[mythtv] Determining which card live tv is using

[Worldnet]

I have a backend which has 4 capture cards and several remote frontends. I
would like to be able to send remote commands to the satalite boxes
feeding the cards for various reasons (box gets stuck in a menu or channel
not available screen etc)from the remote frontend. I have an idea of how
to do this but I cannot find a way to reliably determine which capture
card I am watching. I thought I could query tvchain but on closer
inspection it only tells me which input is being used on the card, not
which capture card is being used. Is there a way to relate a tvchain
record to a card? I would like to do this without altering the myth and
breaking my ability to install new versions.

Thanks