copying video dvds

[smcg4191 at frii.com]

I generally mount and then use "cp" to copy my video dvds to
hard disk for convenience.  99% of the time this works fine
and the resulting directory is playable by vlc, etc.  
However occasionally I'll get an "Input/output error" when
copying a disc that vlc played fine and, unsurprisingly,
there are problems when later trying to play the copy.

I suspect that vlc makes use of error correction capabilities
on the dvd, whereas "cp" doesn't.

Is there some way or tool that will make a copy of the dvd 
using (or at last preserving in the copy so that vlc can use)
the error correction stuff on the dvd so that the copy is
playable even when there are some errors?