On Sun, Mar 20, 2005 at 02:23:32PM -0500, Cory Papenfuss wrote:
> On Sun, 20 Mar 2005, Sergey Alexandrov wrote:
> > What I did: record 5-minutes mpg with fast scene changing,
> > went through it frame-by frame and saw that every three frames
> > form 5-frame sequence non-interlaced, i.e. frame sequence looks like:
> > 2 interlaced frames - 3 non-interlaced, 2 interlaced ... and so on.
> > It can be seen clearly on tv. I've checked it with Myth xbox frontend,
> > gmplayer, xine and totem, so looks like the problem is in mpg file.
> > I have about 15 movies on disk and I found all of them have the same
> > 5-frame sequence. Because of that, video looks a little bit jittery.
> >
> > Could anybody confirm that?
> >
>       Was it a telecine'd source?

Indeed, Sergey, it sounds like the program you were recording
originated on film, at 24 frames per second.

Since NTSC is a 60 field per second format, the common solution is to
use a procedure known as 3:2 pull down, the result of which is what you
see: 3 frames where the two fields came from the same frame of film,
and 2 frames where the two fields came from different frames.

Though, on looking around a little, I think you have the counts
backwards.  Look at the second and third pictures on this page:  

http://www.digiconform.com/24vs30.html

and you'll see that it *should* be 2 stable frames, and 3 mixed ones,
repeating.  If you really are seeing *3* stable frames in a row, then
someone, somewhere, has probably done something wrong, and that's why
it looks weird.

Cheers,
-- jra
-- 
Jay R. Ashworth                                                [EMAIL PROTECTED]
Designer                          Baylink                             RFC 2100
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      If you can read this... thank a system adminstrator.  Or two.  --me


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