MPEG-4 Book, The

7.3. MPEG-4 File Format

Historically, prior to the MPEG-4 standard, MPEG has not had an explicit file format. MPEG-1 and MPEG-2 content typically is exchanged as files that represent, in a sense, a stream ready to be delivered. These files usually have embedded absolute time stamps, and the data often has been fragmented with a particular transport in mind (e.g., MPEG-2 Systems transport stream). These characteristics can make random access difficult and editing or reuse of the streams hard without decoding, demultiplexing, and then rebuilding the stream after editing. In MPEG-4, no single transport protocol is preferred, so fragmenting the data to suit the packet size of a specific protocol was not acceptable.

The MPEG committee sought a life-cycle ...