[mythtv-users] Way to change channel (setchannel doesn't work)

Nick knowledgejunkie at gmail.com
Thu Dec 15 12:47:46 EST 2005

On 14/12/05, Graham <gravety at grahamvoce.com> wrote:
> Hi,
> I am hoping someone can help me.  I have written an external channel
> change script that does the following:
> 1) If the freqid passed in is less that 100 it treats it as a
> terrestrial channel and tries to change the channel on the device using
> 'v4lctl -c /dev/video0 setchannel $1'
> 2) Else sets channel to the channel my Sky+ RF is on and executes a
> channel changer command for my Sky control box.
> Trouble is the setchannel doesn't work - I just get a burst of white
> then snow!
> It works fine through MythTV if I remove the external channel change
> command (through setup).  If I try and use xawtv it moans about DGA -
> though I did get it working with the '-remote' option but you still
> couldn't change channels using setchannel.
> I don't know what command MythTV uses to change the channel (as it
> works!) any ideas? - Thanks.

If using an internal tuner (i.e. on an analogue TV card or DVB card),
it is taken care of internally. If using an external tuner, it will
use whatever channel change script you tell it to use (defined in
capture card setup).

The 'normal' way of setting this up is to define 2 separate video
sources (e.g. Terrestrial, Sky) and then attach these to the tuner and
direct inputs for your capture cards. You can then give preference to
the terrestrial channels, and provide a channel change script just for
the Sky source. This should negate the need to code more complicated
if/else channel change scripts and keep things much simpler in terms
of maintenance.


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