How to unpack DVD movie to edit it's video/sound?

[Strong]

I wrote recently, but did get any respond, trying to rewrite another
way...
I have a DVD movie, that needs to be edited: video and sound.
Thus the question is: what software i should use to unpack from its
format to the format that will be operable for the video audio
processing as the next step?
Finally, i want to compile it in DVD format again. So, it will be nice
to loose its quality minimally. Big thanks, for Your solutions!
-- 
Best regards,
Strong.