Difference between Program Stream and Transport Stream

From ISO 13818-1

Transport Stream:

• Transport stream is a stream definition which is tailore for communicating or storing one ore more programs of coded data according to ITU-T Rec. H.262 ISO/IEC 13818-2 and ISO/IEC 13818-3 and other data in environments in which significant errors may occur. Such errors may be manifested as bit value errors or loss of packets.
• Transport Streams May be Fixed or Variable rate. In either case, the constituent elementary stream may be either fixed or variable rate.
• Transport Stream rate is defined by the values and locations of Program Clock Reference (PCR) fields, which in general are separate PCR fields for each program.
• Transport Stream may be constructed from
• a) from one or more elementary coded data streams
• b) from Program Streams
• c) from other Transport Streams which may themselves contain one or more programs.
• Transport Streams are constructed in two layers: a sytem layer and a compression layer. The input stream to the Transport Stream decoder has a system layer wrapped about a compression layer. Inpute Streams to the Video and Audio decoders have only the compression layer.
• Transport Stream system layer is divided into two syb-layers, one for multiplex-wide operations (the Transport stream Packet Layer), and one for stream-specific operations (the PES packet layer).

Program Stream:

• The Program Stream is a stream definition which is tailored for Commnucating or storing one program of coded data and other data in environments where errors are very unlikely, and where processing of system coding e.g by software, is a major consideration.
• Program Streams may be fixed or variable rate. In either case, the consituent elementary streams may be either fixed or variable rate.
• The Program Stream rate is defined by the values and locations of the System Clock Reference (SCR) and mux_rate fields.
• Program Streams are constructed in two layers: a system layer and a compression layer. The inpur to the Program Stream Decoder has a system layer wrapped about a compression layer. Input streams to the video and Audio decoders have only the compression layer.
• The Program Stream system layer is divided into two sub-layers, one for multiplex-wide operations (the pack layer), and one for stream-specific operations (the PES packet layer).