[MPlayer-dev-eng] Framerate filter?

[D Richard Felker III]

A few people have raised the issue of using the "detc" filter with
mixed hard/soft telecined DVDs, and up til now my response has just
been to say that it won't work. However, this isn't very comforting...

The problem is that to drop 30 fps down to 24, the filter has to drop
frames, one out of every five. But if some of the content is 24 fps
(soft telecined) progressive, and some is 30 fps hard telecined, the
filter can't tell which is which, and so it will also drop frames
during the soft telecined sequences, making video very jerky and
horrid.

IMO, the solution is to move the frame skipping (and possibly also
duplication) code OUT of mencoder.c, and into a video filter. This
filter would normally be loaded first when running mencoder (for
legacy behavior), but it could instead be loaded after telecine
removal. What it would do is read an exported PTS value from
mplayer/mencoder, and use this value to decide whether or not to drop
a frame.

However, I'm still not really familiar with how mencoder's a/v sync
works, and I wouldn't want to make such a big change without thorough
discussion of the matter with people who understand it better. Is my
idea the appropriate way to handle the problem, or is there a better
way?

Rich