ABSTRACT
Audio and video encoders deliver as their output elementary streams which are the constituents of the so-called compression layer. Each elementary stream carries access units which are the coded representations of presentation units, i.e. decoded pictures or audio frames depending on the nature of the elementary stream. A complete MPEG-1 system encoding device therefore has to effect video and audio encoding, the multiplexing of these data, private data and the necessary information to synchronize the audio and video parts of the decoder, and to indicate the necessary resources required for decoding the MPEG-1 bitstream. Each elementary stream is cut into packets to form a packetized elementary stream (PES); a packet starts with a packet header followed by the elementary stream's data. The chapter details the different fields of an MPEG-1 packet. In the same way as for MPEG-1, MPEG-2 elementary streams are packetized in order to form the video, audio and private data PESs.
