Welcome to Breakfast Quay, home of high-quality C++ libraries for use by audio and music developers.
Currently available:
|  | Rubber Band Library High performance audio time-stretching and pitch-shifting. | 
|  | MiniBPM Simple music audio tempo estimation. | 
|  | bq* Libraries Modest libraries for audio tasks. | 
The libraries here are open source, and most require a commercial licence if they are to be used in a proprietary product.
|  | Commercial licences Buy a licence for commercial use of one of these libraries. | 
The company that made this, Particular Programs Ltd, occasionally publishes end-user applications too:
|  | Rubber Band Audio A convenient and flexible application for changing the speed and pitch of audio, powered by Rubber Band Library. |