[mythtv-users] channel changing/tuning

R. G. Newbury newbury at mandamus.org
Sun Aug 12 23:38:15 UTC 2007

Johan van der kolk wrote:
> Hi, 
> fairly new to linux, and have a little problem.
> Have myth 0.20 running on FC 
> FE and BE are on the same box.
> Myth is not tuning my receivers (a PVR500 and a DVB-s Hauppauge Nexus).
> I have gone through the setup, did the capture card -> input thing, set the
> frequency table to Europe-west, and standard to PAL. Did a channel scan and
> channels are found. Not using a xmltv source for the moment.
> When I start myth (watch live TV) on the PVR 500 it gets stuck at a certain
> frequency and I can not use the up and down to change channel.
> It is not tuned to a proper channel.

That is likely the important clue. Myth notes the last tuned channel and 
attempts to tune to it again, when starting up. If the "last tuned 
channel" is actually impossible to tune, it will not tune, and then will 
not change channels!

The trick is then to change database to a 'proper' channel. The 
following script should do the trick. I call my version 
'start-chan-reset'. You can hardcode the channel and card values, in 
which case only the last three lines are necessary.


echo "Args provided: Channel: "   $Channel "    Card: "     $Card
if [ $1 = abc ];
   echo "You must provide a channel number."
if [ $2 = xyz ];
   echo "Need to give a Card number."

echo 'update cardinput set startchan = '$1' where cardinputid = '$2' > 
mysql -u mythtv -pmythtv mythconverg < /var/tmp/startchanfix
rm -f /var/tmp/startchanfix


> When I switch to the DVB-s card the tuner can never get a lock, although I
> can move through the mythtv channels. It only found channels from one
> transponder though in the setup, but thats ok for now.
> I can use mplayer /dev/video1 to show the PVR500, and I can use ivtv-tune to
> change channels.

This tends to show that it is myth's mysql table which is causing the 

> I can also use Kaffeine as my DVB display/tuner, all works fine.

Harder to know what's wrong here. Likely the same sort of problem. See 
if you can determine the tuning parameters used by Kaffeine and see if 
myth has the same numbers in the tuning setup (Channel Editor in 
mythtv-setup). Although you may have an antenna problem. Myth seems to 
need a stronger signal to lock on, that vlc, or mplayer.


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