High Quality FLV from any media file?

I've spent some time searching for that one treasure program that can create high quality FLV from almost any media file. I've come across two programs one of which I currently have installed which is Riva FLV Player and Video Charge Studio. Now I'm a bit skeptical if either program could produce high quality FLV which is why I've decided to ask here if anyone has any recommendations, or hopefully the treasure program that I may be looking for, that will do it and do it well !