I have been using the following process to extract audio from DVDs. The process works OK, but I’m not sure whether any of the steps is compromising the quality of the final audio unnecessarily.
Step 1 - rip DVD to separate vob files per chapter using Smartripper
Step 2 - demux vob files to AC3 using DVDLAB (I already had DVDLAB and it can demux vobs - that is only reason for this choice of tool)
Step 3 - convert AC3 to WAV using Nero Wave Editor. (I just open the AC3 and “save as” WAV - no actual editing is done).
Step 4 - downsample from 48kHz to 44.1kHz and Normalise with Adobe Audition.
Could one of you good people advise if any of these steps is degrading audio more than would be the case with alternative methods. If you can recommend a way that gives noticeably better result, I’ll make the change.