[linux-dvb] Re: TS tables doubts

[Andy Coates <andy@bribed.net>]

Nico (sabbi@cs.unibo.it) wrote:
> 
> Hi,
> 
> as far as I understand, in order to find what channels are
> transmitted on a given full TS I have to follow these steps:
> 
> 1) read the PAT to find the list of programs ids
> 2) read the PMT to find the list of ES streams (audio/video/teletext/subs)
> associated to a given program id
> 
> Is it correct?

Sounds about right.

> Now I wonder
> 3) what's the use of NIT and SDT?

SDT is used to basically give you the channel name for a given program ID,
whilst the NIT tells you the frequency/transponder details of this program.

So with PAT/PMT/SDT/NIT you can tune to the right frequency, filter the
correct PIDs, and display in some shape or form the channel name.  Stick
the EIT on there and you should have now/next functionality too.

> 4) reading VLC's demuxer it seems that there's a tables describing the
> type of each elementary stream (e.g. video is M2V, audio is MP2 or AC3
> 2.0 or AC3 5.1); what table is this?

I think thats officially sourced from ISO/IEC 13818-1 (Generic Coding of
Moving Pictures and Associated Audio Systems) - Table 2-36 "Stream Type
Assignments"

But for the information you describe above, thats something different,
since you're actually looking at the characteristics of a type of stream.
I believe that information is also in the same document, but I always refer
to a quick reference I found here:

  http://xhelmboyx.tripod.com/formats/mpeg-layout.txt

HTH,
Andy.



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