MKVtools with Leopard. But in the official web site:Are there any OS X solutions for this?
Byeand should also run on Mac OS X 10.4.x though there has only been limited testing. WARNING: Mencoder appears to have an issue with Power PC computers when trying to set the aac audio to low complexity, so mp4 encoding might not work for those users. Other functionality seems to be OK.
i think mkv2vob is the best program for converting high quality movies.