原文
Scales the image with the software scaler (slow) and performs a YUV<−>RGB colorspace conversion (also see -sws).
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.
-(n+8): Like -n above, but rounding the dimension to the closest multiple of 16.
0: off (default)
1: on
0: Use all available input lines for chroma.
1: Use only every 2. input line for chroma.
2: Use only every 4. input line for chroma.
3: Use only every 8. input line for chroma.
−sws 2 (bicubic): B (blurring) and C (ringing)
0.00:0.60 default
0.00:0.75 VirtualDub’s "precise bicubic"
0.00:0.50 Catmull-Rom spline
0.33:0.33 Mitchell-Netravali spline
1.00:0.00 cubic B-spline
−sws 7 (gaussian): sharpness (0 (soft) − 100 (sharp))
−sws 9 (lanczos): filter length (1−10)
qntsc: 352x240 (NTSC quarter screen)
qpal: 352x288 (PAL quarter screen)
ntsc: 720x480 (standard NTSC)
pal: 720x576 (standard PAL)
sntsc: 640x480 (square pixel NTSC)
spal: 768x576 (square pixel PAL)
0: Allow upscaling (default).
1: Disallow upscaling if one dimension exceeds its original value.
2: Disallow upscaling if both dimensions exceed their original values.
AviutilやAviSynthスクリプトで良く見かけるlanczos3は以下のようになると思われる。
-sws 9 -vf pullup,softskip,crop=w:h,scale=w:h:0:0:3,hqdn3d,harddup