How to record screen in ffmpeg so to compare with original and recorded video with ssim. this looks a simple tasks but when recording ffmpeg is dropping and duplicating frames and so it does not match frame to frame on original video. though duplicate is around 100 and drop is around 0 to 30, I see sometimes ssim gives high score but another time it does not. when i checked there was a delay of few milliseconds which can be hardly seen on naked eye.

Note: In ubuntu with nvidia it works fine, problem is on windows only (intel gpu)