You know the problem, a QuickTime is on your hard drive and it should lead to a DivX file. There are now more than 120 audio and video formats, because you very quickly lose the overview. Obviously there is something for everyone "right" program. But in the whole jungle codec is a priceless matter quickly.

What would these GNUWorld without a free open source solution? ffmpeg is the secret! With ffmpeg there is a library of all imaginable formats (codecs) supported. So right off, and then open the terminal and even a quick cryptic line, and it is already happening. My QuickTime DivX is .... oh? Terminal? Command line? Uh Hello? Ok back <<<<<<

For the Mac, there is a great GUI (Graphical User Interface) for: ffmpegX

How this tool works I show in my next workshop