[MPlayer-users] Comparison of different software scaler types

[Corey Hickey]

Matthias Wieser wrote:
> Results:
> - sws 0    produces acceptable results
> - sws 1    produces blurred images
> - sws 2    produces very good images
> - sws 7    is even worse than -sws 1
> - sws 8    produces shadows near strong edges and increases contrast
> - sws 9/10 produce the fewest artifacts and gives even a bit better
>            results than -sws 2
> 

Hmm, interesting... That's neat to see the differences among them. I'm
by far not an expert on this, but, depending on your visual preference,
the more blurring scalers can be beneficial for encoding. For example:

mencoder lotr_test.vob -vf crop=712:354:4:62,scale=688:288 -sws 10 \
-nosound -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:mv0:trell:psnr:\
vpass=$i -o 10-"$i".avi -ofps 23.976

..results in this PSNR:
PSNR: Y:39.90, Cb:42.81, Cr:43.68, All:40.76

..whereas changing -sws 10 to -sws 1 gives this:
PSNR: Y:41.06, Cb:43.79, Cr:44.58, All:41.87

In the second case, lavc can more precisely encode the data getting
thrown at it. Here's a couple pictures:

http://bugfood.casa-z.org/sws/sws.tar.bz2  (332k)

or, if you're lazy :)
http://bugfood.casa-z.org/sws/159.1.png   (582k)
http://bugfood.casa-z.org/sws/159.10.png  (582k)

-Corey