IEC TS 62312-2:2018

IEC TS 62312-2 ®
Edition 2.0 2018-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Guideline for synchronization of audio and video –
Part 2: Methods for synchronization of audio and video systems

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.

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 corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TS 62312-2 ®
Edition 2.0 2018-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Guideline for synchronization of audio and video –

Part 2: Methods for synchronization of audio and video systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.160.01 ISBN 978-2-8322-6219-1

– 2 – IEC TS 62312-2:2018 RLV © IEC 2018
CONTENTS
FOREWORD . 3
INTRODUCTION . 2
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 System model . 7
4.1 Audio and video system . 7
Latency and delay .
4.2 System model . 7
4.3 Audio and video device . 8
4.4 Controller . 9
4.5 Source device and display device . 9
4.6 Controller function of audio and video device . 10
5 Methods for synchronization . 11
5.1 Information for synchronization . 11
5.1.1 Time-code information . 11
5.1.2 Latency information . 11
5.1.3 Synchronization information . 11
5.2 Methods for synchronization . 12
5.2.1 General . 12
5.2.2 Method with time-code information . 13
5.2.3 Method with latency information . 14
5.2.4 Method with synchronization information . 14
5.3 Method with IEC 60958-3 . 14
5.4 Method with IEC 61883-6 . 14
5.5 Method with other interface specifications . 15
Annex A (informative) Information for synchronization . 16
A.1 Time-code information . 16
A.2 Latency information . 16
A.3 Synchronization information . 16
Bibliography . 17

Figure 1 – System model . 7
Figure 2 – Audio and video device . 8
Figure 3 – Information and control in audio and video device . 9
Figure 4 – Source device . 10
Figure 5 – Display device . 10
Figure 6 – Audio amplifier . 10
Figure 7 – Controller function of audio and video device . 11
Figure 8 – Additional delay . 12
Figure 9 – Multiple reproductions . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDELINE FOR SYNCHRONIZATION OF AUDIO AND VIDEO –

Part 2: Methods for synchronization of audio and video systems

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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.

– 4 – IEC TS 62312-2:2018 RLV © IEC 2018
The main task of IEC technical committees is to prepare International Standards. In
exceptional circumstances, a technical committee may propose the publication of a Technical
Specification when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical Specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC 62312-2, which is a technical specification, has been prepared by technical area 11:
Quality for audio, video and multimedia systems, of IEC technical committee 100: Audio,
video and multimedia systems and equipment.
This second edition cancels and replaces the first edition published in 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) fingerprint is newly introduced;
b) addition of the synchronization information from fingerprint (SMPTE spec.);
c) addition of the method for using the above information.
The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
100/3049/DTS 100/3106/RVDTS
Full information on the voting for the approval of this Technical Specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The list of all the parts of IEC 62312, published under the general title Guideline for
synchronization of audio and video, 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 website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• 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 publication using a colour printer.

INTRODUCTION
Audio, video and multimedia systems and equipment have begun to use digital technologies.
Digital systems or equipment may cause delay of audio and video signals because digital
signal processing causes latency and delay. The unevenness of the delay between audio and
video may can cause synchronization problems.
For instance, a digital broadcasting system uses signal compression of audio and video. A
receiver has signal decoders, and this may can cause unevenness of the delay between audio
and video. Digital video signal processing of the display causes a significant delay in the
reproduction time of the video image. Another example is an audio-video system consisting of
a digital media player, an audio amplifier and a display. A digital media player outputs audio
and video signals separately to the amplifier and display through digital interfaces. This may
cause synchronization problems of audio and video when each the processing time of the
each piece of equipment is different.
To solve synchronization problems of audio and video reproduction on the user side, this
document gives guidelines for general methods for the synchronization of audio and video.

– 6 – IEC TS 62312-2:2018 RLV © IEC 2018
GUIDELINE FOR SYNCHRONIZATION OF AUDIO AND VIDEO –

Part 2: Methods for synchronization of audio and video systems

1 Scope
The IEC 62312 series gives guidelines for methods of synchronization of audio and video.
This part of IEC 62312 describes the system model and general methods for the
synchronization of audio and video. The methods exclude the synchronization of the signal
source and the spatial delay of audio reproduction.
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 60958-3:2006, Digital audio interface – Part 3: Consumer applications
IEC 60958-3:2006/AMD2:2015
IEC 61883-6, Consumer audio/video equipment – Digital interface – Part 6: Audio and music
data transmission protocol
SMPTE 12M, Television, Audio and Film – Time and Control Code
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
latency
inevitable delay of the signal that is caused by its principle or unavoidable signal processing
Note 1 to entry: Signal encoding and decoding, signal compression and de-compression, and signal transmission
through interfaces cause latency.
3.2
delay
general meaning of delay other than latency, including delay that is caused by functional
signal processing and delay that is set intentionally
Note 1 to entry: The term "delay" is sometimes used as to meaning latency. In this technical specification, "delay"
is defined as delay other than latency. Functional signal processing causes delay or delay is set intentionally.

