Resizing Algorithms

[trg100]

Can anyone tell me if and how VDub's different bicubic methods (a=-1.0 etc.) correspond to the 'soft bicubic', 'sharp bicubic' etc. that I keep hearing about? Are these terms from AVISynth?

Which (VDub) method would you recommend for a movies at about 850kbps, 576x240?

[movmasty]

0.6 should be the "smoother" bicubic
1 the sharper one

and yes, this is a choice made after the avisynth notes on the sharpen quality of vdub bicubic

but in test that i made i got same video size for every different number......

[hakko504]

The terms soft, neutral and sharp bicubic comes from Gordian Knot. In AVISynth's bicubic resize there are two parameters for deciding how the bicubic works. The sharp bicubic is identical to VD's a=-0.75 but is denoted b=0,c=0.75 in AVISynth. The neutral was agreed upon as the best choise for most cases and has the parameters b=0,c=0.5. Note that this is a smoother filter than any that VD uses. And finally the smooth bicubic has the parameters b=0.333,c=0.3333 and should only be used if you try to cram in a long clip on very little space. Of course this is only valid in AVISynth. In VD there is almost never any reason for not using the a=-0.6 bicubic.