Colour artifacts after resizing

[OcellNegre]

Hi guys!

I've found nothing to help me in the forum so I start this new thread.
I've downloaded a little movie, but the size was completely incorrect (so deformed). Then, I tried to resize it in Virtualdub but when I reencode it the colours are bad. Well, it appears with large one-colour areas where it shoud be different similar colors or gradients. If I don't resize there are no colour artifacts. I have to resize from 640x360 to 508x360.
Any idea?
should I post it into virtualdub forum?

Thanks a lot.

[Acaila]

Divx is quite picky about resizing. DXN (I think) says that width must be divisible by 4 and height by 2, however that doesn't always work as you've just found out.

The only real safe way is to have both height and width divisible by 16. In your case that would result in either of the following:
1) 496x372 (4:3 AR)
2) 496x279 (16:9 AR)
3) 512x384 (4:3 AR)
4) 512x288 (16:9 AR)
Not counting cropping.

I've never been a star at Aspect Ratio's, so those examples could be off...

[OcellNegre]

Thanks Acaila!

I've tried several resolutions, and I've found out that, after resizing and reencoding, the safest resolutions are those that are divisible by 16 in both width and height. But I've also noticed that encoding a dvd or an uncompressed avi it's not necessary, almost for the video data I have.

The resolution I've chosen is 496x372 (4:3 AR), and it worked.:)