3.3
latency information
information of the sum value of latency and delay
3.4
time stamp address
quantized timing in which an event occurs on the basis of a reference clock
4 System model
4.1 Audio and video system
An audio and video system consists of audio and video devices and these devices may can
include digital signal processing that causes latency and delay. Each device is connected to
the other devices by analogue or digital signal interfaces. The final outputs from the audio and
video system to the user are reproduction of audio with speakers and a visual image with a
display device. These reproductions have no information of synchronization and the method
for synchronization should be applied at the stage prior to the final reproduction.
To control synchronization of audio and video, synchronization information should be provided,
and the controller should control the delay of the audio and video devices with the
synchronization information. The synchronization information and the controller signal are
transmitted through digital interfaces or a control line.
4.2 Latency and delay
Latency means an inevitable delay of signal in the audio and video device that is caused by
principle or unavoidable signal processing. For instance, signal encoding and decoding, signal
compression and de-compression, and signal transmission through interface cause latency.
The term “delay” is sometimes used as meaning latency. In this technical specification, “delay”
is defined as delay other than latency. Functional signal processing causes delay or delay is
set intentionally.
4.2 System model
Figure 1 shows the system model.

Figure 1 – System model
Audio and video synchronization of the signal source is out of the scope of this system model
because this model cannot identify it or control it. The audio and video devices have latencies
and delays because of their structure. The system consists of a number of audio and video

– 8 – IEC TS 62312-2:2018 RLV © IEC 2018
devices. The display unit is a visual reproducer, such as a CRT or a flat panel display device.
The speakers are audio reproducers. These display units and speakers are defined as an
ideal device that has no latency. A spatial delay of audio is outside the scope. The lines A and
B in Figure 1 show the border of the control of synchronization; the controller controls latency
and delay in the audio and video devices with the synchronization information.
4.3 Audio and video device
The audio and video device is defined as a device consisting of audio and video units. Each
unit includes latency and delay.
Figure 2 shows a model for an audio and video device. This audio and video device consists
of units that have latencies and delays and signal inputs and outputs.

Figure 2 – Audio and video device
The latency of the unit is defined as L for video and L for audio, and the delay of the unit
vn an
is defined as D for video and D for audio
vn an
where
n  is a numeric number of units;
L is the video latency of the video unit number n;

vn
D is the video delay of the video unit number n;

vn
TL is the total latency of video;

v
TD is the total delay of video;
v
L is the audio latency of the audio unit number n;

an
D is the audio delay of the audio unit number n;
an
TL is the total latency of audio;
a
TD is the total delay of audio.
a
The total value of latency and delay is the sum of each value.
TL = L + L +….+ L
v v1 v2 vn
TD = D + D + ….+ D
v v1 v2 vn
TL = L + L +….+ L
a a1 a2 an
TD = D + D + ….+ D
a a1 a2 an
To control synchronization of audio and video, the audio and video devices should have the
information and control function that processes the synchronization information and control
delay.
The information and control function of the audio and video device is described in Figure 3.
This is a general model that is applied for both the audio part and the video part
independently.
Figure 3 – Information and control in audio and video device
The audio and video signal and the synchronization information from the previous audio and
video device are input into the next audio and video device. The information detection unit
detects the information of synchronization from the input signal, and the controller accesses
the information through the information line.
Signal processing causes delays and latencies, which are TD and TL for video, and TD and
v v a
TL for audio. The controller accesses the information of latencies and delays through the
a
information line.
To control the delay of the audio and video signals of the audio and video device, at least one
controllable delay unit is required. The controller controls the controllable delay unit through
the control line.
4.4 Controller
The controller controls the delay of both audio and video or either audio or video signals with
the controllable delay unit. The controller calculates the value of delay that is necessary to
synchronize the audio and video signals. The method is described in Clause 5.
The controller may be included in the audio and video device, as described in 4.6.
4.5 Source device and display device
Figure 4 shows the source device. The source device is defined as the device that consists of
the signal source and the audio and video device. The latency and delay of the signal source
is outside the scope of this device. The latencies and delays of the source device are defined
as being the same as those of the audio and video device. For instance, a DVD player
consists of the signal source and the audio and video device. In a DVD player, the source
signal is the contents of the DVD disc, and it is assumed to have synchronized audio and
video data. A digital TV tuner consists of the signal source and the audio and video device,
and the signal source is a broadcasting content that is assumed to have synchronized audio
and video data. The signal is carried by an RF signal or data stream with an encoded format,
which causes latencies at the decoding process.

