Rendow is a wonderful audio player.
You can change playback rate by walking(running).
* Accelerando: The app plays music faster as you run faster.
* Walking -> 1.0: When you are walking, it plays at normal speed.
* Running -> 1.0: When you are running, it plays at normal speed.
And you can create your speed-playbackrate graph.
• You can buy additional visualizations.
(Settings > Buy Visualizations > Store)