Apart from the coding of audio and video signals (see chapters 3 and 4) the MPEG-2 standard [ISO 13818] also defines the multiplexing of audio, video and auxiliary data into one single bit stream, the so-called MPEG-2 System ([Teichner, Knoll]). The joining together, however, is not the only task of the multiplex. It must also provide transmission capacity for information about the current programme or broadcast and about the transmission path, as well as other information required either for the technical servicing or as a navigational aid through the maze of programmes offered to the viewer. This information was defined by the DVB Project ([ets 468, etr 211]). Further functions covered by the MPEG-2 System are provisions for clock recovery in the decoder, the synchronisation of video and audio in order to retain the synchronism of the lip movements, and the provision of transmission capacity for conditional-access data (cf. chapter 8). These functions are described in the first part of the MPEG-2 standard entitled “Systems”. They cannot be portrayed here in all their dimensions, but the following sections should serve to give an insight into what are sometimes very complex interconnections.
KeywordsEurope Transportation Dition Alloca Demultiplexing
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