[MPlayer-DOCS] scale video filter

[Diego Biurrun]

D Richard Felker III writes:
> On Sat, Sep 11, 2004 at 09:33:22PM +0200, Diego Biurrun wrote:
> > 
> > In the description of the scale filter d_width and d_height is
> > mentioned:
> > 
> > scale[=w:h[:interlaced[:chr_drop[:param[:presize]]]]]
> >   Scales the image with the software scaler (slow) and performs  a
> >   YUV<->RGB colorspace conversion (also see -sws).
> > 
> >   w,h
> >     scaled width/height (default: original width/height)
> >     NOTE:  If -zoom is used, and underlying filters (includ-
> >     ing libvo) are incapable  of  scaling,  it  defaults  to
> >     d_width/d_height!
> >       0:   scaled d_width/d_height
> >      -1:   original width/height
> >      -2:   Calculate w/h using the other dimension and the
> >            prescaled aspect ratio.
> >      -3:   Calculate w/h using the other dimension and the
> >            original aspect ratio.
> > 
> > What the heck is d_[height|width]?  Attila said it was an internal
> > libvo variable.  He did not know whether this was before or after
> > aspect correction, though.  Can somebody shed some light on this?
> 
> d_width/d_height is the final "intended display size" passed out from
> all previous filters. naturally this incorporates aspect.

I'm not sure everything is clear yet.  Is something like the following
description correct?

w,h
  scaled width or height (default: original width or height)
  NOTE:  If -zoom is used, and underlying filters (includ-
  ing libvo) are incapable  of  scaling,  it  defaults  to the
  width or height after filtering and scaling.
    0:   aspect after filtering and scaling
   -1:   original width or height
   -2:   Calculate width or height using the other dimension and the
         scaled aspect ratio.
   -3:   Calculate width or height using the other dimension and the
         original aspect ratio.

I've also removed the / since they might indicate division in the
context of aspect.  This was confusing me.

Diego