1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T J.604 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2014) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS Transport of Large Screen Digital Imagery Requirements fo
2、r a scalable video transmission system over cable networks Recommendation ITU-T J.604 Rec. ITU-T J.604 (01/2014) i Recommendation ITU-T J.604 Requirements for a scalable video transmission system over cable networks Summary Recommendation ITU-T J.604 describes requirements for a scalable video trans
3、mission system over cable networks, which is one of the transmission methods for providing additional high resolution video services. High resolution video formats such as 4K are expected to be one of the ultra-realistic video formats that will be applied to future video services over cable network
4、infrastructures. In the beginning of 4K video (ITU-R BT.1769/ITU-R BT.2020) services, both high definition television (HDTV) and 4K video services will be simultaneously provided. Considering the cost of constructing the infrastructure, the current and new services will be provided over the same cab
5、le network infrastructure. Furthermore, in the case where the 4K video service will be additionally provided over the existing cable network infrastructure, the signal receiver (e.g., the set top box (STB) device) should be replaced with one that supports the 4K service. However, it is difficult to
6、change all STB devices in the existing service at the same time, and therefore the 4K service will coexist with the current HDTV service. Distribution systems using scalable video coding technology are one of the effective methods for providing simultaneous services. Within a general scalable video
7、coding method, the smallest resolution video is coded as the low layer, and then the higher resolution video is coded as the higher layer by encoding the difference information from the lower resolution video. From the viewpoint of compatibility to the current cable services which employs radio freq
8、uency (RF)-based broadcasting, one solution is that the existing HDTV service over RF is also used as the low layer, and then the difference information between 4K video and HDTV may be transmitted as the higher layer over the IP interface (data over cable service interface specification (DOCSIS) IT
9、U-T J.222.0). This Recommendation includes requirements regarding general issues, scalability of video service, and system performance. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T J.604 2014-01-13 9 11.1002/1000/12105-en _ * To access the Recommendation, type the URL htt
10、p:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T J.604 (01/2014) Rec. ITU-T J.604 (01/2014) iii FOREWORD The International Telecommunication Union (ITU) is the United Nations
11、 specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on
12、them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of IT
13、U-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, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is us
14、ed for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with th
15、e Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of
16、 any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Pro
17、perty Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, i
18、mplementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior wr
19、itten permission of ITU. iv Rec. ITU-T J.604 (01/2014) Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 Total configuration . 2 6.1 Acquisition . 2 6.2 Gener
20、ation 2 6.3 Encoding . 3 6.4 Decoding . 3 7 Requirements 3 7.1 General . 3 7.2 Scalability . 3 7.3 Functionality . 4 7.4 Performance 4 Appendix I Example of a scalable video transmission system based on the existing standard . 5 I.1 Example configuration of a scalable video transmission system . 5 A
21、ppendix II Example of a scalable video transmission system using several video coding standards . 6 II.1 Example configuration of a scalable video transmission system . 6 Bibliography. 7 Rec. ITU-T J.604 (01/2014) 1 Recommendation ITU-T J.604 Requirements for a scalable video transmission system ove
22、r cable networks 1 Scope This Recommendation specifies requirements with regard to a scalable video transmission system over cable networks, which is one of the approaches for transmitting an additional video service (e.g., 4K) over cable networks on top of the existing video service (e.g., high def
23、inition television (HDTV). Furthermore, this system supports scalable video coding bitstreams, which consist of a multi-layer bitstream structure, and that complies with video coding technology standards. In order to enable the provision of simultaneous video services over cable networks, this syste
24、m transmits individual layer bitstreams over radio frequency (RF) and IP (data over cable service interface specification (DOCSIS) ITU-T J.222.0). This Recommendation is most suitable for the case where a bit rate reduction is the highest priority because the available transmission capacity of the I
25、P (DOCSIS) interface is insufficient for transmitting several higher quality video programs (e.g., 4K), or the remaining RF bandwidth is not sufficient to convey such programs. Another applicable case is that the gain of scalable coding is sufficiently larger than independent coding, or more specifi
26、cally, scalable transmission is capable of reducing the bit amount of the higher layer (quality) stream against a simultaneously coded stream. Here, an assumption is that the higher quality video and the legacy quality video have identical angles of view, and it helps to achieve good coding gain in
27、scalable coding. 2 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 s
28、ubject to revision; 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 docume
29、nt within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T J.222.0 Recommendation ITU-T J.222.0 (2007), Third-generation transmission systems for interactive cable television services IP cable modems: Overview. 3 Definitions 3.1 Terms defined els
30、ewhere None. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AVC Advanced Video Coding DOCSIS Data Over Cable Service Interface Specification HD High Definition 2 Rec. ITU-T J.604 (01/2014) HDTV High Defin
31、ition Television HEVC High Efficiency Video Coding QAM Quadrature Amplitude Modulation RF Radio Frequency STB Set Top Box SVC Scalable Video Coding 5 Conventions In this Recommendation, the following conventions are used. The keywords “is required to“ indicate a requirement which must be strictly fo
32、llowed and from which no deviation is permitted if conformance to this Recommendation is to be claimed. The keywords “is recommended“ indicate a requirement which is recommended, but which is not absolutely required. Thus this requirement need not be present to claim conformance. The keywords “is pr
33、ohibited from“ indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed. The keywords “can optionally“ indicate an optional requirement which is permissible, without implying any sense of being recommended.
