I have a project that I've already made, and it's sole purpose is to black out a TV via a composite cable. The video comes in and is connected to a reed relay in the normally closed position. I have a button connected to the arduino. When I have the system running, the video passes through the relay, uninhabited, to the TV. When I press the button, my code switches the relay and cuts off the feed, and outputs a black NTSC signal.
Now my question is, is there a way to eliminate the relay? Could I have the composite video come into an analog pin, and then pass it out another analog pin?
I wouldnt think the arduino would be capable of doing the a/d & d/a operations fast enough.
Maybe you could instead control a bus switcher (eg How-To: Make a solid-state A/V switcher | Engadget), or do something with a FET.. Im not sure there's any real benefit there over a relay, to be honest.
The bus switcher is interesting. Looks more complicated than a simple relay though. Would I be able to use a MOSFET for this? Something that is normally closed or something.