Best resize filter in Virtualdub

[cyclone5]

Is there a list anywhere of the pros and cons for the different resize filters in Virtualdub. Im trying to workout which one is best for a DVD to Divx rip, resized to 640 x 480, 700mb file size.

[mats.hogberg]

Lanzcos 3

/Mats

[cyclone5]

I had read elsewhere that Lanzcos wasn't good for file sizes of 700MB or less.

[mats.hogberg]

Que? What would the choice of filter have to do with the file size? Filters work on images.

/mats

[cyclone5]

I imagine it's because lower file size = lower bitrate. Lower bitrate means more artifacts which the filter is going to pick up.

That's what I thought it meant anyway, I think I read it on the Doom9 forums.

[junkmalle]

I usually use either Bilinear or Lanczos3. The others are usually somewhere in between these two. The output of Bilinear is a little fuzzy but compresses better. Lanczos3 is sharper but doesn't compress as well. Bilinear tends to decrease high frequency noise, Lanczos3 tends to accentuate it -- hence the differences in compressibility (noise doesn't compress well).

On a single frame basis Lanczos3 gives a better picture (sharper, less aliasing). But if you're goal is to shink a 90 minute movie down to 700 MB you'll probably be better off with Bilinear.

[celtic_druid]

A higher quality resize will make the output larger for the same quant. In other words if you are doing 2 passes, the 1st pass will be larger and the average quant of the 2nd pass will be higher.

So it is possible that you could get better quality be using a lower quality resize filter for a given filesize, however to say 700MB's or less don't use lanzcos, etc. is just wrong.

Personally I would suggest resizing via AVISynth so as to avoid a lossy RGB24 colourspace conversion.