video passthrough

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?

No.

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 http://www.engadget.com/2007/03/13/how-to-make-a-solid-state-a-v-switcher/), 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.

Now my question is, is there a way to eliminate the relay?

Back in the day I made a simple video switcher using an NPN transistor turned on/off by a pc parallel port pin.

If I can use a simple NPN transistor, that would be great. I think I vaguely remember trying that a long time ago and not having success.