1、C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG06.109-2003-MSW-E.DOC 22.10.03 15.07.10 QUESTION ITU-R 109/6*In-service monitoring of perceived audiovisual quality for broadcasting and distribution networks (2003) The ITU Radiocommunication Assembly, considering a) that digital audiovis
2、ual services have rapidly developed in the last few years, based on advances in digital signal compression and communication technologies; b) that the digital services are characterized by a multiplicity of signals including video signals, audio signals and programme-related metadata; c) that the sy
3、nchronicity of all components of an audiovisual programme is an important issue; d) that broadcasting distribution and networks for digital systems and especially video services are composed of a multiplicity of cascaded links such as satellites, terrestrial radio links, computer networks and wirele
4、ss broadcasting or cable distribution to the end-user; e) that the whole delivery chain is composed of a multiplicity of cascaded processing systems such as converters, encoders, switches, multiplexers, modulators, receivers, etc.; f) that different components of an audiovisual programme might be tr
5、ansported over different paths; g) that analogue and digital disturbances or errors on the delivery chain introduce different types of impairments; h) that some of these disturbances are unperceivable because of error concealment strategies built into the network and do not influence the perceived a
6、udiovisual quality; j) that state-of-the-art troubleshooting systems are adequate to detect long duration impairments, but have limited efficiency for in-service detection of short breaks which are more frequent on digital services; k) that Recommendation ITU-R BS.1387 offers ways to evaluate the pe
7、rceived audio quality of mono and stereo signals in the presence of a full-bandwidth unimpaired reference signal; l) that several methods to evaluate the perceived video quality in the presence of a full-bandwidth unimpaired reference signal have been proposed; m) that in-service monitoring in gener
8、al has no access to the full-bandwidth unimpaired reference signal; n) that for some channels a low bit rate side channel is available to be used for service quality monitoring; o) that in-service monitoring has the requirements of low computational complexity and simple user interfaces; _ *This Que
9、stion should be brought to the attention of Telecommunication Standardization Study Group 9. - 2 - 6/1-E C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG06.109-2003-MSW-E.DOC 22.10.03 15.07.10 p) that different proprietary solutions are proposed but needs for a common standard have been
10、 expressed; q) that commercial contracts impose that network operators must keep the perceived quality of the delivered services within agreed limits; r) that quality evaluation in general has been recognized both by ITU-R and ITU-T and they both have set up Questions on studies related to this topi
11、c; s) that none of these Questions is related to in-service quality monitoring of perceived quality, decides that the following Question should be studied 1 What are the appropriate methods and techniques for in-service monitoring of perceived audio visual quality for broadcasting and distribution networks? further decides 1 that cooperation with other the ITU-T and other relevant bodies is required to allow the selection of the appropriate methods and techniques; 2 that the studies above should result in ITU-R Recommendations; 3 that the studies should be completed by 2004. _
