[linux-dvb] parsing of EIT problems

Rainer.scherg Rainer.Scherg at t-online.de
Sat Jan 21 22:00:24 CET 2006


Mirko Roller schrieb:
> hy,
> 
> iam trying to parse the EIT from an sat-transponder (dvb-s).
> 
> I managed to get the pid 0x12 = EIT out of the TS, and iam now analysing it.
> But iam suffering from the very bad etsi docu. I do not understand some parts.
> 
> The first thing i do not understand, why is the descriptor data so bad 
> readable ? Do i need some extra etsi doc to understand the descriptor data ?

What ETSI doc are you using?
For a complete understanding you need to read the following standards:
   ISO 13818-1
   ETSI EN 300468
   and for some special stuff and descriptors there are some other
   ETSI docs.

> 
> Second thing, the doc is saying something, that it is possible to have
> sections, sub_sections, and tables. If i do understand it right, the
> eit.section_number gives the number of the current section. And should start 
> with 0, bit here it starts with 152. 

Of course, the broadcaster doesn't know, when you are starting to read 
the data. 8). So the complete data is split in several section packets 
(numbered from zero to "last_section_number"). You have to reconstuct
sequence and versions. Data are send periodically in a kind of a data 
carousel (don't confuse with DSM-CC)...

> 
> Also, the complete Table is 184 bytes long, but saying that this section is 
> only 70bytes long. Where does the second section (sub_section?) start ?

Where did you get the 184 as table size?
Looks like the transport stream container packet size.

> 
> You see iam a little lost, can someone explain me some things ?
> 

Maybe http://dvbsnoop.sourceforge.net will be some help for you in 
understanding DVB and MPEG streams...

rasc





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