ISO/IEC 13818-1 2013 specifies the system layer of the coding. It was developed principally to support the combination of the video and audio coding methods defined in ISO/IEC 13818-2 and ISO/IEC 13818-3. The system layer supports six basic functions
- the synchronization of multiple compressed streams on decoding;
- the interleaving of multiple compressed streams into a single stream;
- the initialization of buffering for decoding start up;
- continuous buffer management;
- time identification;
- multiplexing and signalling of various components in a system stream.