Most decent camera controllers have tally outputs. Is there any way to use these tally outputs to keep the camera being controlled with the camera being used for preview in vMix (vMix would only respond to tally state changes)? If that would work, it would also be nice to have a one tally output for triggering preview transition to output.

I know you could do this with MIDI but that requires two button presses. It would be awesome if these two devices could stay in sync.