Depends a lot on what card you have. Many of the "security system in a box" devices that turn up on eBay (etc.) use a chipset that can only capture from one input at a time. They are usually bundled with software that drives the card thru a fast "round-robin" of the inputs (repeatedly) to create the illusion of capturing 4 inputs at once. Sort of a "software multiplexer". Most of these cards have a single Rockwell (aka Conexant) BT878 chip onboard. If you have that sort of card, it isn't going to work. But if it has 4 BT878's onboard perhaps there is a way...

Please post whatever details you can about your card. If nothing else, get the numbers off the main chip - that might be enough to figure this out from. I'll check back here when I go home tonight.

EDIT to add: here's a link to pictures of the kind of card that won't work. Note there's only on digitizer/compressor chip. *** LINK ***

Based on my reading of the BT878 datasheet ( ** LINK ** ), the chip is using a 1 of 4 input multiplexor. IOW it captures from one video input at a time, and commands from software tell it which input it should be using. See page 107 of the datasheet (which is page 119 of the PDF file). This just reconfirms my belief that the various "4 cams at once" security softwares are just driving the multiplexer in a fast round-robin of inputs - thus not truly capturing from 4 cams at once but actually "time-sharing" one BT878 between 4 cam inputs.

So, I expect what you are going to find is that your card turns up in AbelCam (and in Windows device manager) as ONE video device (the chip), not FOUR devices (the inputs/cams). That isn't gonna work for what you were wanting to do. If you feel brave, there is probably a third-party driver for BT878 cards out there somewhere that implements the multiplexing round-robin at the kernal level and presents 4 "virtual" video devices to the WDM. Maybe.

Also have a look at this card ( ** LINK ** ) which clearly says it CAN deliver 4 cams simultaneously. By the looks of the picture I'd say it has 4 BT878s on-board plus a fifth large chip for something or another.