Very few things are straight-through wiring adapters. Occasionally you'll find one, but most are format converters, protocol converters, etc., that essentially require it to decode the input, lay out the actual information itself in its own memory, and then re-encode that to send out. The ins and outs of any active device like that can't be reversed.
This also holds true for the special-purpose ports on the computer, TV, etc. Video and audio out are output only, and there's a chance of damaging them if you try to use them as inputs, even accidentally. Video and audio in are input only, and you'll always get nothing (or at least, nothing useful) if you plug one of those into another input.
Most signals in live media are inherently directional. Both physical and in software. Make sure you keep straight which direction they're going. A lot of people get that confused - everything's an input because the cord goes "into" the socket; or they think in terms of where something gets its signal and thus get everything backwards, kinda like sight leaving the eyes instead of light entering them; etc. - and it makes their support a lot harder.
