Library & files
Key detection
Key detection estimates a track’s musical key from the audio by measuring which pitches dominate and matching that profile against major and minor templates. It is an estimate, and it is confident even when wrong.
In practice
Trust key detection for sorting and check it by ear before you build a transition on it.
Analyse everything, then treat the result as a strong hint rather than a fact. The tell for a wrong reading is a blend that sounds fine on the drums and wrong the moment both basslines are present. If a track matters enough to plan around, listen to the two together at home once — that costs a minute and settles it. Where two detectors disagree, the answer is usually the relative major or minor of one of them rather than something unrelated.
Estimate
What the field holds
Relative
Where it goes wrong
By ear
What settles it
Where these come from: How chroma-based key detection behaves and where it fails — established signal-processing behaviour, not catalog figures. For what we can measure, see the pair that share every note.
Why it matters
It works best on exactly the music DJs play — sustained, tonal, harmonically simple records give a detector plenty to measure. It works worst on percussive tracks with almost no tonal content, on records that change key partway through, and on anything where the bassline and the pads disagree.
The failure that costs you is not a random wrong answer but a systematic one: relative major and minor share every note, so a detector that gets the pitch set right can still land a wheel position away. That is why a mix that should have been perfect sometimes fights you.
Frequently asked
Why do two programs give different keys?+
They use different templates and different weightings, and they disagree most often between a key and its relative major or minor, which share all seven notes. Your ears settle it faster than a third opinion.
Is key detection accurate enough to mix on?+
For narrowing choices, easily. For committing to a long harmonic blend on an unfamiliar record, check it once at home — a wrong reading sounds fine until both basslines arrive.
Can a track have more than one key?+
Yes, and plenty do. A detector returns a single answer for the whole file, so a record that modulates gets whichever section dominates the measurement.
Related terms
BPM detection
BPM detection finds the repeating pulse in a track by measuring where energy rises and looking for the interval that best explains those onsets. It returns a tempo and a grid, and both can be right about the wrong thing.
Musical key
The musical key is the note a track resolves to plus whether it is major or minor — A minor, F major. It is the same information a Camelot code carries, written the way a musician would write it.
Camelot key
Camelot notation renames every musical key as a number from 1 to 12 plus a letter — A for minor, B for major. 8A is A minor. Codes next to each other on the wheel share most of their notes.
Batch analysis
Batch analysis runs the tempo, key, grid and waveform detection across many tracks at once rather than as each one loads. It is processor-heavy, takes hours on a large library, and only has to happen once per track.
Explore: Song key and BPM finder · Do DJs actually mix in key · Camelot key · All DJ terms