Protocol and procedure for time base change in an MPEG-2 compliant datastream

摘要

A method of implementing a time base change to a time-division multiplexec bitstream, for example an MPEG-2-compatible bitstream. The time base change is in response to a Time Base Change Flag. The bitstreams have video and audio packetized elementary streams, and each of these streams has a common time base. Each of the packetized elementary streams has a packet header, and packet data. The packet headers of the packetized elementary streams each contain a Presentation Time Stamp/Decoding Time Stamp flag field, a Presentation Time Stamp field, and a Decoding Time Stamp field. A time base change is indicated by a change in the PCR. The first step in changing the Time Base is receiving a discontinuity in the bitstream. This is used to disable synchronization of the video and audio bitstreams, and to mark a data byte in the bitstream associated with the Time Base Change Flag. The time base change is carried out and an interrupt is issued when the marked data byte arrives for decoding. This interrupt re-enables synchronization of the audio and video bitstreams.