Normaly thru a small software called DIVA. (is Freeware)
Than just to have all using the same Codec, i do open the File in Quicktime PRO and Export using the DV PRO Codec.

Works pretty well.

Gian

http://www.versiontracker.com/dyn/moreinfo/macosx/17899
http://diva.3ivx.com/