Question 1

How accurate is the key detection?

Accepted Answer

On clear tonal music it is usually right, and when it is wrong it is normally off by the relative major or minor — which is why the runner-up is shown next to it. Modal, atonal and heavily processed tracks are the hard cases.

Question 2

Why is the tempo sometimes half or double?

Accepted Answer

A detector reading 150 and a drummer counting 75 are both right; which one you want depends on the genre. The alternatives are listed next to the number so you can take the one that matches how you count.

Question 3

What do peak and average level mean?

Accepted Answer

Peak is the loudest single sample, average is the level over the whole track, both in dBFS where 0 is the ceiling. A master usually peaks near −1 and averages between −14 and −8.

Question 4

Is my file uploaded?

Accepted Answer

No. It is decoded and analysed in your browser; nothing is sent to a server, and nothing is stored.

Key and BPM finder — both numbers in one pass

Questions about the readout