Two Firewire Video Inputs doesn't works at the same time...

I finally succeed in getting two iSight firewire camera (they are so expensive ! But fortunately, someone lend me one for a couple of weeks). I want to test a couple of technics using two sources with OpenCV and other great Kineme Plugins (The firewire bus seems to be quickest than USB, that's why i'm getting iSight Camera). That' the good news !

Now the bad news... Quartz Composer doesn't seems grabbing them both ! I use the special AudioVideo Kineme patch instead of the native QC's Video Input to get those two iSight right indexed, but it doesn't works... I only could get one source at a time. I could get the picture of the first or the second iSight but not the picture of the two iSight at the same time. In the Video Input Patch settings i could see that the two iSight are recognized, i could select them, but when i change the settings only one iSight is displayed at a time. I'm working on a MacPro. Could it be a Firewire bus matter ? Could i plug two iSight on the same FireWire bus ? On the MacPro, i use the front side Firewire input and the back side FW input for the second iSight. How could i get two image with those two iSight ? I got this hardware for a few time, and my test period is very short, so thanx for your help !

cwright's picture
Bus limit or QTKit bug

If they're not working, then it's a bug in QTKit, or a limitation of the firewire bus (Apple QuickTime engineers say that it's a limitation of the firewire bus -- you need 2 FW cards to handle 2 cameras.... that doesn't make sense if both cameras are SD though, since that's not a lot of bandwidth...)

I've seen this on a few different setups, and it's my opinion that QTKit/QuickTime have some flaws inside that prevent multiple identical cameras from working reliably -- if anyone has ever had this work on Leopard, please let me know (because that means it really is a FW limitation, and not a QT bug).

smokris's picture
"Known Limitation"

cwright wrote:
it's my opinion that QTKit/QuickTime have some flaws inside that prevent multiple identical cameras from working reliably

This appears to be correct --- according to http://developer.apple.com/qa/qa2004/qa1365.html :

Note: For developers working with DV, simultaneous recording from multiple DV cameras is not supported. The current implementation of the DV Video Digitizer (QuickTime 7.5) only supports a single connection. This is a known limitation.

mfreakz's picture
A chance with two firewire bus ?

Is this a limitation by Firewire bus or a limitation by computer ? Should i try to connect my second iSight (with an adaptor) on the Firewire 800 bus ? One iSight on the FW400 and the other on the FW800 ?

cwright's picture
try it

can't hurt to try. the limitation noted by smokris indicates that it's a limitation of the software (QuickTime), not of the bus or the computer itself.

mfreakz's picture
Arrrg ! Quicktime !

Precisely, if the limitation is about Quicktime, the number of different buses won't change anything not ? Otherwise, do you know a good and cheap USB Webcam (compatible UVB) ?

smokris's picture
One Bus, Multiple Ports

mfreakz wrote:
One iSight on the FW400 and the other on the FW800 ?

Often FW400 and FW800 ports are shared on the same bus, so you need to make sure that your two ports are indeed on separate buses.

In my case, I have a MacBook Pro, and it has FW400 and FW800 ports, but both are on a single IOFirewireController (as evidenced by the "IORegistryExplorer." app included with the developer tools).