[mythtv-users] detecting blank screen if video source is turned off

[Michael Lynch]

On 10/11/07, Adam Hirsch <mythtv at quakerporn.com> wrote:
> I asked this once, several years ago, and never found a particularly good
> solution.  Figured I'd try it again.
>
> Every once in a while, our cable box turns itself off.  Since we don't
> watch recordings every day, this occasionally results in several days
> running where Myth will cheerily record entirely blank hours of television.
> This is irritating and significantly drops the WAF, as you may imagine,
> though I blame most of the problem on the cable box.
>
> I tried capturing 10 seconds of video directly off /dev/video0 when the
> video source was showing images and when it was turned off, hoping that the
> two captured files would be different in size, and I could script a nightly
> check and turn the cable box back on.  No luck.
>
> Anyone else had this problem, or have a creative solution?
>
> Adam
>

If you're using an irblaster or some sort of channel changing script,
perhaps you could utilize the discrete power codes somehow?

http://www.hifi-remote.com/ofa/discrete.shtml
http://www.remotecentral.com/cgi-bin/mboard/rc-discrete/list.cgi