[linux-dvb] DVB file formats

[Andrew de Quincey]

> [Presets]
> Number=ONID:TSID:SID
>
> e.g.
>
> 1=1:1101:28106
>
> Now this could definitely be more sophisticated, e.g. to allow several
> presets groups. A simple extension would be:
>
> [Presets.Default]
> ...
>
> [Presets.Sports]
> ...
>
> [Presets.News]
> ...
>
> This could even be taken several levels deep:
>
> [Presets.Movies.Action]
> ...
>
> [Presets.Movies.Horror]
> ...

I can't think of a better/clearer structure than this - I've put an example up 
on the wiki: 

http://www.linuxtv.org/wiki/index.php/File_Format_Comparison#Ideas_for_a_presets_file_format


Now however, the multiplex differentiators are the problem (for distinguishing 
between transponders with the same IDs). Does anyone have any suggestions as 
to good numbers to use?

Obviously they have to be based on the frequency somehow, but they also have 
to take into account tuning varaiations between people's systems (e.g. 
different LNB drifts).

The first thing that springs to my mind is something like the following:

DVBS: ((frequency / (symbolrate/1000)) << 1) | polarisation
DVBT: (frequency / bandwidth)
DVBC: (frequency / symbolrate)
A naive implementation