Conditional Access and Scrambling
Jan van der Meer · 2014
For many Moving Picture Experts Group-2 (MPEG-2) system applications, unauthorized access to the content carried in an MPEG-2 system stream is to be prevented. While the specification of conditional access (CA) systems is beyond the scope of MPEG, it is possible to apply practical CA systems in MPEG-2 system based applications. Therefore the use of CA systems in a MPEG-2 system stream is an important design consideration. MPEG-2 systems support scrambling of elementary stream data in transport streams and program streams. This chapter describes scrambling in transport streams and program streams in detail. Irrespective of any applied scrambling, access to encoded fields in PES packet headers remains possible during transport. The chapter also summarizes how a receiver of a transport stream finds the required data for the decoding of a scrambled program, consisting of video and audio streams.