Program Specific Information (PSI) Table Sections [MPEG Syntax]
One of the characteristics that distinguishes a fully standards-compliant transport stream from a fully standards-compliant program stream is the presence of MPEG-2 program specific information (PSI) in the former.
The highest level in the PSI hierarchy is the Program Association Table or PAT, which simply provides the transport_stream_id of the transport stream and describes where to find the Program Map Table (PMT) sections in the transport stream.
Optionally, the packet id (or pid) where the Network Information Table (NIT) can be found can be published in the PAT. Like all the PSI sections listed below,
PATs must be provided with instances that are currently effective, and may include
"next" editions to inform receivers of changes before they become effective.
There must be one Program Map Table (PMT) section for each program included in
the transport stream. Each PMT section furnishes the program_number for each
program service and gives the pid and stream_type for each program element that
comprises the program service. PMT sections also include variable-length fields
called descriptors that can include optional data describing the entire program
or individual streams within the program service.
Each of the MPEG-2 users, such as ARIB, ATSC, DVB and SCTE may
have imposed additional constraints on the syntax, semantics and use of one or
more of these sections.
This page qwas last modified on August 21, 2009.