– 10 – IEC TS 62312-2:2018 RLV © IEC 2018

Figure 4 – Source device
Figure 5 shows the display device, such as a video monitor. The display device consists of an
audio and video device and a display unit and speakers. The latencies and delays of the
source device are defined as being the same as those of the audio and video device. The
display device may have only a video part without an audio part.

Figure 5 – Display device
Figure 6 shows the audio amplifier. This consists of only an audio part and drive speakers.

Figure 6 – Audio amplifier
4.6 Controller function of audio and video device
The controller can be equipped as a function of the audio and video device. This case is
described in Figure 7. The information, or synchronization information, and control are
transmitted between devices. The controller is located in the audio and video device that
controls the synchronization.
The information and control line is provided by the digital interface or the network. For
instance, IEC 60958 is a digital audio interface, which carries digital audio data and
information including synchronization information, and IEEE 1394 is a network interface that
carries similar information.
Figure 7 – Controller function of audio and video device
5 Methods for synchronization
5.1 Information for synchronization
5.1.1 Time-code information
Time-code information is given to the original signal of audio and video when they are
recorded as a recording time stamp address. Through the process of editing, post-production
and authoring, the final time code information is given to the signal source of the source
device in order to ascertain the time when the audio and video signals should be reproduced.
This time-code information is used to synchronize audio and video signals in the audio and
video system. The source device reproduces the time-code information from the signal source
and provides this information to the audio and video device with the information line.
The SMPTE time code is used for the original recording time stamp address and may also be
used for the signal source of the source device. In addition, the secondary time code is used
for synchronization. This time code is produced from the original time code, such as the
SMPTE time code. Further details of time-code information are explained in Annex A.
5.1.2 Latency information
"Latency information" is defined as meaning the information of the sum value of latency and
delay. The source device, the audio and video device, the display device or the audio
amplifier causes latency and delay. Latency information is used to know the time difference
between the audio and video signals in each device. The audio and video device provides this
information to the other audio and video devices or the controller with the information line.
The value of latency information is defined in 4.3 as TL , TD and TL , TD . Further details of
a a v v
latency information are explained in Annex A.
5.1.3 Synchronization information
Synchronization information shows the timing when the audio and video signals are captured
as a snapshot at a point where the audio and video are known to be synchronized. This
information is generated from audio and video signal natures at periods in the flow of audio
and video signals, and the information is embedded in or carried with the audio and video
signals. The audio, video and synchronization information is transmitted through a media and,
at the reproduction side, the relative position of video and audio frames with matching
fingerprints are analysed to obtain delay or synchronization information.
One method of synchronization information is the fingerprint information. Fingerprints
calculated using a simple algorithm are made from each audio and video signal. Video
fingerprints and audio fingerprints are generated periodically at the same point in the system
and they are transmitted with the audio and video signals in an established data format which
depends upon the transport mechanism. At the reproduction of these audio and video signals,

– 12 – IEC TS 62312-2:2018 RLV © IEC 2018
these fingerprints are analysed to obtain video delay, audio delay and synchronization
information. Further details of fingerprint information are explained in Annex A.
5.2 Methods for synchronization
5.2.1 General
To synchronize audio and video signals, an additional delay is added to either the audio or
the video signal ahead of another signal of audio or video as compensation for the difference.

