Talk:Video Playback Slightly Too Fast
Contents
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And it doesn't even matter if the program is english language, some european language or if it's a dubbing, everything originally made on film or NTSC is affected.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.
source: http://sandbox.slysoft.com/palspeedup/index.html
Did you know that PAL is 4% faster than NTSC?
Just wanted to mention this. From the perspective of a perfectionist, I prefer to watch videos in the standard it was originally produced in. In order to make framerate conversion from NTSC (29.97 fps) to PAL (25 fps) relatively elegant, the PAL result is sped up 4%, which also affects the pitch of the sound. This means for example that when you watch a US TV series in Europe, you have to be aware that the real voices of the actors are actually a bit lower in pitch, and theme music slower. So this is really a kind of reality-distortion, but it has been accepted for decades. I'm not sure, it might be that with advances in technology it is possible to do the conversion more elegantly and without speedup now. I think I've seen examples where PAL was identical to NTSC. But I'm not sure whether the PAL version is also perfectly fluid. Because that's another thing you should know: NTSC converted to PAL is not fluid. You will recognize irregular motion especially in scenes with fast camera pans.
Being aware of this, you now might develop an increased annoyance over people who don't mention the relevant information in a torrent description. Wink
By the way, while audio editings like pitch shift or speedup while preserving pitch will be audible, merely changing the speed without keeping the pitch fixed seems to sound perfectly original. I once had a video in NTSC and in PAL in another language and wanted both languages in one file, but the PAL video was 4% shorter. So I reduced the speed of the PAL audio track and added it to the NTSC video. (You should then check whether the pitch is the same in both tracks. If not, you've probably encountered a more sophisticated PAL conversion.) (This post was last modified: 22nd October 2010 00:02 by Owledge.)
