libsndfile
libsndfile is a mature open C library with consistent frame-based I/O for WAV, AIFF, FLAC, Ogg, and more.
Why use it
Audio importers, conversion tools, and analysis pipelines reduce format-specific code.
Where it fits
Find engines, frameworks, code libraries, version control, and production automation.
What to check
It does not cover every codec or real-time mixing; audit external codec terms and untrusted-file handling.