[MPlayer-dev-eng] Custom soft-telecine patterns

[Ville Saari]

On Thu, Mar 17, 2005 at 05:56:18PM +0100, Nico Sabbi wrote:

> a) 3 0 1 2 2
> b) 2 2 2 2 2
....
> it seems that using pattern a) it's possible to telecine 25 fps 
> progressive video to 30 fps,
> and with pattern b) 25fps -> 29.97
> 
> It sounds convincing. Is it really? :)

A better pattern for 29.97 fps would be:

a) 3 0 1 2 2  repeated 83 times
b) 3 0 0 0 0  once
c) 1 2 3 0 0  repeated 82 or 83 times
d) 1 2 2 2 2  once

Instead of omitting two consecutive repeats once every 1001 frames,
this would omit just one every 1001 fields. The resulting artifact is
less visible.

But what would anyone need this for? This kind of processing won't
work for interlaced video and if you have progressive material at
25 fps, you most likely have sped up film, for which it is much
better to just interpret the framerate as 23.976 and then use the
usual field flag pattern.

A more general solution would be to accept an arbitrary input fps
between 20000/1001 and 30000/1001 inclusive and then just insert an
RFF and invert the polarity whenever you are more than half a field
behind the schedule. This would actually apply one-dimensional
Floyd-Steinberg dithering to frame durations.

-- 
 Ville