在 Linux 中禁用网络摄像头的自动对焦

Question

I'm working in embebed system in the beagleboard. The source code is in Python, but I import libraries from OpenCV to do image processing. Actually, I'm using the webcam Logitech c910, it's a excellent camera but it has autofocus. I would like to know if I can disable the autofocus from Python or any program in Linux?

Answer 1

Use program v4l2-ctl from your shell to control hardware settings on your webcam. To turn off autofocus just do:

v4l2-ctl -c focus_auto=0

You can list all possible controls with:

v4l2-ctl -l

The commands default to your first Video4Linux device, ie /dev/video0 . If you got more than one webcam plugged in, use -d switch to select your target device.

---

Installing v4l-utils

Easiest way to install the utility is using your package manager, eg on Ubuntu or other Debian-based systems try:

apt-get install v4l-utils

or on Fedora, CentOS and other RPM-based distros use:

yum install v4l-utils

Answer 2

You can also do it in Linux with:

cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_AUTOFOCUS, 0)

For some people this doesn't work in Windows (see Disable webcam's autofocus in Windows using opencv-python ). In my system it does (ubuntu 14.04, V4L 2.0.2, opencv 3.4.3 ,logitech c922).

Answer 3

In case anyone finds is useful, I've come up with a small snippet that can be added to your .bashrc . It will detect which of your webcams has autofocus and disable it. I'm using this with a Microsoft LifeCam HD-6000 that has a flawed autofocus system.

Prerequisite: v4l-utils

# Get a space-separated list of all the video devices available
webcams=$(ls -pd /dev/* | grep video | tr '\n' ' ')
for webcam in $webcams; do
  # Check if the tested video device features autofocus
  no_autofocus=$(v4l2-ctl --device=$webcam --all | grep focus)
  # If it does, disable it
  if [ -n "${no_autofocus}" ];
  then
      v4l2-ctl --device=$webcam --set-ctrl=focus_auto=0
  fi
done

This snippet does certain assumptions:

• You want to disable autofocus on all the video devices featuring it