vgtmpeg 1.3.22 is the initial release to bring Bluray support into vgtmpeg. BD support is still experimental and not as mature as DVD support. Be sure to try it out and let us knows of problems you may find.
In order to use BD folders you specify your input BD folder using the ‘bd url protocol’ like this:
> vgtmpeg -i bd://path_to_bd?title=5 outfile
You can learn more about how to use bluray urls and download vgtmpeg in the project homepage