Figure 8 – Additional delay
Figure 8 shows the audio and video device with the additional delay unit for audio and video.
This additional delay unit makes the additional delay D and D .
va aa
D is the additional delay for video by the additional delay unit.
va
D is the additional delay for audio by the additional delay unit.
aa
The same model is applied for the source device, the display device and the audio amplifier.
In the audio and video system, the overall value of latency and delay is the sum of all latency
and delay of the audio and video device and the additional delay for audio and video. To
synchronize audio and video, each value should be equal to:
∑(TL + TD + D ) = ∑(TL + TD + Dv )
a a aa v v a
Generally, one additional delay to each audio and video is adequate, because one additional
delay can compensate for the difference in the audio and video system that consists of serial
connection of the audio and video devices. In this case, the condition of overall delay and
latency is:
(∑(TL + TD ))+ D = (∑(TL + TD )) + D
a a aa v v va
One additional delay of either audio or video can achieve synchronization. In this case, at
least one additional delay unit is required in any device of the audio and video system. This is
shown as:
(∑(TL + TD )) + D = (∑(TL + TD ))
a a aa v v
(∑(TL + TD )) = (∑(TL + TD )) + D
a a v v av
In general, the video signal tends to delay more than the audio signal because of its signal
processing in the audio and video device. In this case, the additional delay is added to the
audio signal.
Figure 9 shows the case of multiple reproductions. If the audio and video system has multiple
reproduction devices in multiple branches, the additional delay should be added to each
branch.
Figure 9 – Multiple reproductions
To calculate the value of the additional delay, the synchronization information is used. There
are two types of synchronization information: one is time-code and the other is latency
information.
The controller gathers the synchronization information from the source device, the audio and
video device, the display device and the audio amplifier, and calculates the necessary value
of the additional delay. Then the controller controls the delay value of the additional delay unit
to synchronize audio and video signals. The timing of the execution of this process depends
on the audio and video system. When some event in the audio and video system changes the
overall value of the latency and delay, the controller may execute this control process.
It depends on the audio and video system which device’s synchronization information should
be used and which device is adequate for the addition of the additional delay.
5.2.2 Method with time-code information
To calculate the value of the additional delay, the difference in the time code of the audio and
the video signal is used. The source device reproduces the audio and video time code from
the signal source. This information is transferred through the information line to the audio and
video devices, the display device and the audio amplifier.
In each device, the audio and video time code will differ if that device has different delay and
latency in each audio and video unit.
There are two types of audio and video devices. One is the device that transfers the time-
code information to the next device. The other is the device that has the additional delay unit.
Generally, the former type is the source device that is located in the middle of the audio and
video system. The latter type is the display device and the audio amplifier. However, the type
of device depends on the audio and video system.
In the case of the source device and the middle-located device, this does not reproduce
sound and image but outputs the audio and video signal to the next audio and video device.
The middle device may not have the compensation method and it should transfer the time
code to the next audio and video device.
In the case of the final reproduction device, such as the display device and the audio amplifier,
the additional delay controls the presentation time of audio and video to be synchronized.

– 14 – IEC TS 62312-2:2018 RLV © IEC 2018
5.2.3 Method with latency information
The latency information is used to ascertain how much time is the difference between the
audio and the video signal in the audio and video device. To reproduce audio and video in the
same presentation time, the controller should know each value of the latency information of
the audio and video devices through the information line. In one audio and video device, the
latency information of audio and video is:
TL + TD  and  TL + TD
a a v v
In the system having multiple audio and video devices, the overall value of the latency is the
sum of all the latency information of the audio and video devices as:
∑(TL + TD )  and  ∑(TL + TD )
a a v v
Each audio and video device has its latency information, and the controller asks for the
latency information of each audio and video device. The controller calculates the overall value
of the latency information of audio and video devices. The value of the additional delays, D
aa
and D , is calculated from the value of that overall value of latency information.
va
5.2.4 Method with synchronization information
Synchronization information is typically generated at the time when the original content is
made. This information shows the exact timing of audio and video frames at the time of audio
and video signals are generated, and this information is provided periodically. After
transmission and signal processing through a media, this information allows the video and
audio frames to be rematched. The reproduction system detects the timing of audio and video
signals at that reproduction time; from that, the value of delay between audio and video signal
is obtained.
5.3 Method with IEC 60958-3
Subclause 6.3 of IEC 60958-3:2006/AMD2:2015 specifies information for synchronization in
user data. These are SMPTE time-code information and latency information. Annex T of
IEC 60958-3:2006 describes application cases of synchronization with the SMPTE time-code
and latency information.
IEC 60958-3 is a mono-directional interface and carries audio data and latency information
and has no functionality of control. The latency information is only transmitted to the next
audio and video device. To calculate the overall value of the latency information, each device
adds its latency information to the latency information that is detected from the input signal.
This bucket brigade gives the sum of the latency information from the source device to the
current audio and video device. This information is input to the next audio and video device.
5.4 Method with IEC 61883-6
IEC 61883-6 is based on the 1394 TA specification. This is one of the application
specifications of IEEE 1394. As IEEE 1394 is a bi-directional interface and has a packet
transmission structure, various protocols are transmitted at the same time in packets including
IEC 61883-6. 1394 TA-specified application specifications include the AV/C command that is
used for controlling systems and devices.
To synchronize audio and video with time-code information, the SMPTE Time Code and
Sample Count Transmission Protocol Ver.1.0 (document number 1999024) specifies the
transmission of the SMPTE time code in packets. This specification may be used with
IEC 61883-6.
To synchronize audio and video with latency information, the AV/C Command for AV
Synchronization Version 1.0 (document number 2005005) specifies a method for getting
latency information and controlling latency and delay. This specification may be used with
IEC 61883-6.
In addition, the IEC 60958-conformant data format is defined in IEC 61883-6, and this format
carries the IEC 60958 frame format as it is through IEC 61883-6. The IEC 60958 frame format
is defined in IEC 60958-1. IEC 61883-6 carries IEC 60958 data and its SMPTE time-code and
latency information.
The IEC 60958-conformant data format can be applied to the other interface specification in
the same way as IEC 61883-6 applies.
5.5 Method with other interface specifications
For other interface and control specifications, the system model and the general method for
synchronization described in this document can be applied.

