Your USB webcam bands under mains lighting, and it forgets the fix every time you plug it in. This puts the setting back, on every reconnect.
✅ This is for you if an external USB webcam ripples or bands under mains-powered lighting, and the banding comes back every time you reconnect it. Cameras ship set to 60 Hz, so they are wrong out of the box anywhere on a 50 Hz supply: the UK, Europe, most of Asia, Africa, Australia, most of South America.
❌ This is not for you if it is the built-in camera on a MacBook. Those are not USB and expose no UVC control, so nothing here can reach them, and neither can any similar tool.
brew install andrew-hill/tap/unflicker
unflicker installReplug the camera. That is the setup. Building from source needs the Xcode command line tools; there is nothing else to install and nothing to configure.
Webcams have a power-line-frequency setting that matches exposure to your
mains supply, and they band when it is wrong. macOS exposes it nowhere: no System
Settings pane, no defaults key, no API. Worse, reconnecting a camera resets it
along with brightness, white balance and the rest, so setting it once does not hold.
A camera inside a monitor re-enumerates whenever the display link drops, so powering the
monitor off is enough to lose it.
No daemon, no menu bar item, no timer. macOS starts unflicker when a USB device attaches, it checks whether your camera needs the setting put back, and it quits. The same happens at login for anything already plugged in.