GoAudio is an audio processing library, currently supporting WAVE files, although some tools such as the synth and breakpoints are encoding-agnostic, so you could combine them with a different library for storing the data and using GoAudio only as a means to generate the waveforms.

Features

• Wave file handling(READ / WRITE Wave files)
• Synthesizer - Create different waveforms using different types of oscillators
• Breakpoints (create automation tracks / envelopes)

Blog

If you want to know more about how this code works and what you can do with it, I write about this code and other audio related programs over on my blog: dylanmeeus.github.io.