[linux-dvb] Re: scan file for de-Kabel_BW

Christoph Pfister christophpfister at gmail.com
Sun Apr 15 11:57:55 CEST 2007


Hi,

Am Samstag, 14. April 2007 06:31 schrieb Dirk Ritter:
> Hello again!
>
> Am 2007.04.13 15:51 schrieb(en) Christoph Pfister:
> > You can omit those frequencies scan is able to
> > find by analyzing the stream.
>
> Indeed. And it seems to have the ability to
> tune into known frequencies, so it is a lot
> more clever than I thought.

This procedure is specified by the dvb standard.

> > This results in a smaller file (and less tuning
> > errors in case transponders are removed), but
> > still all channels are available.
>
> Works for scan using just a single frequency.
> I wonder why you cannot just do away with those
> scanfiles altogether, poke around and use known
> frequencies for known ITU channel names instead
> - as is the case for the analog TV PVR tuner
> application:
>
> http://ivtvdriver.org/viewcvs/ivtv/trunk/utils/ivtv-tune/frequencies.c?view
>=markup
>
> (That needs the region you live in and things
> like "S23", or "K50" as input for tuning, but
> a shell script will do in order to translate
> your actual TV station names into ITU channel
> names. No big deal. It is analog TV, so some
> level of manual intervention, i.e. the particular
> channel name -> TV station name mapping needs
> to be dealt with.)
>
> > Do I understand you correctly and for example
> > the following scan file would still find the
> > complete set of channels?
> >
> > C 113000000 6900000 NONE QAM64
> > C 418000000 6900000 NONE QAM256
> > C 466000000 6900000 NONE QAM64
>
> The following will do fine:
>
> C 113000000 6900000 NONE QAM64
>
> One measly line. :-)
>
> The drawback:
> With this we now depend on the cleverness
> of the tool used for the scan.

The scan apps are supposed to support that. The problem in practice is morely 
that the information transmitted by the broadcaster isn't correct or 
complete; but doesn't seem to be the case here ...

> > If yes, I'll include those (as there's no sense
> > in having more initial tuning settings than needed;
> > three transponders just seem a good number to me
> > if any of them becomes invalid).
>
> True. If the initial frequency is not usable,
> then the scanfile will become useless as well.
>
> May I still suggest to:
>
> a) have only one such scanfile for Kabel BW,
>     using the lowest frequency all three Kabel
>     BW network regions have in common
> b) have only one initial line for scanning

Agreed, will commit that soon.

> c) document it somewhere how complete channel
>     listings are just a waste of time as well
>     as error-prone

Hmm ... maybe an entry in the dvb wiki? Other than that I can't see a place 
for this (except me complaining on the mailing list if you have too much 
freqs ;)

> (Reflected in the attachment. Comments that
> reflect suggestion c) in German language.)
>
> The only catch I found thus far:
>
> Using some random listing (I tried "de-iesy")
> produces less channels, so not everything is
> utterly meaningless. Probably a line with the
> wrong modulation setting will render the
> particular frequency it tries to define useless,
> effectively depriving you of said frequency
> when it will be skipped as invalid due to
> misconfiguration?

Depends on the scan utility - dunno.

> One good reason for the single line approach,
> it seems... ;-)
>
> > If no, I'll complete them with the necessary
> > entries ...
>
> Actually it was my impression that scan and
> Kaffeine only use what is provided because
> most scan files seem to have complete lists,
> but if I run a Kaffeine scan using only one
> single initial frequency, then all channels
> will show, i.e. I still arrive at 393 TV and
> 225 Radio stations for Kabel BW, using just
> a single frequency definition.
>
> It is so simple! Plain wonderful! :-)
>
> Kind Regards,
> Dirk

Great that this is solved now and thanks a lot for your answers :)

Christoph



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