– 16 – IEC TS 62312-2:2018 RLV © IEC 2018
Annex A
(informative)
Information for synchronization
A.1 Time-code information
SMPTE time code is a common time-code information. Other time-code information is
employed for each system, for instance MPEG employs various kinds of time-code information
for their various MPEG specifications.
This information addresses a time address of an audio and video signal that should be
presented; the information is carried with audio and video signals and the information is
addressed at the content production stage.
A.2 Latency information
Latency is caused by signal processing in each device; latency information is recognized by
the audio and video device.
The information is generated by the signal processing stage; the information is carried from
the signal processing stage to the other audio and video devices.
A.3 Synchronization information
This information is different from time-code information. Synchronization information is
synthesized from characteristics of the audio and video signals and embedded in or carried
with the signals, so this information is captured at an originally synchronized state of audio
and video. SMPTE ST-2064 defines the synchronization information called "fingerprint" and
the transport mechanisms for it.

Bibliography
IEEE 1394:1995, Standard for a High Performance Serial Bus
1394TA 2001024, Audio and Music Data Transmission Protocol 2.1
1394TA 1999024, SMPTE Time Code and Sample Count Transmission Protocol Ver.1.0
1394TA 2005005, AV/C Command for AV Synchronization Version 1.0
SMPTE 12M, Television, Audio and Film – Time and Control Code
ST 2064-1:2015, Audio to Video Synchronization Measurement – Fingerprint Generation
ST 2064-2:2015, Audio to Video Synchronization Measurement – Fingerprint Transport

___________
IEC TS 62312-2 ®
Edition 2.0 2018-11
TECHNICAL
SPECIFICATION
Guideline for synchronization of audio and video –
Part 2: Methods for synchronization of audio and video systems

– 2 – IEC TS 62312-2:2018 © IEC 2018
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 System model . 7
4.1 Audio and video system . 7
4.2 System model . 7
4.3 Audio and video device . 7
4.4 Controller . 9
4.5 Source device and display device . 9
4.6 Controller function of audio and video device . 10
5 Methods for synchronization . 11
5.1 Information for synchronization . 11
5.1.1 Time-code information . 11
5.1.2 Latency information . 11
5.1.3 Synchronization information . 11
5.2 Methods for synchronization . 12
5.2.1 General . 12
5.2.2 Method with time-code information . 13
5.2.3 Method with latency information . 14
5.2.4 Method with synchronization information . 14
5.3 Method with IEC 60958-3 . 14
5.4 Method with IEC 61883-6 . 14
5.5 Method with other interface specifications . 15
Annex A (informative) Information for synchronization . 16
A.1 Time-code information . 16
A.2 Latency information . 16
A.3 Synchronization information . 16
Bibliography . 17

Figure 1 – System model . 7
Figure 2 – Audio and video device . 8
Figure 3 – Information and control in audio and video device . 9
Figure 4 – Source device . 10
Figure 5 – Display device .
...