usb-camera

dmesg | grep -i "camera\|video"

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Based on the output of v4l2-ctl, your webcam device (/dev/video3 or /dev/video4) is successfully recognized by the system and uses the uvcvideo driver. Here are some key points and steps to troubleshoot why it may not be working with ffplay or similar applications:

Analysis

1. Capabilities:

   • /dev/video3 and /dev/video4 support video capture and streaming. However, only /dev/video3 has the “Video Capture” format enabled.
   • The default resolution is 640x360 with the pixel format YUYV.

2. Driver Version:

   • The driver version is 6.10.6, which is modern and likely compatible with most Linux distributions.

3. Format:

   • The webcam supports the YUYV pixel format. Ensure ffplay is configured to handle this format.

4. Error in ffplay:

   • The error "Inappropriate ioctl for device" or "Input/output error" usually indicates a mismatch in the requested configuration or permissions.

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Troubleshooting Steps

1. Verify Device Access:

   • Confirm that /dev/video3 or /dev/video4 is accessible:

     ls -l /dev/video3 /dev/video4

     Ensure the permissions are set to crw-rw-rw-. If not, adjust them:

     sudo chmod 666 /dev/video3 /dev/video4

2. Test Using v4l2-ctl:

   • Capture a single frame to verify the camera is operational:

     v4l2-ctl -d /dev/video3 --stream-mmap=3 --stream-count=1 --stream-to=test.yuyv

     Convert the file to an image using ffmpeg:

     ffmpeg -f rawvideo -pix_fmt yuyv422 -s 640x360 -i test.yuyv output.jpg

3. Specify the Pixel Format in ffplay:

   • Try running ffplay with explicit parameters:

     ffplay -f v4l2 -input_format yuyv422 -video_size 640x360 /dev/video3

4. Check for Conflicting Processes:

   • Ensure no other processes are using the webcam:

     fuser /dev/video3

5. Check System Logs:

   • Inspect the system logs for relevant errors when accessing the device:

     dmesg | grep video

6. Test with Other Tools:

   • Use another tool like cheese or guvcview to test the webcam:

     sudo apt install cheese
     cheese

7. Update Drivers:

   • If the issue persists, update the uvcvideo module:

     sudo modprobe -r uvcvideo
     sudo modprobe uvcvideo

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