1、 Recommendation ITU-R BT.1122-2(03/2011)User requirements for codecs for emission and secondary distribution systemsfor SDTV and HDTVBT SeriesBroadcasting service(television)ii Rec. ITU-R BT.1122-2 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and
2、 economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are perform
3、ed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to
4、be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be foun
5、d. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radi
6、odetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management S
7、NG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2011 ITU 2011 All rights reserved. No part of thi
8、s publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R BT.1122-2 1 RECOMMENDATION ITU-R BT.1122-2*User requirements for codecs for emission and secondary distribution systems for SDTV and HDTV (1994-1995-2011) Scope This Recommendation defines user re
9、quirements that should be applied for the specifications, design and testing of systems for the secondary distribution and emission of SDTV and HDTV signals. The ITU Radiocommunication Assembly, considering a) that Recommendations ITU-R BT.601 and ITU-R BT.709 define the parameters of Y, CB, CR-base
10、d digital luminance and colour difference signals; b) that signals conforming to that standard are required to be transmitted through digital secondary distribution networks or emission systems (terrestrial, satellite, cable, etc.); c) that coding algorithms have been devised and standards establish
11、ed or proposed to enable such transmission to be effected using bit rate reduction techniques; d) that general advice on methods of assessment is contained within ITU-R texts, and that, in particular, subjective evaluation methods are defined in Recommendations ITU-R BT.500, ITU-R BT.710, and ITU-R
12、BT.1129; e) that such assessment will need to take account of basic picture quality and the failure characteristic in the presence of errors on the transmission and emission link; f) that both the design of codecs and their assessment will need to take account of user requirements; g) that in order
13、to be complete, the user requirements should specify the test procedures and test material that should be used to check that the requirements are being met, noting a) that Recommendation ITU-R BS.1548 specifies the requirements for audio source coding systems used for sound and television broadcasti
14、ng; b) that Recommendation ITU-R BT.1203 provides user requirements for video bit-rate reduction coding of digital TV signals for an end-to-end television system; c) that Recommendation ITU-R BT.1868 describes user requirements for codecs for contribution, primary distribution and SNG networks, reco
15、mmends 1 that the following user requirements should be applied for the specifications, design and testing of systems for the secondary distribution and emission of SDTV and HDTV signals. *This Recommendation should be brought to the attention of Telecommunication Standardization Study Group 9. 2 Re
16、c. ITU-R BT.1122-2 TABLE 1 User requirements for secondary distribution and emission codecs Item Specification Input video signal format Sampling: 4:2:2 (Y, CB, CR) 8 or 10 bits per sample for each component Input audio signal format Sampling: 48 kHz 16 bits or more Number of audio channels Six chan
17、nels for a main audio service (typical, including LFE). Additional channels for a multilingual service and audio services for the hearing and visually impaired may be provided Maximum relative sound/vision delay 2 ms per codec Basic picture quality (in error-free condition)(1)Single codec Quality di
18、fference: 12% with DSCQS method using at least four sequences taken from Recommendation ITU-R BT.1210, at least half of which should be high-activity sequences. The given quality grade should be met using at least 75% of the sequences chosen; the rest must achieve 30%. Codecs in cascade Cascade of o
19、ne contribution codec, one primary distribution codec and one secondary distribution codec. Quality difference: 18% with DSCQS method using at least four sequences taken from Recommendation ITU-R BT.1210, at least half of which should be high-activity sequences. The given quality grade should be met
20、 using at least 75% of the sequences chosen; the rest must achieve 36%. Basic sound quality See Recommendation ITU-R BS.1548, Annex 2 Failure characteristics/error performance Quasi-error-free at decoder input for normal condition Error-concealment functionality is desirable for decoders Vision/audi
21、o failure characteristics Vision failure first Recovery time 500 ms after a break of 50 ms Change in overall delay after signal interruption/major disturbance Less than 20 s Auxiliary signal Auxiliary signals may be provided for data services and access control. DSCQS: double stimulus continuous quality scale. (1)Subjective assessment of picture quality should be carried out in accordance with RecommendationsITU-R BT.500, ITU-R BT.710 and ITU-R BT.1129.
