This demo shows time stretching independent of pitch. See here for more info. The stretch factor in the form below describes how to change playback speed. For example, 2 will play the song back twice as fast and 0.5 will play the song half as fast. Slowing down the audio is generally more computationally intensive than speeding it up.
Note: In this demo, the stretching is done before playback (for simplicity). Most inputs should take less than a second to process, but some may take more than that (depending on the stretch factor, the algorithm used, and the audio itself). You can open up the developer console to see stretching progress.
Kali can also be used for realtime processing. Demo coming soon.