Just look at this professional dvd to avi mac Tool
DVD to AVI Mac Software is specially designed for mac users to rip dvd movies to avi format for playback on your iPod, iPhone, mobile phones or other popular devices.
Following provides free download way, it does not contain any malware, so you can free download it with safty!
So how to fastly rip dvd movies to avi format without any problems
:After download this free trial, run it, then you shall see this familar screenshot in front of you like below:
:Import dvd files by click"Load DVD" button from your local computer
:Select output avi files and remember select a directory to store converted files
:You can press"Settings" button to customize output files, if you want to merge these dvd movies together, you can check before"Merge into one file"
:Press 
button to expand edit funtion window, you can press their own button to get your ideal effect
:Press"Start" button to let it start rip dvd movies to avi video automatically! Enjoy movie on your trip easily.....