How to use it
- Open your audio.
- In Effects → Speed and pitch, set the speed, for example 0.75× to practise or 1.25× for speech.
- Keep pitch on to stretch time without changing pitch, or off for a tape-style change.
- Use Semitones and Cents to change key without changing speed.
- Wait for the preview to render, compare with A/B, and export.
Two kinds of speed change
Tape-style (Keep pitch off) resamples the audio: everything plays faster or slower and higher or lower together, like a turntable at the wrong speed. This is exact and artefact-free.
Keep pitch on uses WSOLA, a time-stretch method that repeats or skips tiny overlapping slices of the waveform at points where they line up. It works well for speech and most music between 0.75× and 1.5×. At extreme settings, drums can smear and voices sound phasey. This feature is labelled APPROX for that reason; it is not a studio-grade phase vocoder.
Changing pitch only
Pitch shift resamples by the pitch ratio and then time-stretches back to the original length. One semitone is a ratio of 2^(1/12); cents are hundredths of a semitone for fine tuning against an instrument.
Questions
Does speed change affect my selection?
Speed applies to the whole timeline at render time, so the timeline length changes. Select and trim after the preview has rendered at the new speed.
What is the highest-quality option?
Tape-style (pitch follows speed) is exact. Pitch-preserving stretch is approximate; keep changes small for the cleanest result.
Can I change BPM to an exact tempo?
Divide the target BPM by the current BPM and type that as the speed, e.g. 120 → 126 BPM is 1.05×.