[mythtv-users] DVB-C problems

R. G. Newbury newbury at mandamus.org
Wed Jan 3 22:21:21 UTC 2007

Rudy Zijlstra wrote:
> Hi,
> I've been trying to get my DVB-C card working, or rather, to get MythTv 
> working with my cable operator. This means working around the assumption 
> on Myth that all cable operators are fully standards compliant. Or 
> rather, the assumption that all cable operators use DVB-C in the same 
> manner. One of the assumptions here is that the NIT-Actual will describe 
> the actual network layout. On DVB-C it is very common though, that 
> several NIT-Other are present, which each describe the network layout 
> for a particular geographical area. STB for these operators will present 
> the user with a network-id choice, and the user has to type in the 
> network id. The STB then searches for the NIT-Other with this 
> network-id, and installs from there.
> This goes against the MythTv assumptions.
> I've tried to work around this by manual scanning, and taken the 
> following steps:
> - determine the frequencies used on my cable (dvbsnoop of frequency, and 
> manual analysis of of relevant NIT-Other(s).
> - enter found frequencies into dtv_multiplex
> - let mythtv-setup perform scan of transports
> - edit found channels to refer to correct transport stream instead of to 
> incorrectly assumed transports from NIT-Actual
> - delelete transports from NIT-Actual from dtv_multiplex, so they do not 
> clutter the table (and cause confusion for me).
> End result is that it still does not work, because siscanner will work 
> from the NIT, and takes the NIT-Actual (judging from output from "-v 
> channel".
> As i am no coder, i would like pointers to continue this. I would very 
> much like to be able to use my DVB-C card to record.

You don't say what hardware you are using and what other problems have 
forced you to take this route.

What go you get when you do a channel scan from the second page of Input 
Connections (in mythtv-setup) with the 'Unencrypted channels only' box 
That should get you a scan of every available digital stream which your 
cable co sends down the wire...You may only want 30 out of the 450, but 
they are all there..Then run mythfilldatabase (which will put garbage 
into the junk channels). Then use Live TV to check the channels. You can 
use 'e' to see the channel information on channels you can actually tune.

Deleting channels is a bit of a pain. You have to go back into 
mythtv-setup, OR, run mysql in a console and do a 'delete from channel 
where channum = '84#2';' (or whatever the channel is)...(Or check all of 
the 84#x channels and delete using the mplexid). And checking the 
channels will undoubtedly cause some lockups. Run the frontend in a 
window, smaller than your screen space, leave the mouse on the close (x) 
box at the top right, and use Alt-Tab to change windows, if you are 
using a console window for mysql.


More information about the mythtv-users mailing list