Unable to open video device

Question

Hi,

Last night, my webcam stopped recording; everything was working well. If I have a look via port 8081 I see a grey image with the text "Unable to open video device since 21 May 05:06:31".

As you can see in my SYSLOG, the cam is losing connection with the PC. My cam was on /dev/video0. Now I have found it back on /dev/video1.

In motion.conf I have changed video0 to video1 and it is working again. But how is it possible that this device has changed?

Thanks.

SYSLOG
May 21 05:06:31 webcam kernel: [23943.541344] uvcvideo: Non-zero status (-84) in status completion handler.
May 21 05:06:31 webcam kernel: [23943.576088] hub 1-0:1.0: port 2 disabled by hub (EMI?), re-enabling...
May 21 05:06:31 webcam kernel: [23943.576099] usb 1-2: USB disconnect, address 3
May 21 05:06:31 webcam kernel: [23943.816168] usb 1-2: new full speed USB device using uhci_hcd and address 4
May 21 05:06:31 webcam motion: [1] v4l2_next: VIDIOC_QBUF: No such device
May 21 05:06:31 webcam motion: [1] Video device fatal error - Closing video device
May 21 05:06:31 webcam motion: [1] Closing video device /dev/video0
May 21 05:06:31 webcam kernel: [23943.974590] usb 1-2: configuration #1 chosen from 1 choice
May 21 05:06:31 webcam kernel: [23943.977489] uvcvideo: Found UVC 1.00 device USB 2.0 PC Camera (058f:3820)
May 21 05:06:31 webcam kernel: [23943.980829] input: USB 2.0 PC Camera as /devices/pci0000:00/0000:00:1f.2/usb1/1-2/1-2:1.0/input/input8
May 21 05:06:40 webcam motion: [1] Retrying until successful connection with camera
May 21 05:06:40 webcam motion: [1] Failed to open video device /dev/video0: No such file or directory

Environment

Motion version:	3.2.11
ffmpeg version:	0.5-svn17737+3:0.svn20090303-1ubuntu6
Libraries:	ffmpeg
Server OS:	Ubuntu 9.04 32bit, kernel 2.6.28-11-generic

-- KrisLowet - 21 May 2009

Answer

This is not a motion question really - I had a similar problem using USB cameras with cheap cat5 usb extenders disappearing and reappearing which was a hardware, not a software problem. The solution was to write a script that would listen to hal events and kill and start motion whenever a new video device appeared.

Either try a similar hack or maybe speak to the webcam driver developers?