R&D Report 1996-02 : MPEG-2: Overview of the systems layer P.A. Sarginson The MPEG-2 Systems specification describes how MPEG-compressed video and audio data streams may be multiplexed together with other data to form a single data stream suitable for digital transmission or storage. This Report introduces the principles and terminology of the MPEG-2 Systems layer. The Report covers three main areas: Firstly, the structure of the multiplexes; secondly, the service information that may be present; thirdly, the system of time stamps and clock references used to synchronise related components of a programme at the decoder. Two alternative multiplexes are specified for the MPEG-2 systems layer. The programme stream is biased towards the storage and replay of a single programme from a digital storage device while the transport stream is intended for the simultaneous delivery of a number of programmes over potentially error-prone channels. Both multiplexes facilitate the inclusion of Programme Specific Information detailing the programme(s) and elementary streams present. The multiplexes also use a system of time stamps and clock references to ensure the synchronous replay of related elementary streams and correct buffer behaviour at a decoder. There are many optional syntax elements and many opportunities to include private (user-defined) syntax extensions enabling either multiplex to be optimised to suit a particular application. * This Report is based on two papers prepared for the Institution of Electrical Engineers (IEE) and is published with permission. The papers were written and used by BBC R&D Engineer, P.A. Sarginson; firstly, for the IEE Colloquium at Savoy Place (Jan. 1995):- MPEG-2: A tutorial introduction to the systems layer, and published as IEE Digest 1995/012; and secondly, for the IEE Residential Course, Durham University (July 1995), from a paper entitled:- An introduction to the MPEG 2 transport stream multiplex.