1

I attached two webcams to RaspberryPi 3B+ using USB power hub. But when I wrote ls -la /dev/video* in Terminal, output shows many video devices as shown below:

crw-rw----+ 1 root video 81, 0 Jun  7 12:28 /dev/video0
crw-rw----+ 1 root video 81, 1 Jun  7 12:28 /dev/video1
crw-rw----+ 1 root video 81, 2 Jun  7 12:28 /dev/video10
crw-rw----+ 1 root video 81, 5 Jun  7 12:28 /dev/video11
crw-rw----+ 1 root video 81, 6 Jun  7 12:28 /dev/video12
crw-rw----+ 1 root video 81, 3 Jun  7 12:28 /dev/video2
crw-rw----+ 1 root video 81, 4 Jun  7 12:28 /dev/video3

I think it should show two video devices only. Why it is showing multiple video devices? What is the meaning of video10 etc? While working, using video0 and video2, camera get started. Why not camera get started with video1?

3
  • I don't know the answer to your question, BUT why don't you try to investigate it yourself? Try with no cameras, 1 camera etc. On my Pi3B+ I have no camera but /dev/video10 /dev/video11 /dev/video12
    – Milliways
    Commented Jun 11, 2019 at 5:12
  • I already checked with No cameras and it shows crw-rw----+ 1 root video 81, 0 Jun 11 10:18 /dev/video10 crw-rw----+ 1 root video 81, 1 Jun 11 10:18 /dev/video11 crw-rw----+ 1 root video 81, 2 Jun 11 10:18 /dev/video12 Commented Jun 11, 2019 at 5:20
  • It's remotely possible that your cameras are designed to expose themselves as more than one interface, and that your baseline case has some other driver loaded to appear as a camera. Use v4l2-ctl -D --list-formats on each device to diagnose.
    – jdonald
    Commented Jul 20, 2019 at 2:06

1 Answer 1

1

They represent hardware encoders/decoders/pixel converters. You can observe their details with command

v4l2-ctl --all --device /dev/video*

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.