It is anticipated that there will shortly be a requirement\udfor multimedia terminals that operate via mobile\udcommunications systems. This paper presents a functional specification\udfor such a terminal operating at 32 kb/s in a digital\udEuropean cordless telecommunications (DECT) and universal\udmobile telecommunications system (UMTS) radio network. A terminal\udhas been built, based on a PC with digital signal processor\ud(DSP) boards for audio and video coding and decoding. Speech\udcoding is by a phonetically driven code-excited linear prediction\ud(CELP) speech coder and video coding by a block-oriented hybrid\uddiscrete cosine transform (DCT) coder. Separate channel coding\udis provided for the audio and video data. The paper describes the\udtechniques used for audio and video coding, channel coding, and\udsynchronization. Methods of subjective testing in a DECT network\udand in a UMTS network are also described. These consisted of\udsubjective tests of first impressions of the mobile audio–visual\udterminal (MAVT) quality, interactive tests, and the completion\udof an exit questionnaire. The test results showed that the quality\udof the audio was sufficiently good for comprehension and the\udvideo was sufficiently good for following and repeating simple\udmechanical tasks. However, the quality of the MAVT was not\udgood enough for general use where high-quality audio and video\udwas needed, especially when transmission was in a noisy radio\udenvironment.
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