Difference between revisions of "Talk:Video Playback Slightly Too Fast"
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Revision as of 18:48, 15 March 2013
PAL-Speedup - Technical background
Movies and many television series are shot on film that runs at 24 frames per second. That's also the framerate at which movies are projected in movie theaters. If you'd like to convert that movie to television you have a problem, because regular television sets don't run at 24Hz (= frames per second).
This is how the Americans solve that problem:
The video standard in american television is NTSC. NTSC runs at 60 Hz. To make 60 Hz from 24 fps, you double the first frame, triple the second frame, double the third frame, triple the fourth frame and so forth. Now 12 of the original 24 frames in one second are doubled (12 * 2 = 24) and the other 12 are tripled (12 * 3 = 36). And because 24 + 36 = 60, you can use this new framerate for conversion into NTSC. Unfortunately, since not all frames are displayed for equal amounts of time using this so-called 3:2-Pulldown method, the film does not run quite as smoothly as in movie theatres.
This is how the Europeans solve the problem:
Europe's television standard is PAL which runs at 50 Hz. Unfortunately, you can't make 50 from 24 just doubling or tripling every other frame, at least not evenly. So the film is sped up 4% to 25 frames per second, those 25 frames are then doubled, and the end result is 50 Hz. And that's why almost all programs are too fast and too highly pitched by 4% in Europe. And it doesn't even matter if the program is english language, some european language or if it's a dubbing, everything originally made on film or NTSC is affected. Which is essentially everything except european television productions that are shot using PAL television cameras.
