[MPlayer-users] Reverse PAL telecine

[Bryan Stillwell]

A couple years ago I bought a PAL DVD while on a trip to England.  Then
earlier this week I decided I would make a high quality backup copy of
the disc to my computer.  The problem is that I haven't been able to
figure out what the right options would be to undo the telecine on it.

To troubleshoot it I dumped 150 frames (6 seconds @ 25fps) to disk to
figure out what was going on:

    http://www.bokeoa.com/pal_telecine/

You'll notice that frames in multiples of 25 starting with frame 9 are
the cleanest (9, 34, 59, 84, 109, 134), but between those frames it goes
from slight interlacing to full interlacing and back.  I also noticed
that the interlacing seems to take 4 lines instead of the normal 2
(even/odd).  To make sure mplayer wasn't doing any scaling during the
dump that might have caused this, I used the '-aspect 720:576' option:

    VO: [png] 720x576 => 720x576 BGR 24-bit

I found that some of the deinterlacing filters seem to clear up the comb
effect some, but as I understand it, that cuts the quality in half
(which isn't what I want).  Ideally I would like to convert from the
25fps output back to the original 24fps in the cleanest and best quality
way possible...

Has anyone run into this form of telecine before and have any hints on
what I should do to reverse it completely?

Thanks,
Bryan