Hi Isabelle,
[Isabelle Illya Guillemin] " Since most of my clips are VGA at 30 ip, I thought that reediting these files directly in FCP would be the best idea since they are the closest to Vimeo's pre requisite"
Vimeo can play videos with whatever time-base.
Changing time-base is always destructive, so if you can keep with the original 30fps, the best.
Use MPGStreamclip to convert your .mpgs and .avis to QT.
The best codec option is Prores. Keep the original size, and time-base. Uncheck the "fields rendering".
When you have your Prores master ready, you need to convert it to H264 for Vimeo.
rafael
http://www.nagavideo.com
