1、 TECHNICAL SPECIFICATION IEC TS 62312-2First edition 2007-06Guideline for synchronization of audio and video Part 2: Methods for synchronization of audio and video systems Reference number IEC/TS 62312-2:2007(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2007 IEC, Geneva, Switzerland All righ
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8、-2First edition 2007-06Guideline for synchronization of audio and video Part 2: Methods for synchronization of audio and video systems PRICE CODE P For price, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission 2 TS 62312-2 IEC:2007(E) CONTENTS
9、FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms and definitions .6 4 System model.7 4.1 Audio video system .7 4.2 Latency and delay .7 4.3 System model .7 4.4 Audio and video device .8 4.5 Controller 9 4.6 Source device and display device9 4.7 Controller function of audio and v
10、ideo device 10 5 Methods for synchronization.11 5.1 Information for synchronization11 5.1.1 Time-code information.11 5.1.2 Latency information .11 5.2 Methods for synchronization11 5.2.1 General .11 5.2.2 Method with time-code information 13 5.2.3 Method with latency information 14 5.3 Method with I
11、EC 60958-3 14 5.4 Method with IEC 61883-6 14 5.5 Method with other interface specifications .15 Bibliography16 Figure 1 System model 7 Figure 2 Audio and video device 8 Figure 3 Information and control in audio and video device9 Figure 4 Source device 10 Figure 5 Display device10 Figure 6 Audio ampl
12、ifier.10 Figure 7 Controller function of audio and video device .11 Figure 8 Additional delay .12 Figure 9 Multiple reproductions13 TS 62312-2 IEC:2007(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ GUIDELINE FOR SYNCHRONIZATION OF AUDIO AND VIDEO Part 2: Methods for synchronization of audio and v
13、ideo 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 standardi
14、zation 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 i
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22、on 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
23、shall not be held responsible for identifying any or all such patent rights. 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
24、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 sub
25、ject 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 IEC technical committee 100: Audio, video and multimedia systems and equipment. 4 TS 62312-2 IEC:2007(E) The
26、text of this technical specification is based on the following documents: Enquiry draft Report on voting 100/1195/DTS 100/1226/RVC 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 publication has b
27、een drafted in accordance with the ISO/IEC Directives, Part 2. The list of all the parts of IEC 62312, 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 unti
28、l 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 transformed into an International standard, reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual
29、version of this publication may be issued at a later date. TS 62312-2 IEC:2007(E) 5 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
30、latency and delay. The unevenness of the delay between audio and video may cause synchronization problems. For instance, a digital broadcasting system uses signal compression of audio and video. A receiver has signal decoders, and this may cause unevenness of the delay between audio and video. Digit
31、al video signal processing of 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 display. A digital media player outputs audio and video signals separately to the amplif
32、ier and display through digital interfaces. This may cause synchronization problems of audio and video when each processing time of the equipment is different. To solve synchronization problems, this technical specification gives guidelines for general methods for the synchronization of audio and vi
33、deo. 6 TS 62312-2 IEC:2007(E) 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
34、 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 referenced documents are indispensable for the application of this document. For dated references, only
35、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 61883-6, Consumer audio/video equipment Dig
36、ital interface Part 6: Audio and music data transmission protocol 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 latency inevitable delay of signal that is caused by principle or unavoidable signal processing 3.2 delay general meaning of del
37、ay other than latency, including delay that is caused by functional signal processing and delay that is set intentionally 3.3 latency information information of the sum value of latency and delay 3.4 time stamp quantized timing in which an event occurs on the basis of a reference clock TS 62312-2 IE
38、C:2007(E) 7 4 System model 4.1 Audio video system An audio video system consists of audio and video devices and these devices may include digital signal processing that causes latency and delay. Each device is connected to the other device by analogue or digital signal interfaces. The final outputs
39、from the audio video system to the user are reproduction of audio with speakers and visual image with 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 synchronizati
40、on 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 control line
41、. 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.
42、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. 4.3 System model Figure 1 shows the system model. Signal source Audio and video Devices 1 D
43、 Speakers Audio Video Video Audio Controller B Information and control line Devices n A Video Audio Information Audio and video IEC 979/07 Figure 1 System model In this system model, audio and video synchronization of the signal source is outside the scope because this model cannot identify it or co
44、ntrol it. The audio and video devices have latencies and delays because of their structure. The system consists of a number of audio and video devices. The display unit is a visual reproducer such as CRT or a flat panel display device. The speakers are audio reproducers. These display unit and speak
45、ers are defined as an ideal device that has no latency. A spatial delay of audio is outside the scope. The lines A and B show the border of the control of synchronization, the controller controls latency and delay in the audio and video devices with the synchronization information. 8 TS 62312-2 IEC:
46、2007(E) 4.4 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 audio and video device. This audio and video device consists of units that have latencies and delays and signal i
47、nputs and outputs. Audio Video Audio and video device Audio Video L v1 Inputs Outputs L a1 L vnL anD vn D an D v1 D a1 TL v+ TD v TL a+ TD a IEC 980/07 Figure 2 Audio and video device The latency of the unit is defined as L vnfor video and L anfor audio, and the delay of the unit is defined as D vnf
48、or video and D anfor audio where n is a numeric number of units; L vn is the video latency of the video unit number n; D vnis the video delay of the video unit number n; TL v is the total latency of video; TD vis the total delay of video;L an is the audio latency of the audio unit number n; D anis t
49、he audio delay of the audio unit number n; TL ais the total latency of audio; TD ais the total delay of audio. The total value of latency and delay is the sum of each value. TL v= L v1+ L v2+ L vnTD v= D v1+ D v2+ + D vnTL a= L a1+ L a2+ L anTD a= D a1+ D a2+ + D anTo control synchronization of audio and video, the audio and video devices should have the information and control function that processes the syn
