[mythtv] dvb-c scanning problems

Rudy Zijlstra mythtv at grumpydevil.homelinux.org
Fri May 11 23:07:42 UTC 2007

Markus Schulz wrote:
> hello,
> i've some trouble with transponder scans on my dvb-c network.
> My provider broadcasts wrong NIT(-other) data, it comes directly from 
> satelit and therefore is completely wrong for my cable-network.
> Also scanning with a correctely prefilled dtv_multiplex list breaks all 
> channels and destroys the multiplex list (all mutiplexes are updated 
> with wrong [dvb-s] data).
> The multiplexes will be overwritten cause the get_dtv_multiplex() (used 
> inside insert_dtv_multiplex to find existing) method dont respect the 
> modulation parameter for dvb. For users with DVB-c _and_ DVB-s cards 
> this should be fixed too.
> Whats now the best way to solve this? Make it switchable (enable/disable 
> of NIT-processing)? Or better to check if NIT informations are for the 
> same network type what we are scanning and drop the NIT informations if 
> it was for another type? 
> For the latter i've taken a look into SIScan::HandleNIT(), here this 
> could be handled. But i don't know how to detect which 
> network-scan-type is currently running to skip the 
> ChannelUtil::CreateMultiplexes() call if desc.DescriptorTag() was 
> different. 
> HandleNIT seems to be called thru QT-Events, but don't find from which 
> place. Can someone give me a hint?
> Whats the general way for scanning dvb-[cst] with an empty mulitplex 
> list from users-point of view? 
> I think it would be nice to support the transponder lists from dvb-utils 
> package and let the user choose a transponder list based on his region.
Let me guess......

1/ Germany
2/ small private cable network
3/ no affiliation of this network with either KDG, KBW, unity media, ...

create a script to:
a/ modify the TS back to what they need to be (to be applied after each 
b/ scan only 1 TS at a time, and do *not* scan all known TS
c/ delete each unwanted DVB-S TS incorrectly added after each TS scan.

Its how i got my Dutch DVB-C working, where (as usual) NIT-Others is 
used in stead of NIT-Actual.


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