Originally Posted by ironchef25
what a 3:2 pull down?
Movies are shot at 24fps.
TV display at 60fps.
So how do you display it? 3:2 pulldown.
The source alternates displaying 3 and 2 frames.
Imagine the movie has frames ABCDEF (this is 1/4 a second 6 frames @ 24fps).
It does a 3:2 pull down and duplicates the frames to
AAABBCCCDDEEEFF (notice it is 3 copies then 2 copies).
The 6 frames @ 24fps (1/4 second) are now output as 15 frames @ 60fps. Movie is still same speed 6 frames @ 24fps = 1/4 second and 15 frames @ 60fps = 1/4 second.
The problem is that not each frame is displayed the same length of time. The A, C, E frames are displayed 3/60 or 1/20 of a second each but the B D F frames are displayed 2/60 or 1/30 of a second each.
This can cause "juddering" where the film jerks ever so slightly due frames being displayed an uneven amount of time. It can be most easily seen in high resolution material with a slow pan across a regular background (tiles or stairs).
The "holy grail" in movie playback would be to display each frame the same number of times. This could be done @ 24fps, 48fps, 72fps, 96fps, or 120fps.
24fps or 48fps is too slow for LCD & Plasma and would flickering and eye strain. 72fps or 96fps would work fine but lead to problems syncing video (30 or 60fps). The magic number is 120fps.
A 120fps panel could:
take 60fps input and display each frame twice AABBCCDDEEFF and get 120Hz.
take a 30fps input and display each frame 4 times AAAABBBBCCCC and get 120Hz.
take a 24fps input and display each frame 5 times AAAAABBBBBCCCCC and get 120Hz.
The ideal display of 24fps content on 120Hz panel would be called 5:5 pulldown because both the even and odd frames are each displayed 5 times.
To display 24fps without 3:2 pulldown you need 4 things:
1) Source with 24fps output.
2) Display that can input 24fps.
3) Display that has proper processing to handle 24fp w/o 3:2 pulldown.
4) Panel displays a a frequency that is a multiple of 24Hz (120Hz would be ideal).