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Posted by Justin Cole on 12/12/06 20:06
"fwibbler" <thedoctor@thedeathzone.free-online.co.uk> wrote in message
news:gemini.ja4tug0018mdf0204.thedoctor@thedeathzone.free-online.co.uk...
> Hmmm, AIUI,
>
> Film is shot at 24 frames per second.
> NTSC works by slowing this to 23.976fps and taking every 4th frame and
> duplicating it. So for every 4 frames of footage, 5 frames get displayed.
> this brings the frame rate up to 29.97fps.
>
> This tends to lead to motion judder (not sure if that is the official term
> for it)
It's a little more complicated than that. Whole frames (2 interlaced fields
per frame) aren't duplicated, 3:2 pulldown is used where some fields are
shown for slightly longer than others. This does introduced a slight judder
on horizontal panning especially. Some people notice it others don't.
However, 3:2 pulldown removal on a non-interlaced display can almost fully
remove the problem. That way you don't get the frequent PAL audio-pitch
problem...
Justin.
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