Originally Posted by sefmiller
So on a PC, a film is not played at the source FPS?
Unless some speed-up or slow-down is being done, then it will be replayed at the source fps, though it may not be displayed at this rate.
If you play a 25fps movie on a 60fps display, you don't speed up the 25fps to 60fps, instead you repeat frames (or in some cases interpolate new ones).
Is this why sports are said to have a higher framerate. because the director, producer or editor chooses to increase the frame rate?
Hmm - lots of confusion here.
In broadcast there are two major territories :
50Hz (Europe - inc UK, much of Asia inc India and China, Australia/NZ, some of South America)
60Hz (North America, Japan, Korea, some other bits of Asia and some of South America)
In 50Hz territories broadcast video is either shot at 25Hz or 50Hz. 25Hz is usually shot 25p, 50Hz is shot either 50i or 50p (50i is sometimes called - confusingly - i25) Most broadcasters broadcast 25p as 50i - it still looks 25p and has 25p motion. Usually 25p is used for drama, high-end documentary, and quite a lot of factual. Usually 50i/50p is used for entertainment, sport, some soaps, news etc. 50i/50p native has twice the image rate of 25p - so motion looks much more fluid. 25p is displayed at 50p simply by showing every frame twice. 50i is displayed at 50p by de-interlacing.
In 60Hz territories broadcast video is usually shot at 24Hz or 60Hz (with some 30Hz). 24Hz is shot 24p, 60Hz is shot 60i or 60p. 24p is displayed at 60i/p by repeating one source frame 3 times, the next source frame twice, giving motion judder to linear movement (some people see this more than others) 30p would be displayed at 60p by repeating every frame twice. 60i is shown at 60p by de-interlacing.
Producers/directors will chose whether to shoot 'film look' (24p in 60Hz or 25p in 50Hz) or 'video look' (50i/p in 50Hz or 60i/p in 60Hz)
Also, if a 1080p/is 25hz only, is there the potential that a source could be faster on SD then HD?
1080i can be considered 50Hz - as each frame is made from two fields, which can be captured 1/50th second apart, delivering 50 different images per second, compared to the 25 images per second of 25p.