1、C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG06.48-2003-MSW-E.DOC 22.10.03 15.07.10 QUESTION ITU-R 48/6 In-service monitoring of perceived audio quality for distribution and broadcasting networks (2003) The ITU Radiocommunication Assembly, considering a) that digital audiovisual and
2、audio 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 and especially audio signals; c) that distribution and broadcasting networks for di
3、gital services and specially audio services are composed of a multiplicity of cascaded links such as satellites, terrestrial radio links, computer networks and wireless broadcasting or cable distribution to the end-user; d) that the whole delivery chain is composed of a multiplicity of cascaded proc
4、essing systems such as converters, encoders, switches, multiplexers, modulators, receivers, etc.; e) that analogue and digital disturbances or errors on the delivery chain introduce different types of impairments on audio signals; f) that some of these disturbances are inaudible because of error con
5、cealment strategies built into the network and do not influence the perceived audio quality; g) that state-of-the-art troubleshooting systems are adequate to detect long duration impairments on audio sequences, but have limited efficiency for in-service detection of short breaks which are more frequ
6、ent on digital services; h) that Recommendation ITU-R BS.1387 offers ways to evaluate the perceived audio quality of mono and stereo signals in the presence of a full-bandwidth unimpaired reference signal; j) that in-service monitoring in general has no access to the full-bandwidth unimpaired refere
7、nce signal; k) that for some channels a low bit-rate side channel is available to be used for service quality monitoring; l) that in-service monitoring has the requirements of low computational complexity and simple user interfaces; m) that different proprietary solutions are proposed but needs for
8、a common standard have been expressed; n) that commercial contracts impose that network operators must keep the perceived audio quality of the delivered services within agreed limits; o) that quality evaluation in general has been recognized both by ITU-R and ITU-T and they both have set up Question
9、s on studies related to this topic; p) that none of these Questions is related to in-service quality monitoring of perceived audio quality, - 2 - 6/1-E C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG06.48-2003-MSW-E.DOC 22.10.03 15.07.10 decides that the following Question should be st
10、udied 1 What are the appropriate methods and techniques for in-service monitoring of perceived quality of audio services carried on broadcasting networks? further decides 1 that cooperation with other ITU and other relevant bodies is required to allow the selection of the methods and techniques; 2 that the studies above should result in ITU-R Recommendations; 3 that the studies should be completed by the year 2005. _
