flatten.rb

#!/usr/bin/env ruby                                                                                                                                                                                              
require 'rubygems'
require 'pit'
require 'scissor/echonest'

config = Pit.get('echonest.com', :require => {
    'api_key' => 'your Echo Nest API key'
  })

Scissor.echonest_api_key = config['api_key']
Scissor.logger.level = Logger::DEBUG

def main
  if ARGV.size != 2
    puts "usage: #$0 srcfile outfile"
    exit
  end

  flatten(ARGV[0]) >> ARGV[1]
end

def avarage_duration(chunks)
  chunks.inject(0) do |total, chunk|
    total + chunk.duration
  end / chunks.size.to_f
end

def flatten(srcfile)
  beats = Scissor(srcfile).beats
  avarage_duration = avarage_duration(beats)

  Scissor.join(beats.map do |beat|
    beat.pitch(beat.duration / avarage_duration * 100)
  end)
end

main