1、Rec. ITU-R BT.1382 1RECOMMENDATION ITU-R BT.1382ASSESSMENT OF THE PICTURE QUALITY OF MULTI-PROGRAMME SERVICES(Question ITU-R 211/11)(1998)Rec. ITU-R BT.1382The ITU Radiocommunication Assembly,consideringa) that a number of administrations are studying or planning the introduction of multi-programme
2、televisionservices;b) that a variety of media with different transmission characteristics may be used for the delivery ofmulti-programme services including terrestrial, satellite and cable;c) that several Working Parties in ITU-R are investigating multi-programme services;d) that the total transmiss
3、ion capacity of broadcast channels is limited and has to be shared among services;e) that service providers may want to have the flexibility to dynamically allocate channel capacity to each servicein order to make efficient use of the total channel capacity;f) that multi-programme services may inclu
4、de 3D (Stereoscopic) television;g) that statistical redundancy techniques such as statistical multiplexing or joint coding may be applied to increasethe number of programme services carried within the multiplex or to improve the quality of programmes within themultiplex;h) that the picture quality o
5、f individual programmes may vary according to the instantaneous bit rate allocated tothe programme services, and to the scene content of all programmes;j) that it is possible that individual channels within a multi-programme multiplex may be thematically based;k) that single stimulus subjective proc
6、edures may be more appropriate to assess individual thematic programmes;l) that channels may occasionally suffer uncorrected errors which will make it important to assess the behaviourof multi-programme services as they pass from normal operation to failure;m) that the use of high levels of digital
7、compression on multi-programme services may introduce a non-negligibleamount of coding delay,recommends1 that, for subjective assessment of the quality of individual programmes compressed and coded with ConstantBit Rate (CBR) within a multi-programme service, subjective procedures detailed in Recomm
8、endations ITU-R BT.500and 1129 and the procedure described in Annex 1 should be used;2 that, for subjective assessment of the quality of individual programmes compressed and coded with VariableBit Rate (VBR) by using methods such as statistical multiplexing or joint coding within a multi-programme s
9、ervice,subjective procedures detailed in Recommendations ITU-R BT.500 and 1129 and the procedure described in Annex 2should be used;3 that assessments of the quality of thematically based channels should be undertaken using test material ofsimilar content and criticality to that which would usually
10、be transmitted on those channels;4 that, to assess the overall perceived quality of programming which varies in “instantaneous” quality over aperiod of time, the procedures described in Annex 1 and Annex 2 should be used;2 Rec. ITU-R BT.13825 that scaling of results for systems involving low quality
11、 references, according to the comments included in thedescription of the DSCQS method within Recommendation ITU-R BT.500, should be applied and further studied fortesting which compares multi-programme services against low quality material;6 that the guidance on subjective assessment of failure char
12、acteristics described in Annex 3 should be applied inaddition to information given within Recommendation ITU-R BT.1129;7 that procedures detailed in Annex 3 should be used for assessing the subjective performance of errormitigation strategies, such as freezing the last valid image, or “graceful degr
13、adation” coding;8 that procedures detailed in Annex 4 for subjectively assessing viewer tolerance for delays in acquisition ofnewly selected programmes from a multi-channel multiplex should be applied.ANNEX 1Subjective picture quality assessment procedures forconstant bit rate multi-programme servic
14、esVideo Services may include SDTV and HDTV 2D or 3D (stereoscopic) video programmes.1 2D Video ProgrammesThe subjective picture quality assessment for each SDTV programme can be carried out independently using themethods described in Recommendation ITU-R BT.1129. For the assessment of the system bas
15、ic quality, the general testmethod DSCQS (described in Recommendation ITU-R BT.500) should be used. For the assessment of programmes withtransmission impairments the general test method DSIS (described in Recommendation ITU-R BT.500) should be used.The subjective picture quality assessment for each
16、HDTV programme can be carried out independently using themethods described in Recommendation ITU-R BT.710 or, if possible, with the test procedures recommended for SDTVwith appropriate modifications. For the system basic quality, the general test method DSCQS (described inRecommendation ITU-R BT.500
17、) should be used. For the assessment of programmes with transmission impairments thegeneral test method DSIS (described in Recommendation ITU-R BT.500) should be used.Test procedures to assess the overall picture quality for programmes with instantaneously varying quality have to bedeveloped.2 3D (S
18、tereoscopic) Video ProgrammesFor the subjective picture quality assessment for each 3D (stereoscopic) video programme, the methods on subjectiveassessment of stereoscopic television pictures are under development.Rec. ITU-R BT.1382 3ANNEX 2Subjective picture quality assessment procedures forvariable
19、 bit rate multi-programme servicesFor the subjective picture quality assessment of SDTV and HDTV 2D and 3D (stereoscopic) programmes new testprocedures have to be developed including test procedures to assess overall picture quality for programmes withinstantaneously varying quality. So far the test
20、 method DSCQS (described in Recommendation ITU-R BT.500) has beenused for the SDTV 2D multi-programmes using variable bit rate coding. However, further data is required to verify theappropriateness of this method. Attention must also be drawn to the selection of test materials, since the picture qua
21、litymay depend on the picture content of all the multiplexed programmes.ANNEX 3Subjective assessment of failure characteristics and error mitigationThis type of assessment is still under study and new procedures have to be developed.ANNEX 4Subjective assessment of channel hopping delaysThis type of assessment is still under study and new procedures have to be developed.
