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I had some capture issue in OBS, where during certain parts of my screen capture some windows flicker.

Here's a sample of the affected footage:

I think this should be at least to some degree correctable algorithmically, but I don't know the tools to implement that.

Basically for every pixel in the video stream I'd have to do this:

# we need to compare the same pixel in three consecutive frames

A = pixels[x,y, current_frame]
B = pixels[x,y, current_frame + 1]
C = pixels[x,y, current_frame + 2]

# if two border pixel values are identical, but the middle one is different - we assume that to be a flicker, so we replace the middle frame with the first one
if A == C and B != A:
   pixels[x,y, current_frame + 1] = pixels[x,y, current_frame]

# let's move onto the next frame
current_frame += 1

I wonder if this is possible to do with GLSL - I don't know if it has access to frame history...

Are there any (preferably free, open-source and running on Linux) tools that could do this?

  • ffmpeg could be made to do this, although your proposed method would not get rid of all flicker. If there's some screen activity/anim then A != C, and won't alter B even when B is defective. Also, in one or two cases, the tear lasts for more than one frame. – Gyan Aug 11 at 20:31
  • I've implemented this using Blender's Compositor - it seemed to help a bit for short clips, but I had trouble with A/V sync so I dropped the idea. I'm including this in an answer however in case anyone wants to try this in their own projects. I'd like to know more about the ffmpeg-based solution though, as that might be much faster to process (the Blender implementation was rather slow). – unfa Aug 15 at 20:44
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The propose algorithm can be implemented using Blender's Compositor.

Here's a working project file: https://is.gd/TeA4xC

You need to supply the same video file as input to three input nodes - each with a specified frame offset.

This is capable of removing flickers that last no longer than 1 frame.

I tried using this for my footage, but I had issues with A/V sync after remuxingthe result with the original audio, so I dropped the idea.

Here's how the example clip looks like after being processed with this file:

You can tell the flicker is much less pronounced. There are some artifacts, but they are way less distracting.

Hopefully someone will find this useful - I ultimately didn't :/

Enjoy.

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