Is there a way to find out which codec Avisynth is using to decode MPEG-4 videos? As you know there are so many codecs around and some codecs play more than 1 type of codec which may not be good. Divx 5.1, I think can decode Xvid videos, not sure about vice versa. Is there a way to know which codec Avisynth is using to decode my Xvid/Divx3,4,5 videos? Is GSPOT accurate enough? I noticed that my Xvid videos suffers in smoothness when being decoded by Divx 5.1. Is there a way to tell Avisynth/WINDOWS to use the right decoder for the correpsonding codec?

Avisynth always use the codec that has the highest merit for a given format. And this is th eone given by Gpot !

The merit is a way to classify the codec within the system. It's a little complicate to explain but, yes, you can tell to windows with codec to use by modifiying it's merit.

I suggest you to use zoomplayer for that. But be carefull : it is VERY tricky !

Oooo scary....... I think I'll just use the simple method of uninstalling and reinstalling again when needed. Unless there is a website that describe this tricky process.