major scale

pure_tone.rb

@@ -0,0 +1,41 @@
+require 'rubygems'
+require 'fftw3'
+require 'ruby-audio'
+
+require "util"
+
+def make_tone( frequency = 440.0, duration = 1.0, frames_per_second = 44100 )
+  cycles_per_tau = frames_per_second / frequency.to_f
+  tau = Math::PI * 2
+  step = tau / cycles_per_tau
+
+  (frames_per_second * duration).to_i.times do |n|
+    yield Math.sin(n * step)
+  end
+end
+
+# 0 A
+# 1 A#
+# 2 B
+# 3 C
+# 4 C#
+# 5 D
+# 6 D#
+# 7 E
+# 8 F
+# 9 F#
+# 10 G
+# 11 G#
+
+result_buffer = RubyAudio::Buffer.new("float", 44100 * 13, 1)
+i = 0
+[3,5,7,8,10,12,14,15].each do |note|
+  f = 220 * (2 ** (note/12.0))
+  p f
+  make_tone(f) do |val|
+    result_buffer[i] = val
+    i += 1
+  end
+end
+info = RubyAudio::SoundInfo.new :channels => 1, :samplerate => 44100, :format => RubyAudio::FORMAT_WAV|RubyAudio::FORMAT_PCM_16
+buffer_to_file(result_buffer, "beep.wav", info)