An Exiv2 user is adding ISOBMFF support to their private copy of the code. I invited them to provide their code as a “contrib”, however they didn’t reply to my invitation.
I learnt about this because the user emailed to ask about the availability of the code discussed in the book. The location is documented in the book, of course. I believe he intends to use the code in the book to read CR3 files.
contrib/isobmff could provide a script such as integrate.sh/integrate.cmd to make using the contrib very easy. I can’t say if that will satisfy everybody, however I suspect Jens would accept that as a good way forward.