34、 This term is not intended to imply that the vendors implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification. In the bo
35、dy of this Recommendation and its annexes, the words shall, shall not, should, and may sometimes appear, in which case they are to be interpreted, respectively, as is required to, is prohibited from, is recommended and can optionally. The appearance of such phrases or keywords in an appendix or in m
36、aterial explicitly marked as informative are to be interpreted as having no normative intent. 6 Total configuration The configuration of the scalable video transmission system in this Recommendation is shown in Figure 1. The major processing of the system includes: acquisition, generation, encoding
37、and decoding. Figure 1 Configuration of the scalable video transmission system 6.1 Acquisition A high quality video signal (e.g., high resolution, high frame rate or high signal-to-noise ratio (SNR) is acquired by either a camera or another video source signal. 6.2 Generation For input to the scalab
38、le video transmission system, several types of videos are generated from the original video signal. In the case of a simultaneous service, the low quality video may be generated from the high quality video by using a down-converting filter. Rec. ITU-T J.604 (01/2014) 3 6.3 Encoding Multi-format vide
39、os are efficiently encoded based on scalable video coding technology. Initially, the low quality video is encoded as the low layer of scalable video coding, which is compatible with single layer video coding. Before encoding the high quality video on the higher layer, the low layer signal is locally
40、 decoded and up-converted to the high quality video. The locally decoded signal contributes to efficient estimation for the higher layer coding. Therefore, the difference signal information between the high quality video and the low quality video is encoded on the higher layer. Regarding the transmi
41、ssion process of scalable video transmission systems over cable networks, each layer bitstream is independently transmitted over a different interface. The low layer and the higher layer are transmitted over RF and IP (DOCSIS ITU-T J.222.0) interfaces, respectively. 6.4 Decoding A multi-format video
42、 stream is decoded based on scalable video decoding technology. The bitstreams of the low layer and the higher layer are sequentially decoded for presenting original video since the higher layer decoding process requires the decoded and up-converted low layer signal. 7 Requirements The following req
43、uirements from the standpoint of transmission service operators are considered. 7.1 General (1) Simultaneous service Video service based on this transmission system is required to be compatible with the current cable service. In the case that the current service (e.g., high definition television (HD
44、TV) is based on quadrature amplitude modulation (QAM), an additional service (e.g., 4K) using the QAM and/or IP interface is required not to affect the current service. (2) Transmission Each layer bitstream of scalable video is recommended to be independently transmitted over a different interface.
45、(3) Decoding process In order to decode a scalable video stream, the decoding process for an additional service (e.g., 4K) is required to synchronize each layer of bitstream that is individually transmitted over QAM and IP interfaces. 7.2 Scalability The transmission system is required to support ei
46、ther one or both types of the following scalabilities: 1. Resolution scalability The low layer bitstream contains the encoded video sequence with the minimum resolution, and the higher layer bitstream(s) contains the encoded video sequence(s) with higher resolution(s). 2. Temporal scalability The lo
47、w layer bitstream contains the encoded video sequence with the lowest frame rate, and the higher layer bitstream(s) contains the encoded video sequence(s) with the higher frame rate(s). 4 Rec. ITU-T J.604 (01/2014) 7.3 Functionality (1) Bitstream conformance The transmitted bitstream is recommended
48、to be compliant with international standards of transport and video coding. (2) Error correction Error correction information is recommended to be included in the transport stream for each layer bitstream. In the case where the transport stream is partially damaged, the transmission error is recomme
49、nded to be corrected on the decoder side. 7.4 Performance (1) Processing time The processing time for decoding the scalable video stream is required to be faster than real-time displaying. (2) Latency The arrival latency to the decoder side between bitstream layers, which includes transmission latency between QAM and IP interfaces, is required to be limited to a range of time which enables the decoding process to synchronize between bitstream layers. Rec. ITU-T J.604 (01/2014) 5 Appendix I Example of a scalable video transmission system base
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