[MPlayer-users] Quick question: Aspect or Resize?

[Michael Niedermayer]

Hi

On Tuesday 16 April 2002 02:05, Felix Buenemann wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>
> On Tuesday 16 April 2002 00:42, Michael Niedermayer wrote:
> > [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> > Hi
> >
> > On Tuesday 16 April 2002 00:00, Felix Buenemann wrote:
> > [...]
> >
> > > If you are downscaling it's ok to use a bilinear scaler, like -sws 0,
> > > if you are upscaling and want top qulity you should choose bicubic
> > > scaler (-sws 2). Some people believe bicubic scaler helps for
> > > downscaling too, however I don't believe so. (bicubic is slower then
> > > bilinear)
> >
> > i wouldnt use -sws 0 for downscaling, i would recomand -sws 1 (bilinear)
> > or 2 (bicubic)
>
> what's the difference between -sws 0 (fast bilinear) and 1 (bilinear)?
-sws 0 does billinear interpolation
-sws 1 does billinear interpolation (more accurate too) for upscaling & 
bilinear decimation for downscaling
-sws 2 like 1 just with cubes ;)
-sws 0 has the same downscaling problem as most hw scaler have, it uses only 
a few samples for each output sample, it simply ignores the pixels inbetween

> Btw. do you really think it makes visible difference for downscaling? Or
> you use some special hacks to speed up fat bilinear?
just try 
./mplayer -vo x11 -sws 0 -x 32 -y 32 ~/videos/xXx_DivX.avi -zoom -osdlevel 0
./mplayer -vo x11 -sws 1 -x 32 -y 32 ~/videos/xXx_DivX.avi -zoom -osdlevel 0
./mplayer -vo x11 -sws 2 -x 32 -y 32 ~/videos/xXx_DivX.avi -zoom -osdlevel 0
to see the difference between them, u will see that -sws 1 looks a bit 
blurry, -sws 2 looks sharper, and -sws 0 looks bad

[...]

Michael