Fixing webcam flicker in Linux with udev

I recently got a new Dell XPS 13 (9360) laptop for work and it’s running Fedora pretty much perfectly.

However, when I load up Cheese (or some other webcam program) the video from the webcam flickers. Given that I live in Australia, I had to change the powerline frequency from 60Hz to 50Hz to fix it.

sudo dnf install v4l-utils
v4l2-ctl --set-ctrl power_line_frequency=1

I wanted this to be permanent each time I turned my machine on, so I created a udev rule to handle that.

cat << EOF | sudo tee /etc/udev/rules.d/50-dell-webcam.rules
SUBSYSTEM=="video4linux", \
SUBSYSTEMS=="usb", \
ATTRS{idVendor}=="0c45", \
ATTRS{idProduct}=="670c", \
PROGRAM="/usr/bin/v4l2-ctl --set-ctrl \
power_line_frequency=1 --device /dev/%k", \
SYMLINK+="dell-webcam"
EOF

It’s easy to test. Just turn flicker back on, reload the rules and watch the flicker in Cheese automatically disappear 🙂

v4l2-ctl --set-ctrl power_line_frequency=0
sudo udevadm control --reload-rules && sudo udevadm trigger

Of course I also tested with a reboot.

It’s easy to do with any webcam, just take a look on the USB bus for the vendor and product IDs. For example, here’s a Logitech C930e (which is probably the nicest webcam I’ve ever used, and also works perfectly under Fedora).

lsusb |grep -i webcam
Bus 001 Device 022: ID 046d:0843 Logitech, Inc. Webcam C930e

So you would replace the following in your udev rule:

  • ATTRS{idVendor}==“046d”
  • ATTRS{idProduct}==“0843”
  • SYMLINK+=“c930e”

Note that SYMLINK is not necessary, it just creates an extra /dev entry, such as /dev/c930e, which is useful if you have multiple webcams.

5 thoughts on “Fixing webcam flicker in Linux with udev

  1. Thanks for sharing! I was about to return my LED light, as some of them cause flicker, others don’t.

  2. Awesome post!

    Five years after the original post, this article is still helping people!

    This fixed a problem for me with a C270 webcam being used on a RPi 4B that drives my 3D Printer.

Leave a Reply

Your email address will not be published.