One liner music player for Ruby. http://hitode909.appspot.com/one-liner-music/

olm.rb

require 'rubygems'
require 'ffi-portaudio'

def safe
  r = nil
  Thread.new {
    $SAFE = 4
    r = yield
  }.join
  r
end

class OLMStream < FFI::PortAudio::Stream
  attr_accessor :generator

  def initialize
    @count = 0
    @max = 1
  end

  def process(input, output, frameCount, timeInfo, statusFlags, userData)
    wave = (0...frameCount).map{|i|@generator.call(@count+=1) % 255}
    @max = [wave.max, @max].max
    volume = 0x8000.quo @max
    output.write_array_of_int16 wave.map!{|v| v * volume}

    :paContinue
  end
end

include FFI::PortAudio


def create_music(generator)
  fork do
    API.Pa_Initialize

    output = API::PaStreamParameters.new
    output[:device] = API.Pa_GetDefaultOutputDevice
    output[:channelCount] = 1
    output[:sampleFormat] = API::Int16
    output[:suggestedLatency] = 0.2
    output[:hostApiSpecificStreamInfo] = nil

    s = OLMStream.new
    s.generator = safe { eval "lambda {|t| #{generator} }" }
    s.open(nil, output, 8000)
    s.start

    at_exit do
      s.close
      API.Pa_Terminate
    end

    loop { sleep 1 }
  end
end

ARGV.each do |generator|
  create_music(generator)
end

loop { sleep 1 }