is the exported avi jerky?

if not, it's a problem at the encoding stage.

I'm not really au fait with tmpgenc's in-depth options, but what level of motion compensation are you using? are you definitely encoding pal>pal or ntsc>ntsc, not pal>ntsc or ntsc>pal?

What frame rate are you making it if you're doing ntsc, 29fps or 24fps? Does that match the original video?

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