Comment by swiftcoder
1 day ago
> I’m pretty sure that’s because the lights are actually flickering
They are, but the camera stack should be detecting and compensating for that - it's pretty easy to detect, since it should be a fixed 50/60Hz depending on geographic location. You typically have to implement this filtering on all manner of light sensors.
It’s not just about matching the frequency but also the phase.
This is easier when your lights are all in phase and also in a single frequency, but you might also have bulbs that are at different frequencies (120 vs 60) or electric hookups that go out of phase.
It’s a very tricky problem to solve and to the best of my knowledge, nobody truly has. Film lights do clever and expensive tricks to match phase but that’s not feasible in a domestic setup.
Um. 240 is a multiple of 60.
Yes, so you either get a strobe on/strobe off every two frames if you're in 60 Hz country, or a slower crawling flicker in 50 Hz land. Migraine-inducing either way. Also, your phone won't shutter at exactly 60.00/50.00 Hz (mains freq. is pretty stable, usually stable to at least the first decimal) so you'll see a jittered, jumpy phase drift on top of that.
Yep, and this breaks all sorts of computer vision setups. We had to compensate for it on the cameras that track the Oculus controllers, since folks are often playing under indoor lighting