1、 International Telecommunication Union ITU-T J.602TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2008) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Transport of Large Screen Digital Imagery Network service operators requirements for real-
2、time transmission of exLSDI signals under parallel processing functionality Recommendation ITU-T J.602 Rec. ITU-T J.602 (06/2008) i Recommendation ITU-T J.602 Network service operators requirements for real-time transmission of exLSDI signals under parallel processing functionality Summary Recommend
3、ation ITU-T J.602 describes network operators requirements with regard to a real-time transmission system applicable to signals in the extended LSDI hierarchy according to Recommendation ITU-T J.601. Source Recommendation ITU-T J.602 was approved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) un
4、der Recommendation ITU-T A.8 procedure. ii Rec. ITU-T J.602 (06/2008) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sec
5、tor (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets ever
6、y four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview
7、, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is volunta
8、ry. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the n
9、egative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve th
10、e use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommenda
11、tion, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http
12、:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T J.602 (06/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative References 1 2.2 Informative References 1
13、3 Terms and definitions . 1 4 Abbreviations 1 5 Target applications 2 6 Requirements 2 6.1 Performance 2 6.2 Functionality. 2 6.3 Interoperability . 3 Appendix I Example of functional components for Transmission System for signals in the extended LSDI hierarchy 4 I.1 Functional Components formulatio
14、n 4 I.2 Encoder. 4 I.3 Transmission system 4 I.4 Decoder. 4 Appendix II Example of software encoder implementation . 5 iv Rec. ITU-T J.602 (06/2008) Introduction The general information about an encoding scheme, a multiplexing scheme and a transport protocol for signals in the extended LSDI hierarch
15、y is listed in Recommendation ITU-T J.601. On the other hand, several trials are currently conducted to evaluate a number of systems for the transmission of such signals, and an international standard which recommends a transmission system is required to maintain functionality and interoperability a
16、t a sufficient level. This Recommendation describes network operators requirements with regard to a real-time transmission system applicable to signals in the extended LSDI hierarchy based on the technologies defined in Recommendation ITU-T J.601. Rec. ITU-T J.602 (06/2008) 1 Recommendation ITU-T J.
17、602 Network service operators requirements for real-time transmission of exLSDI signals under parallel processing functionality 1 Scope This Recommendation specifies network service operators requirements for a real-time transmission system for signals in the extended LSDI hierarchy, including an en
18、coder and a decoder. Appendix II describes, for information purposes, a method based on the use of parallel processing for encoding images in the extended LSDI hierarchy. The described parallel processing includes a spatially segmented method, a temporally interleaved method, a frequency sub-band di
19、vision method and possible hybrid schemes of those methods. NOTE The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T recommendations has not been applied. 2 References 2.1 Normativ
20、e References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revisio
21、n; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Re
22、commendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T J.601 Recommendation ITU-T J.601 (2005), Transport of Large Screen Digital Imagery (LSDI) applications for its expanded hierarchy. ITU-R BT.1769 Recommendation ITU-R BT.1769 (2006), Parameter values for a
23、n expanded hierarchy of LSDI image formats for production and international programme exchange. ITU-R BT.1121-1 Recommendation ITU-R BT.1121-1 (1995), User requirements for the transmission through contribution and primary distribution networks of digital HDTV signals. ITU-R BS.1548-2 Recommendation
24、 ITU-R BS.1548-2 (2006), User requirements for audio coding systems for digital broadcasting. 2.2 Informative References ITU-T J.600 Recommendation ITU-T J.600 (2004), Transport of Large Screen Digital Imagery (LSDI) applications that employ MPEG-2 encoded HDTV signals. 3 Terms and definitions This
25、Recommendation defines no additional term. 4 Abbreviations This Recommendation uses no new abbreviations. 2 Rec. ITU-T J.602 (06/2008) 5 Target applications This Recommendation focuses on a transmission of signals in the extended LSDI hierarchy for contribution and primary distribution purposes. 6 R
26、equirements The network operators requirements below apply, from the stand point of transmission service operators. The network operators requirements focus on operators aspects regarding network interoperability and operation functionality including service provisioning and monitoring in addition t
27、o the fundamental requirements to maintain the transmission service quality itself. 6.1 Performance 1) Encoder processing time The overall encoder process including image and audio buffering, video encoding, audio encoding and system multiplexing should be completed at a speed corresponding to real-
28、time processing. 2) Coding efficiency For video encoding and audio encoding, the coding bit rate should be selected to satisfy contribution and primary distribution quality. Those required quality level should be determined by further study. As the starting point of this study, ITU-R BT.1121-1 and I
29、TU-R BS.1548-2 are appropriate references for video and audio, respectively. In the case that parallel processing is employed for video encoding, motion compensated prediction and rate control should be employed across image processing boundaries to improve coding efficiency. For video encoding, pic
