Only 2 out of 3 USB cams work at once.

[zccopwrx]

Really odd here, I have 2 QuickCam CTX's and one QuickCam 4000. I can only get 2/3 working at once, any combination of them, but NEVER all 3 at once.

www-data 5161 4.2 1.1 126148 12288 ? S 09:56 0:11 /usr/bin/zmc -d /dev/video0
www-data 5591 0.1 1.1 126144 11764 ? S 09:58 0:00 /usr/bin/zmc -d /dev/video1
www-data 5662 8.0 0.7 126208 7764 ? S 09:59 0:08 /usr/bin/zmc -d /dev/video2


Only 2 of the 3 processes actually do anything..

Any suggestions??

Ubuntu 7, ZM 1.22.3, using gspca drivers.

shmmax/all all over 500MB

Thanks!

[zccopwrx]

Oh and theres absolutely nothing in any log that suggests anything bad is happening, the zmc process runs, and simply doesnt get anything, I think its getting "LOSS OF SIGNAL". Because as soon as I strace it, it dies. then zmwatch restarts it on a new pid.

If I unplug one of the working cams, then restart ZM, then the previously NOT working cam would start working..

Is this a USB limitation?

[cordel]

Yes it is a usb limitation, If your mainboard has a couple different hubs on it (most today do ones located on back plus a header on the board) you can try butting your third cam on the second hub.

[zccopwrx]

Thanks for your input

I tried that, the mobo has 2 onboards on the back, and a header connected to two in the front, so I've tried a few combos and no luck so far.

Would using a powered USB hub have any effect? I wonder if its a pure USB bandwidth limitation or a power limitation. Because all 3 devices show up in lsusb, but the LAST one that was plugged in does no actually capture. When I strace it, I see a error signal saying :
send(2, "<139>Aug 4 20:58:42 zmc_dvideo2"..., 107, MSG_NOSIGNAL) = 107

[cordel]

I remember reading some where That a hub would give a usb cam better performance but that was back in the 1.1 days and I don't remember the particulars to the article.