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

Graham gravety at grahamvoce.com
Wed Dec 21 05:52:41 EST 2005

Nick wrote:

>On 14/12/05, Graham <gravety at grahamvoce.com> wrote:
>>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).
Yes I am aware of this (it is an internal analogue tuner), I just
wondered if there was any way to emulate the MythTV internal method.

>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.
Thanks!  I had considered this a while back as it should give a better
Sky picture too.  The only problem with this method is that the Sky box
is in another room.  Now, there is already an RF cable running round the
house but to achieve this I would need to run a composite lead round as
well and split this into the 2 TV cards.

Apart from that this is a good solution.



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