I am familiar with other MPEG Systems specifications. What is different in MPEG-4 Systems?
MPEG-2 Systems specifies a transport layer facility with the MPEG-2 Transport Stream and Program Stream constructs. The MPEG-1 Systems design is essentially identical to the MPEG-2 Program Stream structure. MPEG-4 addresses the coded representation of audio-visual objects, both natural and synthetic. The MPEG-4 Systems layer addresses how these objects are composed together to form a scene (composition information or scene description), as well as how a user may interact with such objects. This scene description feature is the main innovation in terms of Systems expertise. In addition, the object based architecture of MPEG-4 necessitates changes in the way audio-visual information is managed. Therefore, and more in the tradition of the MPEG-1/2 Systems expertise, MPEG-4 Systems provides a flexible architecture for the delivery of the MPEG-4 data. This architecture consists in the Elementary Stream Management framework (ESM) as well as an abstraction of the specific delivery mechanisms
