Fundamentals and Evolution of MPEG-2 Systems: Paving the MPEG Road

11Other Features of MPEG-2 Systems

Required measures for transport stream usage in error prone environments. Why re-multiplexing of transport streams is needed and what that means for delays and buffering. Commercial breaks in transport stream based broadcast, causing time base discontinuities; associated buffering issues. Statistical multiplexing in broadcast applications. The role of padding and stuffing. The importance of random access and parsing convenience. Options to carry private data. Support of copyright and copy control. Trick mode operation. Issues with single program transport streams and partial transport streams. Carriage of a program stream in a transport stream, the use of PES streams and room created for future extensions.

11.1 Error Resiliency

When transporting an MPEG-2 system stream, errors may occur. Usually, transport systems apply error correction, for example as an integral element of channel coding, as discussed in Figure 9.8, but the error correction capabilities are obviously limited, so that in error prone environments remaining errors in system streams may be expected. Typical errors are packets with a number of uncorrectable erroneous bytes, and lost packets. Video, audio and other elementary stream decoders are sensitive to errors; prior to detecting an error in the received bitstream, these decoders may produce undesirable output signals. To prevent such output, it is desirable to detect data errors at system level and to signal them to the ...