name='GoggleboxUK']Oh Christ, I'm going to have to get technical in order to explain that a second only ever lasts a second no matter how many frames there are in it.....
There is a large difference in framerate between film, which runs at 24.0 frames per second, and the NTSC standard, which runs at approximately 29.97 frames per second.
Unlike the 576i video formats this difference cannot be overcome by a simple speed-up.
A complex process called "3:2 pulldown" is used. One film frame is transmitted for three video fields (1½ video frame times), and the next frame is transmitted for two video fields (one video frame time). Two 24 frame/s film frames are therefore transmitted in five 60 Hz video fields, for an average of 2½ video fields per film frame. The average frame rate is thus 60 / 2.5 = 24 frame/s, so the average film speed is exactly what it should be. There are drawbacks, however. Still-framing on playback can display a video frame with fields from two different film frames, so any motion between the frames will appear as a rapid back-and-forth flicker. There can also be noticeable jitter/"stutter" during slow camera pans (telecine judder).
To avoid 3:2 pulldown, film shot specifically for NTSC television is often taken at 30 frame/s.
For viewing native 576i material (such as European television series and some European movies) on NTSC equipment, a standards conversion has to take place. There are basically two ways to accomplish this.
* The framerate can be slowed from 25 to 23.976 frames per second (a slowdown of about 4%) to subsequently apply 3:2 pulldown.
* Interpolation of the contents of adjacent frames in order to produce new intermediate frames; unless highly sophisticated motion-sensing computer algorithms are applied, this introduces artifacts, and even the most modestly trained of eyes can quickly spot video that has been converted between formats.