T4
Packet
DBC 3 6 10 13 16
SYT R1 R2 R3 No Info R4
Receiver
event sequence
index 122 0
CYCLE_TIME
R1 R2 R3 R4
TRANSFER_DELAY
IEC  2360/02
Figure 3 – Non-blocking transmission method
The transmitter shall construct a packet in every nominal isochronous cycle. Each packet
shall comply with the following constraint:

0 <= N <= SYT_INTERVAL (3)
where
N is the number of events in the packet;
In normal operation the transmitter shall not transmit events late, and shall not transmit
packets early. The resulting conditions may be expressed as follows:
Packet_arrival_time_L <= Event_arrival_time[0] + TRANSFER_DELAY (4)
Event_arrival_time[N-1] <= Packet_arrival_time_F (5)
where
Packet_arrival_time_F is the time (measured in µs) when the first bit of the packet
arrives at the receiver;
61883-6  IEC:2002(E) – 11 –
Packet_arrival_time_L is the time (measured in µs) when the last bit of the packet

arrives at the receiver;
Event_arrival_time[M] is the time (measured i
...