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Why does the frame rate differ after deinterlacing? Isn't interlaced TV 50 or 60 half frames per second?

• samplatt 7y ago
  At a guess, high-latency phosphor changes on old CRT TV's made the video look smoother, even if it was blurrier.
• LocalH 7y ago
  Probably bad deinterlacing somewhere along the way. For too long, half-rate deinterlacing (60i > 30p) has been common. That's starting to change with 60p support on major distribution platforms, but in the piracy scene half-rate deinterlacing is still common for many types of content.
• proverbialbunny 7y ago
  It's a complex subject. Most NTSC interlacing is what you call 3:2 interlacing. When deinterlacing this kind of interlaced content, the best method is a 3:2 pulldown which converts the frames back to the original frames, or almost all of them, that is. There is a few frames lost in this process. Eg, 30fps interlaced then deinterlaced turns into 29.97 fps. 24 fps turns into 23.976 fps. This introduces a sort of stutter that true progressive content does not have. Also, in the 90s most anime, for example, was 24 fps, where modern day anime is 30fps or higher. This difference is noticeable as well.
  • pedrocr 7y ago
    That's really interesting, thanks. Isn't it possible to fix the stutter by transforming the video into 60fps exactly with frame interpolation? Wouldn't that simulate what an old CRT would end up doing and look better? Or maybe just fudge the timestamps to go to 30fps as the very slight speedup will not be noticeable?