Again on how to transcode vobs already on my hard disk

It happens I got a DVD to rip, but I had no time to wait transcoding 
completed. So, I thought it was a good idea to extract the only chapter 
in it and gave back the disk. Now, I'm trying to transcode the vobs 
dvd::rip copied, but, as far as I can understand, dvd::rip itself cannot 
use them without other files it finds on the disk or an image of it.
Is that correct? And, if in case, is there a workaround to let me be 
able to transcode these vobs?

Thanks,
G.