Original

scale=312:252 -sws 0

scale=312:252 -sws 1

scale=312:252 -sws 2

scale=312:252 -sws 3

scale=312:252 -sws 4

scale=312:252 -sws 5

scale=312:252 -sws 6

scale=312:252 -sws 7

scale=312:252 -sws 8

scale=312:252 -sws 9

scale=312:252 -sws 10

    Software scaler
Command:
/big/download/mplayer/MPlayer-CVS/MPlayer/mplayer /big/Medien/Video/videotest/raw_detailliert.avi -ss 00:00:07 -vf crop=624:504:48:36,scale=560:454,scale=500:416,scale=440:344,scale=312:252 -sws 10 -frames 02 -vo png:z=0 -nosound