Maximilian is a C++ library, designed to ease the use of a wide array of audio features, ranging from synthesis and effects to multichannel audio, FFT, music information retrieval and granular synthesis. It has a syntax and program structure based on the popular ‘Processing’ environment. It’s designed to be cross platform and accessible. It’s lightweight, highly functional and sounds great.
Check out the repository and OpenFrameworks examples:
http://maximilian.strangeloop.co.uk