Download
Smart Ripper and
HeadAC3he.
In SmartRipper:
(If it comes up at the start telling you some chapters are locked, open it in your usual DVD playing program and go to the main menu, then try again.)
Under "Input", find the right Program Chain. The length is in brackets, so if you want to record the main film pick the one that's a couple of hours. The others are likely to be special features.
Under "Stream Processing", make sure "Enable Stream Processing" is checked. Select the Stream which says "AC3" somewhere in the description (if there are more than one, try the first). Which this checked and selected, click "Demux to extra file" on the right. It should look like
this
Where it says "Target" at the bottom, browse to where you want the file to be saved to. You can change the filename too.
Hit Start. This will take quite a while and you should end up with a .AC3 file.
In HeadAC3he
Click "Log <<" and "Options >>" to close the log and open the Options menu.
Click "Source File" and browse to the AC3 file.
Set the options as I have
here
Hit Start.
This'll give you a big WAV file.