Any digital A/V people out there?

I'm looking for a device that can take inputs (ethernet, serial, whatever digital stuff they use to hook video up) from cameras or computers in various streaming formats (avi, mpeg4, flv) and allow them to be sent one or more at a time into another computer that will be sending signal to projectors for a live presentation.

Basically, just a hardware unit to receive all these signals and send them into a computer to be processed. Anything like this exist? Software help would be nice, too.

It's for work, BTW, not for my own home theater rig or something.

What do you mean by 'processed'? Why don't you just use the pc connected to the projector to run the video files from other networked computers? Better yet, why can't you just have the files put on that pc ahead of time?

Okay, I kinda figured out I don't need the dumb box. You're right.

Now I just need to find a camera with PTZ and high enough resolution that also outputs MPEG4 or some other nice format. The highest I've found in a quick search does 768 x 576, but that's not enough.

Oh, and it's live video. There are some canned video bits that will go into the presentation, but we'll also need to have videos of the presenters put up on the screens in real-time.