avisynth resizing

[lpn1160]

I have a winTV2000 pvr pci, when i capture to mpeg2 the res is 704x480,
when i capture to .avi i use a resolution of 352x480.
My goal is to make a vcd ntsc (352x240).
well my question is which method gives the best quality on down sizing to 352x240? reduceby2, bilinearresize,simpleresize?? I have tried them all and I really can't seem to distinguish a difference. Bicubic resize, I think is really just for upward resizing.
anyone know the real technicalities between all the different methods of resizing with avisynth???

Thanks

[therick]

use BilinearResize(352x240)-bilinear is best for sizing down.

[Poplar]

It depends on bitrates you're using. If you go for very high bitrate, such as over 2.5Mb/s, Bicubic is better.

[DJRumpy]

I've always been told bicubic is better, all the time. Which is it?

[fantomlord]

I've always been told bicubic is better, all the time. Which is it?

easy way to find out:
encode the same small clip using both for increasing and decreasing size, and compare them yourself. just make sure you change nothing else about the encode except the resizing methods so that you can compare just those.

[DJRumpy]

If you use the resize option in virtual dub, and use the preview option, you can see immediate changes to what your resizing. The 'Nearest Neighbor' looks bad (jaggies). The bilinear seems to blur the picture a little. The bicubic almost seems to do the reverse, and sharpen it a bit too much.

There are three different bicubic resize modes
=-0.75
=-0.60
=-1.00
Can you tell me the difference? I always just pick the last one. Using the preview, I can't tell a difference between these 3 modes.

[Truman]

As usual it depends on the source, bitrate, the other used filters etc. etc.
The widely accepted rule of thumb is, that bilinear should be used shrink the image and bicubic to up-scale the image.
Bilinear Resizes blurs the image, Bicubic sharpens the image more or less, it depends on the b/c parameters. Bicubic 0,1 will probably sharpen the most images too much. It may look nice in the preview, but if you convert at a low bitrate, the encoder has a dirty job. Very sharp edges require a high bitrate to encode it properly. Sometimes you will even end with ghost images.
For progressive sources (DVD to SVCD) usually I use Bicubic 0,0.5.
I agree with fantomlord, just do some tests.