[MPlayer-users] Re: Crop before deinterlacing OK?

[Matthias Wieser]

Am Sonntag, 24. Juli 2005 22:30 schrieb RC:
> Years ago I tried pp=lb vs. pp=md and was surprised how much better lb
> compressed.

lb works comparable to a vertical gaussion blur filter. This results in 
less noise and softer edges. Both are beneficial for compressibility.

On the other hand pp=md results in much sharper edges (at least as sharp 
as the original) and vertical micro-blocks (1x2 pixel).
That's very bad for compressibility.

> Just now I tried pp=lb vs. kerndeint and found pp=lb to produce 45%
> smaller files (using vqscale=2) in a high-ghosting clip.

During high motion scenes kerndeint has pp=ci characteristics. So it 
throws away halve of the lines and does an interpolation. So there are 
interpolation artifacts and there is no noise-smoothing by blendung two 
fields into each other. Additinally the local contrast is not lowered 
(think of a black, 1 pixel high horizontal line on white ground which 
becomes gray and blurry after applying pp=lb)

=> no question, the output of kerndeint during high motion scenes is more 
noisy, has higher contrasts and some interpolation artifacts which all 
hurts compressibility. But on the other hand you have the advantage of 
nearly unaltered frames during no motion scenes.

Maybe kerndeint could be improved by replacing the cubic interpolation by 
the pp=fd interpolation which gives nicer edges.

Maybe someone ports some additional deinterlacers from dscaler...

> (Cue the 
> "lb halves the resolution" comments).
                ^
             vertical

Regards,
  Matthias