Originally Posted by kriktsemaj99
Surely 30/60fps video is going to look smoother if passed to the display at its original frame rate. I don't see how you can get smooth video by first converting 30/60fps to 24fps.
You got a Samsung TV with a 120 hz AMP mode? Try a DVD at its native 60 FPS rate and AMP set to anything higher than Clear. You'll get stutter. Lots and lots of stutter
. Now force 24 Hz from the DVD player source (in my case, a computer). Only video frames synced to the current refresh rate will display. AMP will then utilize interpolation of every other frame (something it can't do properly with 60 FPS material because 60 FPS = 1:1 ratio to refresh rate while 24 FPS = 2.5:1, leaving plenty of time to process the video frame), and creates smooth video.
I used to have nothing but stutter with AMP's smoothing, then hearrean (finally) clued me in to forcing 24 Hz mode, which lets AMP perform at its fullest with almost no stutter at all, and very tolerable judder (which can be manipulated in Custom mode for AMP).
The reason this works? There is no conversion from 60 FPS to 24 FPS (reverse 3:2 pulldown). You sacrifice some of the video material, use interpolation on what's left, and end up with smoother video than the original source, with nominal judder (again, this you can manipulate to your liking).
The reason AMP can't smooth 60 FPS video is very simple. At 60 FPS, there is a 1:1 ratio between refresh rate and frame rate. That leaves....drumroll....zero time to process the frame data for interpolation
. What you get is initially smoothed video, then it sort of "glides" at in increasingly unnatural rate (like a crescendo, only visually in terms of speed), and BAM! Video halts, and you get stutter until the TV's processor can re-sync itself with the incoming frame data. At 60 FPS, only Clear works properly as a setting for AMP. This is because AMP interpolates at the following rates:
Clear: Key frame = every sixth frame. Drops 5th frame and injects interpolated frame.
Standard: Key frame = every fourth frame. Drops 3rd frame and injects interpolated frame.
Smooth: Key frame = adjacent frames (back to back). Interpolates frame data and injects new frame between the original two frames. Because of 60 FPS being 1:1 correlation between refresh rate, no room to inject new frame, so AMP must drop every other second
key frame, causing the "hurry up and wait" stutter.