libsndfile Development
libsndfile is being developed by a small community of users and hackers. People interested in helping can raise an issue on Github.
The main repository can be found on Github:
https://github.com/libsndfile/libsndfile/
and includes instructions on how to build libsndfile from the Git repo.
If you are interested in how to add a new format to a libsndfile, you may find this FAQ helpful.