LED lights are everywhere and nowhere moreso than concerts or other performances. Since they are a common source of flicker when shot with a video camera, it’s something we get asked about fairly regularly.
Other types of stage lights can also be problematic (especially in slow motion), but LED lights are the more common culprit. You can see this clearly in this footage of a band. It’s a slow motion clip shot with an iPhone… which will shoot a few seconds of regular speed video before switching to slo-mo. So the first five seconds are regular speed and the next five are slo-mo:
The regular lights are fine, but there are some LED lights (ones with the multiple lights in a hexagon) that are flickering. This happens in both the regular speed and slow motion video portions of the video. You’ll notice, of course, the flickering is slower in the slo-mo portion. (mixed frame rates can sometimes be a problem as well but not in this case)
Usually this is something Flicker Free can fix pretty easily and does so in this case, but there are a few variables that are present in this video that can sometimes complicate things. It’s a handheld shot (shaky), there are multiple lights, and there are performers (who, luckily, aren’t moving much).
Handheld shot: The camera is moving erratically. This can be a problem for Flicker Free and it’s something the Motion Compensation checkbox was specifically designed to deal with (in addition to the Detect Motion settings). However, in this case, the camera isn’t moving quickly which is where this really becomes a problem. So we can get away with only having Detect Motion on. Also… with stage performances there is also often a lot of movement of the performers. Not a problem here, but if there is a lot of performer movement, it’s likely you’ll really need to turn Motion Compensation on.
Motion Compensation increases the render time, so if you don’t need to turn it on, then it’s best not to. But some footage will only be fixable with it on, so if the default settings aren’t working, turn on Motion Compensation.
As is often the case the default settings, the preset Rolling Bands, works great. This is very common with LED lights as they produce a certain type of flicker that the preset/default works very well on.
Multiple Lights: It’s possible to have multiple lights in the scene that flicker, and do so at different rates. Flicker Free can usually handle this scenario, but sometimes you need to apply two instances of Flicker Free. If you do this, it’s highly recommended not to use Motion Compensation and either turn Detect Motion off or set it to Fast. If you have Motion Compensation on and use two instances of FF, you’ll get exponentially longer render times and you might run out of memory on the GPU causing a crash.
Slow Motion: Slo-mo footage can really slow the flickering down, requiring you to max out Time Radius. Again, this is a setting that can increase render times, so lower values are better if you can get away with them and it fixes the flicker.
This clip was fairly easy. Only one light was an LED light and flickering, So the default settings worked great. If the default settings don’t work there are a few other presets to try: Stage Lights, Projection Screen, etc. But, even if those don’t work right off the bat, hopefully this gives you some tips on how to fix even the most challenging videos of performances.