AudioStretch

What it does

A standalone pitch and tempo editor. It opens an audio file, draws the waveform, and puts pitch in semitones and speed in BPM on separate controls along the bottom, each movable while the file plays. Saving writes a new file with the shift recorded in its name, so a semitone down or a tempo change shows in the file browser afterwards. There is no AUv3, so material leaves the DAW, gets corrected here and comes back in.

In the demo

Jade sings over a GarageBand piano part, transposes the piano down a semitone, exports the vocal as an uncompressed WAV through AudioShare, and brings the corrected take back in key. She then does it the hard way, singing a semitone low at 84 BPM against a song written at 78, and reverses both the pitch and the tempo in the app to land back in time.

Worth knowing

The speed control steps in fives, so she overshoots the figure she wants more than once before settling on it. Vocals are the hardest case and she picks them deliberately. A free lite version exists with some features locked, for trying the round trip before buying.