I have been looking at capture cards and am having trouble figuring out how to figure out the bandwidth they put into the computer.

I have figured out that each camera has a different type of encoding and data transfer rate which goes up as the resolution and framerate goes up. This signal from the camera goes to a capture card and into the computer to be used by VMIX.

I have also figured out that most high end cards convert the input signal they receive from the camerea into (often) a different size (and type?) of file often in accordance with options chosen by the user (bigger, smaller etc).

I am wondering: What type of signal does the converter box actually send to the computer. Is it a dramatically reduced size due to some fancy codec? It is most certainly very different from what comes out of the camera or it could just go into the computer without the card.

question 2....

Is the size of the signal which the computer needs to swallow dependent on the settings put in by the user and applied by the fancy converter device. In other words, can I make is smaller by having the capture card convert it to a smaller resolution for example?

I am sure it is much simpler that I am making it.

I do appreciate any and all help.

The real question ...

I quess the bottom line is I am having a hard time figuring out what goes out of the capture card to be used by VMIX????

Thank you all.