[linux-dvb] Re: PAT/PMT decoding

[Felix Domke <tmbinc@elitedvb.net>]

Aurelian Pop wrote:
> If section_number = last_section_number = 0 it means that PAT is formed 
> of only one TS packet, and all the information about the programs (in 
> fact the different PMTs) exists in those 45 bytes that you say the 
> section_lenght is.
It says that all information is contained in one SECTION, which can span 
along multiple TS packets. One (as in this case) or multiple (up to 256 
with last_section_number = 0xFF) section form one table. One section can 
be up to 1024 (all except EIT) or 4096 bytes (EIT).



>     47 40 00 1f 
the ts header, pid 0, CC=0xF, PUSI=1, no adaption field but payload.
>     00
since PUSI is one, the first byte is a pointer to the section data 
(starting from the byte after the pointer). data before this pointer 
belongs to the last section. as it is 0, a new section start immediately 
after the 00.

> 00
table id is 0
> b0 2d
length is 0x2d
> 07 f3
tsid is 0x07F3.
> ef
version is 46d
> 00 00 
first/last section number

now, we have (0x2d-5) = 40d bytes left. 4 bytes are CRC, so we have 36 
bytes data left. these data defines the PAT. there is no counter or 
something like this, since all data belong to the assosiation between 
SID and PMTPID.

> 00 00 e0 10
ok, the special case: 0000 means NIT and is usually on pid 0x10

> 12 08 e1 04 
> 14 56 e1 03
> 14 78 e1 06
> 14 79 e1 07
> 14 ab e1 05
> 15 82 e1 00
> 16 aa e1 02
> 16 ac e1 01
the services in this TS (36/4 =  9 services including NIT entry)
> 94 71 3f de
the crc.

since no other sections are available, that's the whole PAT.


bye,
felix



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