From WaseemCh:
could there be another way? maybe 4 usb devices?
Not quite sure what you mean...
If you had 4 analog to USB video devices, AbelCam would see that as 4 distinctly separate cams. For that matter if you had 4 single-input PCI cards AbelCam would see them as 4 cams.
On my AbelCam system I have 3 PCI analog video input cards (about US$45 each) and several Logitech USB webcams. Everything works together fine - AbelCam sees each one as a separate device. My analog PCI cards are "K-World", from Taiwan I think. In addition to analog input (BNC and RCA options) there are also TV tuners on the cards, which sounds like something you don't need.
I also have a K-World gadget that converts analog video to USB. It works fine but its driver eats quite a lot of CPU cycles. I'm not using it right now on my AbelCam system, mainly because I'm running a 10 cam system and with that many cams streaming every little bit of CPU load matters.
I'm not necessarily in love with K-World
. It seems to be okay, and it is the "cheap brand" that my local store carries. I'm sure there are plenty of other equivalent brands out there (probably all the same design, from the same Chinese factory).
http://global.kworld-global.com
Edited to add: Actually, I just found the same PCI cards I'm using for US$31 here:
http://www.xpcgear.com/kwltv7134.html
Note that the video input is RCA connector, not BNC, so you'll probably need to buy a $2.00 adapter.