ITU-T - International Telecommunication Union/ITU Telcommunication Sector
适用范围
This Recommendation supports frame accurate signalling of events in MPEG-2 transport streams along with associated descriptive data. This Recommendation supports the splicing of MPEG-2 transport streams for the purpose of Digital Program Insertion@ which includes advertisement insertion and insertion of other content types. An in-stream messaging mechanism is defined to signal splicing and insertion opportunities and it is not intended to ensure seamless splicing. As such@ this Recommendation does not specify the splicing method used or constraints applied to the streams being spliced@ nor does it address constraints placed on splicing devices. A fully compliant MPEG-2 transport stream (either multi program transport stream (MPTS) or single program transport stream (SPTS)) is assumed. No further constraints beyond the inclusion of the defined cueing messages are placed upon the stream. This Recommendation specifies a technique for carrying notification of upcoming Splice Points and other timing information in the transport stream. A splice information table is defined for notifying downstream devices of splice events@ such as a network break or return from a network break. The splice information table@ which pertains to a given program@ is carried in one or more packet identifiers (PIDs) referred to by that program's program map table (PMT). In this way@ splice event notification can pass through most transport stream remultiplexers without need for special processing.