puffy 13~> bpm -h
bpm (C) Copyright 2013 Mark Hills <mark@xwax.org>

Usage: bpm [options]
Analyse the tempo (in beats-per-minute, BPM) of incoming audio

  -g <path>  Output autodifference data to file
  -e <path>  Output energy data to file
  -f         Print format for final BPM value (default %0.1f)
  -m <f>     Minimum detected BPM (default 84)
  -x <f>     Maximum detected BPM (default 146)
  -v         Print progress information to stderr
  -h         Display this help message and exit

Incoming audio is raw audio on stdin at 44100Hz, mono, 32-bit float; eg.
  $ sox file.mp3 -t raw -r 44100 -e float -c 1 - | ./bpm

To view autodifference or energy data:
  $ sox [...] | bpm -g file.dat
  $ gnuplot
  gnuplot> plot file.dat