PAT (program Association Table)
| When exists | Name | Number of bits |
Description |
|---|---|---|---|
| If TS payload unit start |
Pointer field | 8 | Present if payload_unit_start_indicator bit is set in the TS header bytes. Gives the number of bytes from the end of this field to the start of payload data. |
| Table ID | 8 | 0x00 | |
| Section syntax indicator | 1 | Always 1 for PAT | |
| 0 | 1 | Always 0 for PAT | |
| Reserved | 2 | Always set to binary '11' | |
| Section length | 2+10 | Informs how many programs are listed below by specifying the number of bytes of this section, starting immediately following this field and including the CRC. First two bits must be zero. | |
| transport stream ID | 16 | User defined data. Value not important to demuxers or players. | |
| Reserved | 2 | Always set to binary '11' | |
| Version number | 5 | Table version number. Incremented by 1 when data in table changes. Wraps around from 31 to 0. | |
| Current/next indicator | 1 | If 0, table data isn't applicable yet (becomes applicable when set to 1) | |
| Section number | 8 | Index of this section in the sequence of all PAT table sections. First section is numbered 0 | |
| Last section number | 8 | Index of last section of PAT table | |
| Repeated N times depending on section length |
Program num | 16 | |
| Reserved | 3 | Always set to binary '111' | |
| Program PID | 13 | packets with this PID are assumed to be PMT tables (see below) | |
| CRC32 | 32 | ||
The PAT is assigned PID 0x0000 and table id of 0x00. The transport stream contains at least one or more TS packets with PID 0x0000. Some of these consecutive packets form the PAT. At the decoder side the PSI section filter listens to the incoming TS packets. After the filter identifies the PAT table they assemble the packet and decode it. A PAT has information about all the programs contained in the TS. The PAT contains information showing the association of Program Map Table PID and Program Number. The PAT should end with a 32-bit CRC
Read more about this topic: Program-specific Information
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