Downloaded your sample a few hours ago. I must recall from my memory, cos I deleted it after viewing. Did you try to crop the original a little bit more into the video? As far as I could see there are strange short black borders at the top of the movie changing from scene to scene. Just try to cut a little more into the movie and make sure your resolution is dividable through either 32 or 16.(On GKnot's resolution tab). Maybe its a good idea to post your avisynth script for further investigation. To me it looks like it's the source which causes the malfunction of the encoders. Cheers Taurus