Looking For a Music Transposing App

[Newbert]

Does anyone know of an app that can transpose the key (and perhaps playback speed) of an audio file such as an mp3? I'm thinking of something similar in functionality to several PC software titles such as "Transcribe!" or "Amazing Slow Downer".

Does such an app exist?

Thanks.

 

[MC6800]

Garageband seems to be able to do it. You add an "Audio input" track, add your mp3 to it using the "loop" tool, then edit that track and change its key using the "gear" tool.