BiCubicResize

[24hourloop]

Why does DVD2SVCD by default use BiCubic Resizing? I know I can override it manually but even Avisynth's author told me once that it didn't buy you anything. He acutally mentioned that it gave the appearance that is sharpened the picture, causing the compression to work not quite as well.

At any rate; The best program for conversion so far.

[mrbass]

not sure...but if anyone has time on their hands you could test which one gives better results.
Also if one wanted better quality one would use the IDCT 1180 or whatever instead of 32-bit SSE but I've been too lazy to try since DVD2AVI manual says "perceptually" there's no difference. Which I take it as the human eye wouldn't notice.

[daxab]

I prefer BilinearResize because I find that with bicubic I see sharpening artifacts around high-contrast picture elements, like the edge of a dark building against the sky -- I see what looks like a shadow.

I edit the .avs file after DVD2AVI and change the bicubic resize to a bilinear.

[waldok]

Daxab,

DO you know that you just said something of the highest importance to me ? Man, I've been fighting with this "shadow" stuff along edges for months, but, sumb as I am, I never even thought about using Bilinear instead of Bicubic.

Man, I vote you for next US President (beware of Bretzels though).

Can't wait to try this tonight (not the Bretzels, the Bilinear stuff).

Waldok:cool:
(Time for my pills I guess)

[daxab]

waldok:

Let us know how it works out. BTW the new 1.0.6 release support bilinear resizing without editing the .avs file! Yes!

[Jono182]

so what are the pros and cons of linear vs cubic? can anyone give a quick rundown...thx

-jon

[daxab]

From the Avisynth docs (http://www.math.berkeley.edu/~benrg/avisynth-reference.html):

If you are magnifying your video, you will get much better-looking results with BicubicResize than with BilinearResize. However, if you are shrinking it, you are probably just as well off, or even better off, with BilinearResize. Although VirtualDub's bicubic filter does produce better-looking images than its bilinear filter, this is mainly because the bicubic filter sharpens the image, not because it samples it better. Sharp images are nice to look at--until you try to compress them, at which point they turn nasty on you very quickly. The BicubicResize default doesn't sharpen nearly as much as VirtualDub's bicubic, but it still sharpens more than the bilinear. If you plan to encode your video at a low bitrate, I wouldn't be at all surprised if BilinearResize yields better quality.

[Radioman]

This is another nice explenation on the same subject.

http://168.144.91.167/nickyguides/bilinear-vs-bicubic.htm

:cool:

[Linux]

I also prefer bilinear that often takes less time to compute.

I have made some nonstandard SVCD with 360x576(Pal).
In this case there is no reason to use Nearest Neighbor instead since 360 is half 720. And Nearest Neighbor gives in this case very good picture and very fast conversion. What it does here is dropping every other pixel.
In this case there is no quality gain in using either bilinear or biqubic.

Many program refuse to make SVCD at 360x576, they say that the width must be multiple of 16. That leads to 352 or 368. And at 352x576 it is impossible to get good quality with Nearest Neighbor.

DVD2SVCD is converting from a media with 720(DVD) to another with 480(SVCD) which is a downsize with 1.5. This simple transformation, from 3 to 2 would be best with bilinear.

The better look from bicubic some have seen is the same as using an artificial sharpening filter.
A DVD movie has such high picture quality from the start that it does not need this kind of filter.

[Jono182]

thx for the info...perhaps bilinear should be default for dvd2svcd or at least a selectable option w/o having to edit the .avs script?

-jon

[dvd2svcd]

Well, some likes Bicubic some likes Bilinear. Personal I like the former, so that's what's default. If I change that I'm sure a lot of other users would be unsatisfied. So I'll leave Bicubic as the default resize method for the time being.