Audio · 07
BPM and key
A tempo guess from the onsets, and a key guess from the pitch classes. Both are estimates. Treat them as a starting point for a session, not as a lab report.
How to use it
Tempo looks for a repeating energy jump between 70 and 180 BPM. A clear kick or clap lands close. A rubato intro, a half-time chorus, or a track with no drums can land on half or double time. Listen and decide.
Key builds a chroma from frequencies between 60 Hz and 2 kHz and compares it with the Krumhansl–Kessler major and minor profiles. A solo piano triad is easy. A song with a borrowed chord, a modulation, or a distorted bass is not. The label is the best single key over the whole file.
Nothing is downloaded. The analysis is plain DSP in the page. Give it at least a few seconds. A one-note hit has no tempo.
Tips
- If the BPM looks like half the tempo you counted, the beat is on the off-grid the algorithm preferred. Count a bar yourself before you lock a session tempo.
- Trim a representative section if the song changes key. The whole-file average will sit between the two.
- A vocal-heavy mix can pull the key toward the melody. That is often what you want for a cover, and wrong for the bass line.
FAQ
How accurate is the key?
On a clear major or minor chord it is usually right. On a dense mix it is a suggestion. Check it on a keyboard before you retune a vocal.
Why is there no Essentia or a neural model?
Essentia.js is AGPL, which does not fit a page people can use commercially without reading a network license. This estimate is original code in the site.
Is the song uploaded to detect the key?
No. The samples stay in the tab.
License
The tempo and key estimates are original code in this site. No third-party analysis library is bundled.