What you get
A tonic and a mode — A minor, F major — and with it:
- the Camelot code, and the wheel drawn with the keys that mix with it lit;
- the tuning offset in cents, so you can see how far off A = 440 the material actually sits;
- a confidence band, with the second-place key named when the call was close.
Detuned material still resolves
This is the difference that shows up in real work, and almost nothing else in this category handles it.
Key detection works by measuring how much energy sits at each of the twelve pitch classes. If the material is sitting slightly off A = 440, that energy smears across two neighbouring pitch classes — and a tool that assumes standard tuning will confidently hand you the wrong key.
Off-tune material is not an edge case:
- Sample packs are routinely recorded, resampled or bounced slightly off pitch.
- Anything pitch-shifted is off the grid by definition. Pitch a loop up two and a half semitones and it is no longer at concert pitch.
- Vinyl rips drift. Tape drifts. Old hardware drifts.
DropWave measures the tuning rather than assuming it, corrects for it, and then tells you what it found. A reading of "A minor, measured at −38 ¢" gives you the key and the fact that the file is a third of a semitone flat — which is usually the more useful of the two, because it tells you what to do next.
The tuning offset, in practice
| What you see | What it means |
|---|---|
| Within a few cents of 0 | The material is at concert pitch. Nothing to do. |
| 10–50 cents either way | It has been shifted, resampled or recorded off-pitch. Correct it, or pull the rest of the session to it. |
| Close to ±50 cents | It is sitting almost exactly between two semitones — worth listening before you commit. |
When a file has no key
Worth saying plainly, because no tool in this category says it:
- Drum loops and percussion have no key. You will still get a reading — noise correlates with something — and a low confidence band is the correct description of that situation.
- A minor and C major contain the same notes. Only which one the music resolves to separates them, and eight bars of a loop may not resolve anywhere. If the named alternative is the relative key, both answers are defensible and your ear decides.
- Tracks that modulate have more than one key. You get the one that dominates.
- One-chord pads and filtered noise have no tonic to find.
In each of those cases the useful output is a low band and a named alternative — which is what you get, rather than a number that looks certain.
What it is not
There is no model and no inference here. The same file always produces the same answer, and nothing is sent anywhere to produce it.
Related
BPM · Camelot wheel · Key finder · How to find the key of a sample