Transmisjon av MPEG-kodet data i ATM-systemer

摘要

The invention provides a MPEG-2 broadband multimedia terminal for audiovisual communication, or distribution, including a MPEG-2 encoder, a MPEG-2 decoder, a workstation for the presentation of audio, visual and data signals generated by the MPEG-2 decoder, and a control unit for overall management and control of said terminal. The MPEG-2 encoder and decoder have architectures for implementation of ATM-adapted system layer multiplexing and demultiplexing, respectively. The encoder includes a multiplexing unit for packeting and multiplexing audio and video signals in accordance with MPEG-2 and for generating a MPEG-2 transport stream for application to an ATM Adaption Layer (AAL). The multiplexing unit is adapted to divide each MPEG-2 data packet, in the MPEG-2 transport stream, into a number of separate data packets for application to the AAL and to add a status byte to each of the data packets prior to application to the AAL. The MPEG-2 decoder, wherein MPEG-2 system layer decoding includes demultiplexing of the different elementary streams contained within the system layer, and wherein AAL SAR-PDU payload units, extracted from ATM cells, are converted into MPEG-2 data packets, is adapted to convert the AAL SAR-PDU payload units into MPEG-2 data packets, on a cell basis, as part of the MPEG-2 demultiplexing. The AAL SAR-PDU payload units may each include a status byte which indicates, by means of a VCI, the channel over which an associated cell has been transmitted. The status byte may also indicates if an associated data block contains a MPEG-2 packet header.