[mythtv] DVB-C broken - update FAQ ?

[Janne Grunau]

On Wednesday 25 June 2008 00:36:53 kiu wrote:
>
> there are several bug reports about broken channel scanning for dvb-c
> with some smaller providers.

Not necessarily related to small providers but providers which don't 
follow the DVB standard.

> Could you give a small explanation why it is broken ? We could use
> these information to update the FAQ on the mythtv.org wiki and save
> users like me several hours of scanning transponders, reading bug
> reports, etc.
> This would be a huge step forward in the user point of view.
>
> As far as i understand it, some small providers send bogus data
> inside the dvb-c stream which mythtv doesnt like (because its not
> dvb-c compliant), correct ?

There a too different cases.

Some provider change the modulation of satellite feeds for DVB-C but 
don't modify the dervice information. I think (hope) this should be 
handled gracefully by MythTV. One have to scan each frequency manually 
but there is no way around it.

The other case is a wrong Network Information Table. These providers 
have different regional channel lineups burt generate the SI in a 
central place. They transmit for each region one NIT all the time. The 
DVB standard has a flag to indicate whether a NIT is for the actual 
network or for an other network. This information is not correct for 
all but one of the regional networks. One has to know the network id to 
get the correct network information table.

> Why is w_scan/dvbscan/czap working without any problems then ?

They aren't trusting the NIT.

> PS: How do you define small providers ? Eg the provider for Munich
> (Population: 1.3M) is broken :)

as I said above, not necessarily related to small providers


Janne