[linux-dvb] DVB file formats

Johannes Stezenbach js at linuxtv.org
Thu Jun 16 10:53:38 CEST 2005


On Thu, Jun 16, 2005 at 03:27:43AM +0100, Andrew de Quincey wrote:
> On Thursday 16 June 2005 01:58, Robert Schlabbach wrote:
> > Why not merge channels (I'd prefer the DVB term "services") and transponder
> > (locator) information in one section then...? Might be better to keep them
> > together anyway.
...
> As for channel->service - if thats the DVB standard, it would make sense to 
> move to that I agree. Its a pity they don't have a standard name to describe 
> the concept of a transponder across all media types though :)

I would prefer "service", too.
How about "multiplex"? Mostly used for dvb-t, but IMHO more generic
than "transponder".

> > Then you have to find a way to satisfactorily reference services. DVB's
> > ONID:TSID:SID may not be sufficient, as e.g. here in Germany, ASTRA
> > satellite transponders are fed into the cable networks with exactly the
> > same ONID:TSID:SID's, so a preset file using only that would not allow
> > selecting whether the service is to be received from cable or from
> > satellite (if both are available)... OTOH, services might move and their
> > ONID:TSID:SID might change, but it will still be the same service. For such
> > cases, referencing the service name would be better, but some service names
> > can be found several times, e.g. I think there are a couple "Bloomberg"'s
> > on ASTRA 19.2°E... Maybe the presets file should contain ONID:TSID:SID
> > _and_ service name (and maybe network and provider name) and even the
> > adapter ID, so that the application can then look for the closest match.
> 
> Duplicate channels on seperate sources are not a problem as each transponder 
> knows what source it is from. But yes, identifying duplicate channels from 
> the _same_ source are a problem you are right. 
> 
> Previously I've used a combination of the frequency, the polarization, the 
> ONID, TSID, and SID in order to uniquely identify a service. Not nice :(

The purpose of the network_id is to differentiate services in this case.

(But you still can't rely on the broadcasters to assign correct/unique ids.)

Johannes




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