Expose VM

Many years ago, I created a modification to dvdbackup, called dvdbackupx, which uses the libdvdnav VM, to find the unused sectors, and skip them.

https://github.com/dmahurin/dvdbackup https://bugs.launchpad.net/dvdbackup/+bug/648708

As the VM interface is still not exposed, this required a modified libdvdnav which exposed the internal VM interfaces.

https://github.com/dmahurin/libdvdnav

Recently, there was some interest in dvdbackupx, https://github.com/dmahurin/dvdbackup/issues/1

But maintaining it is a challenge as it depends on libdvdnav internal interfaces.

Would the project be open to exposing the VM interface officially. Then such a unused-sectors change could also possibly be an official feature of dvdbackup, and perhaps "dvdread" (unrelated to libdvdread) as well.