I'm trying to connect and use 4 USB webcams at the same time and I've run into a lot of trouble, but I'm not really sure what's causing it. Here's what I've found. I don't seem to have a problem running more then one of the same type of cam. I have two Logitech C910 (which look amazing!) and I they just show up as Logitech and Logitech #2. I can plug all four cameras in, and configure them in the Capture section to be Cams 1 -4, including being able to preview them. Here's where I hit the problem. On my 2010 iMac, i can turn on the first two cams, at the same time, without a problem. But as soon as I turn on the third, it shows black, and the two cams that were working freeze. And as soon as I turn off the 3rd cam, everything works again.
So I tried running them on my Mac Pro which has the same OS (10.6.8) and drivers. This time, I can only turn on one cam. When I turn on the second, it freezes.
I've also tried running two cams in modul8 and then turning on the third in ichat or QC, and the same thing happens. I've tried to run them all in Quartz Composer. Same thing. It's almost like the USB pipe is overloading or it doesn't have enough power. I've tried running the cams off powered USB hubs (one cam per hub) and I still have the same problem, so I don't think it's a power issue.
I've tried running three different cams. I've tried running three of the same cams. I've tried running two different cams and a Videoglide/easycap. Regardless what USB devices are hooked up, or which apps I'm using to access them, it's the same. I can run two on my iMac, or one one my Mac Pro, and that's it.
The best I can do is run two Logitech C910's through USB on my iMac, and the built in iSight cam. When I do that I can have all three cams on at once.
Does anyone know what's going on here? Does each USB port have 480mbps or do they all share the same pipe that can get overloaded? Do you think installing a PCIe USB card for each cam will fix it?