Convert DVD to MKV (et al) without transcoding/recompression

I tried mkvtoolnix and it did it instantly, maybe because of copy-on-write feature of Btrfs I use.

There are probably many options, but I use k9copy for this. I use the wizard and select the option "Rip DVD without encoding". It produces a single MPEG-2 file of the selected tracks.

MakeMKV seems to be working for me.

http://www.makemkv.com/forum2/viewtopic.php?f=3&t=224

Just extracts the non-trivial sized titles from a DVD, puts them un-transcoded in an MKV file. Includes default audio track and the subtitles tracks.

Also does blu-ray apparently (I don't have a drive)

Handbrake doesn't do what you're asking for but it's the best I've found so far for making painless, compressed copied of titles on commercial DVDs

http://handytutorial.com/install-handbrake-in-ubuntu-12-10-quantal/

That guides for 12.10, but it works just fine for 12.04 as well. The bit that had me stumped was the package is called handbrake-gtk, not handbrake.

My first attempt with handbrake has compressed 40 minute extras video from a DVD from 1.3GB to 0.3 GB at > 100fps on my PC of, at this point, fairly obsolete power.

However the loss in quality was noticeable to my overly critical eye, but you can bump the quality easily by decreasing the quality slider by small amounts.