I recently filmed some content of a thin line of a projected image. The video footage is flickering a little and I am wondering if there's any solution to fix the footage once it's been filmed. I have tried to speed up and slow down the footage and it doesn't seem to change it. Is there any way of editing it out on imovie? Thanks!
tomh's advice to double stack the video layer, reduce opacity by 50% and advance a frame is a great starting point and certainly works well on fluorescent light flicker.
I've just had the same problem with a single chip DLP projector image in shot with the banding looping over about 5 frames. Working in Premiere Pro, I layered the video 3 times, cropped each layer to the projection screen area, reduced each layer to 25% opacity and advanced each layer 1 frame on from the last. I also reduced the brightness on the base layer by 100% (referring to Lumetri Scopes and using my eye to avoid blowing out the slide image). It's a very satisfactory result.
Caveat: If anything crosses the projected image is will look like it has a strobe effect and any animations, video or transitions will have this also, however for a set of static slides you should be fine.
Hope this helps you or anyone else using a search engine to love their quirky issues like i did to find the original post.
I am sure you could do it in another program, like PowerDirector but iMovie is a stretch. If it is random black frame, you may be able to cut those black frames out of the movie so it looks like a completely smooth video.
You would do this by doing frame by frame and when there is a black frame, click the Split button and then find the end of the black, split it again and then delete the part that you separated
It would help a lot if you provided a sample showing the problem. The flicker usually comes from a mismatch between the camera recording the footage and the projector projecting it. If it's a film projector it might be running at 24fps. Most video recorders run at 25, 29.97 or 30fps. But even if you have a matched frame rate you will still get flicker because the camera and projector's clocks are not synchronised - so one will be in the process of closing a frame when the other is still recording a frame, hence the flicker.
You can sometimes reduce the visibility of the flicker by duplicating the video track, moving it forward by one frame, setting the upper track to be semi-transparent, and see if this helps... Example tutorial here (but not for iMovie);
Otherwise you might need to use a more advanced programme like Premiere or After Effects with a de-flicker plugin of some kind - a few below (most are designed for removing flicker in time lapse videos though, not what you have...). Try a demo before you commit to buying these.