On 6/8/05, Richard Prosser <rhprosser@gmail.com> wrote:
> As a quick query - if movies are 24fps & TV is 25fps (50Hz) - when I
> watch a movie on TV is is "properly" converted, or do I watch a
> slightly sped up version?

Yes.

> I guess running a 24 fps movie at 25fps would not cause too much of a
> problem

You're more likely to notice the audio being 4% sharp.

> but for 60Hz systems I don't think 30fps would be acceptable
> - apart from anything else, the sound would noticably increase in
> pitch

For 60Hz systems, a system called "2:3" pulldown is used.  (I think it
is less confusing to write it as "2,3" pulldown because it is a
sequence rather than a ratio).

NTSC video is made of 60 fields per second.  So if we repeat one frame
of 24 fps film for two fields, than the next frame for three fields,
we get 2 frames of film lasting for 5 fields of video.  2/5 is the
same as 24/60.

If you think this might add some artifacts, making motion less smooth,
you're right.  But those of us in NTSC countries are pretty well used
to it.

Regards,
Mark
markrages@gmail
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