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In case anyone else is looking for the answer for a similar problem. usb_cam is great when it works but is terrible for debugging. In essence you need to debug the camera using system tools (lsusb to see if the camera is attached, dmesg | grep -i USB to see if there are any USB errors). Then see if any other program is able to use the camera (and not blocking it) and try to verify config parameters. In my case the error was -11 and there were no log files! The reason was that device ID had changed. While previously the camera was /device/video0 then somehow it had become /device/video2. You can check the ID using v4l2-ctl --list-devices. Changing the video_device parameter to a new value in a launch file did the trick.

In case anyone else is looking for the answer for a similar problem. usb_cam is great when it works but is terrible for debugging. In essence you need to debug the camera using system tools (lsusb to see if the camera is attached, dmesg | grep -i USB to see if there are any USB errors). Then see if any other program is able to use the camera (and not blocking it) and try to verify config parameters. In my case the error was -11 and there were no log files! The reason was that device ID had changed. While previously the camera was /device/video0 then somehow it had become /device/video2. .

You can check the ID using v4l2-ctl --list-devices. Changing the video_device parameter to a new value in a launch file did the trick.

Also, I was using Ubuntu 20.04 and Noetic but the issue probably is not version dependent.

In case anyone else is looking for the answer for a similar problem. usb_cam is great when it works but is terrible for debugging. In essence you need to debug the camera using system tools (lsusb to see if the camera is attached, dmesg | grep -i USB to see if there are any USB errors). Then see if any other program is able to use the camera (and not blocking it) and try to verify config parameters. parameters.

In my case the error was -11 and there were no log files! The reason was that device ID had changed. While previously the camera was /device/video0 then somehow it had become /device/video2.

. You can check the ID using v4l2-ctl --list-devices. Changing the video_device parameter to a new value in a launch file did the trick.

Also, I was using Ubuntu 20.04 and Noetic but the issue probably is not version dependent.