TRANSMISSION OF MPEG-2 ENCODED VIDEO IN ATM NETWORKS

摘要

A telecommunications transmission system adapted for the transmission of MPEG-2 data streams with a variable bit rate includes an encoder and decoder. The encoder includes a system layer multiplexer adapted to empty a video encoder buffer by reading data blocks therefrom, at a bit rate which is constant within a block. The encoder provides a way of realising VBR in an MPEG-2 system layer multiplexer which has been adapted for ATM, and represents a particularly simple implementation of a VBR MPEG-2 encoder having good jitter control. The encoder eliminates the need for a special 'cell shaping' function in order to fulfil a traffic contract. To recover bit timing in the MPEG-2 decoder, data is buffered in a reception buffer. By continuously reading the deviation of the buffer level, i.e. the level to which the buffer is filled with data, from its nominal value, in this buffer, the deviation of the emptying rate of the buffer, from the nominal bit rate, can be controlled with a phase lock loop (PLL), or similar arrangement.