bpm

Library and tool for dealing with beats per second detection in Go

This is a direct port of Mark Hills bpm-tools.

For that reason, it is also under the same licence as that utility, ( GPLv2 ).

You can use this version as a libary too, In testing you may find it produces slightly different results than bpm-tools. This is because both tools use a random float on mid point selection, Ideally it would use a static one, but I won't replicate drand exactly to just get 1:1 matching with the offical tools.

Usage of the command line util

You need to feed the command line utility PCM 32 bit little edian floats (mono), there are two easy ways to do this:

Sox:

sox "$FILE" -r 44100 -e float -c 1 -t raw - | ./cmd /dev/stdin

ffmpeg:

ffmpeg -v quiet -i 1479012090.ts -f f32le -ac 1 -c:a pcm_f32le -ar 44100 pipe:1 | ./cmd /dev/stdin

You can also ask for a "snapshot" per second of the BPM calculated, using progressive mode:

$ ffmpeg -v quiet -i 1479012090.ts -f f32le -ac 1 -c:a pcm_f32le -ar 44100 pipe:1 | ./cmd -progressive=true /dev/stdin
179.020979
193.086109
191.044776

The first value is the BPM for the first 10 seconds, the 2nd for 10-20 seconds, 3rd is the 20-30th (and more until you stop giving it data)