Moving pitch without moving the clock
Pitch and speed are physically linked. Play a record faster and it rises in pitch; that is one change, not two. Separating them takes real work, and this tool does it in three stages: it resamples the audio to shift the pitch, restores the original sample rate, then time-stretches to put the duration back where it started. The result is a file the same length as the original, in a different key.
The range is twelve semitones either way — a full octave up or down. Semitones are the right unit here because they are musical rather than arithmetic: twelve semitones up is exactly double the frequency, and each step is the distance between two adjacent keys on a piano.
How far you can push it
- 1 to 2 semitones — essentially transparent. This is the range for nudging a track into a singer's comfortable key.
- 3 to 5 semitones — clearly audible as a key change but still natural. Fine for instrumental backing.
- 6 to 8 semitones — voices start to sound processed. Usable for effect, less so when you want it to pass unnoticed.
- 9 to 12 semitones — an obvious transformation. Good for character voices and sound design, not for material meant to sound unedited.
Shifting down tends to sound better than shifting up by the same amount. Raising pitch compresses the harmonics into a narrower space and exposes the stretching artefacts more readily.
Common reasons to change key
The most frequent is vocal range: a song sits two semitones too high for the person singing it, so the backing track comes down two semitones and everything else stays as it was. Pair this with the Karaoke Maker and you have an instrumental in a workable key.
The second is matching. Two tracks you want to blend are in different keys, and moving one by a couple of semitones lets them sit together. The third is repair: a recording made on equipment running slightly off speed can be corrected, though if the whole recording is off you usually want the Speed Changer as well.
If you want pitch and speed to move together — the tape effect — use both tools in the same direction rather than expecting this one to do it. They are deliberately independent. Preview is local; the shift is rendered on the server at export and the file is deleted immediately after.