Rubber Band Library
An audio time-stretching and pitch-shifting library for use by applications developers.
Rubber Band Library is a high quality software library for audio time-stretching and pitch-shifting.
Rubber Band Library is intended for use by developers creating their own application programs rather than directly by end users, although it does also include a simple (free) command-line utility program that you can use for fixed adjustments to the speed and pitch of existing audio files.