How to get BPM of song?

Unity Engine
1

I want get number BPM of song with input is song.
Input: “Audio.mp3”
output: number BPM

Please help me!!!

2

You’ll need to look into making an FFT system - which is pretty complex:

3

I use library “bpmDetect.dll” to get value BPM. (Copy file “bpmDetect.dll” to folder “Asset\plugins”). But unusable. Code follow:

1126196--42555--$pic.png
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Documentation about “bpmDetect.dll”: http://adionsoft.net/bpm/index.php?module=docs

Why? pls