Program map table

In DVB digital television , the Program Map Table (PMT) contains the references to the video, audio and other data streams ( elementary streams ) belonging to a program . The content of the table is specified in MPEG-2 Part 1, Systems ( ISO / IEC 13818-1).

With the help of the information contained in this table, a receiver is able to configure the decoders of the individual elementary streams and to start the actual decoding process.

The PIDs of the various PMTs in a TS are referenced in the Program Association Table (PAT).

construction

The PMT consists of one section for each program advertised in the PAT. The individual sections are usually sent on different PIDs, but this is not mandatory.

Each section (which contains a maximum of 1 kilobyte of binary data) contains the following information:

• Table identification (table_id) with the value 0x02.
• Program identification (program_number), these values ​​are identical to those in the PAT.
• Specification of the PID (PCR_PID) which contains the Program Clock Reference (PCR) for this program. In the event that no such value exists, the PID of the null packets (0x1FFF) is transmitted here.
• Information for each individual elementary stream
  • Type of elementary stream (stream_type), e.g. B. MPEG-2 video (0x02), MPEG audio (0x03), private data (also teletext) (0x06).
  • PID on which the elementary stream is transmitted.
  • More specific information in the form of descriptors .

Individual evidence

1. ^ Keith Jack: Video Demystified, Fifth Edition , 2007, pp. 670-671. ISBN 978-0-7506-8395-1