30、ture quality discontinuities should be negligible along boundaries among segmented images, if a parallel processing is adopted for spatially segmented images. 3) Encoding latency For video encoding and audio encoding, the latency due to processing time for encoding a picture and corresponding audio
31、should be uniform and independent of the image resolution in order to achieve a capability of a seamless switching between different hierarchies of the extended LSDI. 4) Video and audio synchronization Video and audio streams should be synchronized within a sufficient accuracy. Especially, lip synch
32、ronization should be accomplished when audio and video streams are encoded simultaneously. 5) Error performance and recovery time Error performance and recovery time should be determined by further study. As the starting point of this study, ITU-R BT.1121-1 and ITU-R BS.1548-2 are appropriate refere
33、nces for video and audio, respectively. 6.2 Functionality To achieve a transmission functionality and a reliable service monitoring, the following requirements apply. 1) Multi-format support A common processing platform may be utilized to support several image resolutions within the range of image s
34、ystem in the extended LSDI hierarchy, specified in ITU-R BT.1769. Rec. ITU-T J.602 (06/2008) 3 2) Notification of spatial dependency The transmission process should be capable of notifying a spatial dependency in a full resolution picture if parallel processing is adopted for spatially segmented ima
35、ges. 3) Notification of resolution layer dependency The transmission process should be capable of notifying a resolution layer dependency if a functionality of a spatial scalability is utilized in a video coding process. 4) Single bitstream support For video signals, a single resolution layer should
36、 be transmitted by a single bitstream as long as applied video coding standard can support the corresponding image resolution, in order to maintain the monitoring precision when commercial measuring equipments fully compliant with a video coding standard are employed. 6.3 Interoperability 1) Bitstre
37、am conformance The transmitted bitstream should comply with international video coding standards as those listed in ITU-T J.601. 4 Rec. ITU-T J.602 (06/2008) Appendix I Example of functional components for Transmission System for signals in the extended LSDI hierarchy (This appendix does not form an
38、 integral part of this Recommendation) I.1 Functional Components formulation To specify the scope of this Recommendation, functional components are formulated as shown in Figure I.1. Each function and implementation example is described. The interface boundary between a network service operator and
39、a service user corresponds to A and D. Figure I.1 Interface among transmission equipments I.2 Encoder The encoder compresses the input video signal in real time, and emits the processed data as a transport format. ITU-T J.601 lists some coding schemes applicable to signals in the extended LSDI hiera
40、rchy. Some implementations employ a parallel processing due to the large amount of video data in the considered signals. I.3 Transmission system ITU-T J.601 lists some transmission mechanism applicable for the transmission of signals in the extended LSDI hierarchy, such as multiplexing or framing me
41、thods as well as transport methods. I.4 Decoder The decoder decompresses the received data and outputs the video signal in real time. ITU-T J.601 lists some coding schemes applicable to signals in the extended LSDI hierarchy. Encoder TransmissionAuthoringA(Video In)B(Transport Out)C(Transport In)Dec
42、oderD(Video Out)DisplayRec. ITU-T J.602 (06/2008) 5 Appendix II Example of software encoder implementation (This appendix does not form an integral part of this Recommendation) The system architecture of software real-time encoder using distributed computing technology is addressed here. In Figure I
43、I.1, the assumed process configuration of coding node is along the MC+DCT coding framework just as in the case of MPEG coding standards. However, the reference architecture itself does not restrict the coding scheme. Since the process conducted by a coding node is provided by software module, shifti
44、ng to another new coding scheme can be realized as well as enabling unsupported coding function within a specific coding scheme just by reloading the proper software module. In order to maintain a high coding efficiency, following framework is introduced. Figure II.I Block diagram of the example enc
45、oder system a) To maintain the high performance in motion compensated prediction, local decoded images stored in a coding node can be referred from the other coding nodes which handle adjacent image segment. b) In order to suppress the picture quality difference among neighbouring image segments, th
46、e front end node conducts the bit assignment for every image segment prior to initializing encoder process for the current video frame. As the additional advantage introduced by applying this mechanism, the active bit allocation among segmented images can be realized, this may achieve a kind of stat
47、istical multiplexing gain. For the prototype encoder, preliminary experiments are conducted on the typical PC cluster equipped with 12 CPUs. In this experiment, the encoder software is based on MPEG-2. As the test sequence for 4K digital cinema (4096 2160, 24 Hz, progressive scan: DCI spec.), DCI St
48、EM (Standard Evaluation Material) is utilized for the experiment. As a pre-process for MPEG-2 based encoding, input signals are converted into YUV format with 4:2:0 chroma sub-sampling. Prediction imageQ VLCCoding nodeFront end nodeK Video FileLocal decoderTOriginalSegmentedframe#1MultiplexerME+Fram
49、ememoryPrediction imageQ VLCLocal decoderTOriginalSegmentedframeME+StreambufferAccessible among nodes#2FramememoryFront end nodeStreambuffer6 Rec. ITU-T J.602 (06/2008) For simplifying a problem, 4K resolution image is divided into 8 segments whose size is 2048 pixels 540 lines, and a coding node is applied for every segments. In order to evaluate the scalability of this scheme, the relation between the number of coding nodes operating simultaneously and the total system performance is observed. At the maximum case, 8 coding nodes are ope
