scissor_stretch_demo.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'pit'
require 'scissor/echonest'

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

infile, outfile = ARGV
beats = Scissor(infile).beats
result = Scissor()

until beats.empty?
  some_beats = beats.shift(rand(5) + 1)
  duration = some_beats.inject(0) do |total, b|
    total + b.duration
  end

  result += some_beats[0].stretch((duration / some_beats[0].duration.to_f) * 100)
end

result >> outfile