2.2 is out the door, now with a better metadata handling system and improved file detection routines. The get_metadata() and set_metadata() routines were simply getting too complex so they've now been simplified and the burden of metadata conversion has been shifted to the metadata formats themselves.
In addition, track detection is much improved. Instead of taking a small chunk from the file header, the is_type() routines now get a seekable file handle to work with and can bounce all over the file if need be.
I'm anticipating the 2.3 release will focus on adding new audio types, but I wanted to get this maintenance release out before starting on something new.