Ruby is used for a lot of things, but for some reason, only a few people are using it for music. In a language that is meant to make programming fun, the lack of such creative code is scary. Let's fix the current landscape by learning how to use the tools available in Ruby (and some not) to let those creative juices flow. We will be focusing on how to build sounds from the ground up (the powerful amplitude, and the majestic waveform), so you don't need any prior audio wizardry. Just bring yourself and a Ruby console and we just might create some beautiful music in a beautiful language.

1. It’s so quiet.
Let’s make music.
Loren Segal
RubyConf 2014

2. @lsegal

3. WARNING:
MUSIC
AHEAD
 

4. What is
music
even?

5. S + R = M
ound
hythm
usic

6. S + R = M
ound
hythm
usic

7. S + R = M
ound
uby
usic

8. S + R =
ound
uby

9. S + R =
ound
uby
This talk.

10. Sounddd beep.
boop.

11. Analog
Audio

12. Good Vibrations

13. Continuous Signal

14. DIGITAL
AUDIO

15.  ? 

16. Discrete Signal (not continuous)
187
198
-84 -84

17. not continuous,
Just Samples

18. Discrete Signal (not continuous)

19. Discrete Signal (not continuous)

20. Discrete Signal (sampling)

21. Discrete Signal (sampling)

22. Discrete Signal (sampling)

23. Audio Vocabulary
[Sample Rate]⇒
“Number of data values for
each second of audio”
Measured in Hertz (Hz)

24. 20 Samples
20.times.map {|i| (Math.sin(i) * 255).floor }
[0, 214, 231, 35, -193,
-245, -72, 167, 252, 105,
-139, -255, -137, 107, 252,
165, -74, -246, -192, 38]

25. Common Sample Rates
44,100 Hz
44,800 Hz
96,000 Hz
used by VHS, CDs

26.  

27. fundamental
WAVES

28. SINE
sin(x)

29. #math

31. f(t) = A sin(2πΩt)
s

32. f(t) = A sin(2πΩt)
Amplitude
Frequency
s

33. Amplitude
Frequency*
…ish

34. Audio Vocabulary
[Amplitude]⇒
“Loudness”
Measured in Decibels (dB)

35. Audio Vocabulary
[Frequency]⇒
“Pitch”
Measured in Hertz (Hz)

36. Ωs
s = Sample Rate
= e.g., 44100

37. Frequency?

38. Ω = 440 Hz [A3]

39. f(t) = sin(0.0627t)

41. SQUARE

42. f(t) = A ((Ωt) < 0.5 ? -1 : 1) s

43. Triangle

44. f(t) = A(1 - 4(Ωst - Ωst ))

45. SAW(tooth)

46. f(t) = 2A (Ωt - Ωt ) s s

47. NOISE

48. f(t) = A rand()
rand() = some evenly distributed random fn

49. Show,
Don’t Tell

50. Processing
Audio

51. From
synthesis

52. To
analysis

53. Fourier
Transform

54. It’s Complex

55. Literally.

56. SIDE VIEW OF f(t)!

57. thefouriertransform.com

58. “All waveforms, no matter what you
scribble or observe in the universe,
are actually just the sum of simple
sinusoids of different frequencies.”

64. Analysis
Applications

65. 1.
Pitch Detection:
Instrument Tuner,
Visualization

66. 2.
Wave Shaping:
Equalizer,
Autotune

67. Let’s see it.

68. RUBY
TIME

69. ruby-audio $ gem install

70. libsndfile
wrapper

71. Write a Sine Wave
require
'ruby-­‐audio'
include
RubyAudio
sample_rate,
len,
freq,
amp
=
48000,
10,
440,
0.9
buf
=
Buffer.float(sample_rate
*
len)
buf.size.times
do
|i|
sine_rad
=
((freq
*
Math::PI
*
2)
/
sample_rate)
*
i
buf[i]
=
amp
*
Math.sin(sine_rad)
end
format
=
FORMAT_WAV
|
FORMAT_PCM_16
info
=
SoundInfo.new(channels:
1,
samplerate:
sample_rate,
format:
format)
snd
=
Sound.new('out.wav',
'w',
info)
snd.write(buf)
snd.close

72. easy_audio $ gem install

73. portaudio
wrapper

74. Play a Sine Wave
require
'easy_audio'
EasyAudio.easy_open(&EasyAudio::Waveforms::SINE)
sleep
2
#
play
for
2
seconds

75. Increase Frequency / Time
require
'easy_audio'
triangle
=
EasyAudio::Waveforms::TRIANGLE
stream
=
EasyAudio.easy_open(freq:
220,
&triangle)
Thread.new
{
loop
{
stream.frequency
+=
50;
sleep
0.2
}
}
sleep
3

76. Audio
Plugins

77. VST

78. github.com/lsegal/ easy_vst

79. Embedding DRb - C++
AudioEffect*
createEffectInstance(audioMasterCallback
audioMaster)
{
ruby_init();
ruby_init_loadpath();
rb_require("drb/drb");
rb_eval_string("DRb.start_service");
return
new
SampleVST(audioMaster);
}
//
...
server
=
rb_eval_string(
"DRbObject.new_with_uri('druby://localhost:9090')");

80. Call Distributed Method
rb_funcall(
server,
//
the
DRb
object
rb_intern(“process”),
//
the
remote
method
1,
//
one
argument
INT2FIX(sampleFrames));
//
number
of
samples

81. Fun
Time!

82. Summary

83. 1. Audio is samples!

84. 2. Making waves!
Sine, Square,
Saw, Triangle,
Noise

85. 3. Fourier = analysis

86. 4. Ruby libraries!
ruby-audio
easy_audio
easy_vst

87. 5. Music!

88. 
gnuu.org

89. github.com/lsegal

90. @lsegal

91. Thanks! Questions?