# BPM and key detection
Source: https://docs.aden.space/docs/help/make-music/audio-analysis

Every dropped or uploaded audio file gets its tempo, key, length and waveform read on the device, off the main thread, by Aden's own audio core in WebAssembly.
{/* Generated by `bun docs:publish` from docs/features/audio-analysis.md: edit the spec, not this file. */}

## What it is [#what-it-is]

When you add audio to Aden, it reads the tempo (BPM), the musical key, the
length and the waveform for you. It all happens on your computer: the file is
analyzed before it finishes uploading, and nothing is sent anywhere to do it.

## Using it [#using-it]

* **New track, new version, bulk upload, playlist import**: drop the files.
  BPM and key fill in by themselves. On New track, a BPM or key you typed, or
  one in the file name ("Afterglow 124 Am.wav"), wins over the detected one.
* **Analyze again**: on a version, **Analyze BPM and key** in its menu reads
  the file again.
* **Key finder**: drop or record a track at `aden.space/key` to see its key
  over time and its chords.
* Silence, a pad without a beat, or a few seconds of sound get no BPM rather
  than a guess. Edit any value by hand.