4Media DVD Ripper for Mac,All-in-one DVD ripping software for Mac users. It can onvert DVD movies to most video and audio formats: DVD to AVI, MPEG, etc.
You can get 15% off coupon on their website.
You can try Handbrake. It has a disclaimer that it doesn't always work with the ancient AVI technology. AVI is around 11 or 12 years out of date. It is still in use by avid Windows XP geeks who, as you might guess, are not very concerned with being up to date.
From the Handbrake site:
"Outputs:
* File format: MP4(M4V) and MKV
* Video: MPEG-4(ffmpeg), H.264(x264), or Theora(libtheora)
* Audio: AAC, CoreAudio AAC (OS X Only), MP3, or Vorbis. AC-3 pass-through, DTS pass-through (MKV only)"
If you have the option, use "H.264" [[more properly called H.264/MPEG-4 Part 10 or H.264/MPEG-4 AVC (Advanced Video Coding)]] format. It is much more efficient and of higher pixel accuracy than AVI. Even Microsoft has finally added H.264 support in Windows Media Player 12 / Windows 7.
Handbrake does not remove copy protection. For that, use MactheRipper.