Ripping DVD's to Mpeg 4

Archived from groups: rec.video.desktop (More info?)

Here is what I am trying to achieve:

I have a number of commercial DVD's that I am trying to transfer to my Achor
media device.

By using DVD-Decrypter and ffmpeg I can convert most of them to mpeg 4
without any problems.

However, I have not been able to convert some of the disks, including
Monsters Inc and Back to the future Part 2 (1 works and havent tried 3 yet)

I am able to rip theVOB's to disk but when I start ffmpeg going the "bytes
processed" doesn't move and it appears not to do anything. There is a lot of
disk activity on the machine which implies it is reading the ripped VOB's

Any suggestions?

TIA

Dave