Playing DVDs from a USB DVD drive

[irob2345]

Is it possible to do this, in the way that VLC for example can?
We use a number of V7tt boxes for H264 playout from USB drives to an analog TV network for vintage (50's, 60's) TVs. They work very well in this role, where we need 4:3 aspect ratio.
The still picture mode is great for test patterns.
Next we will move the content to a common network drive and play from that.
Being able to play ad-hoc (unmodified) DVDs would be a useful addition.