ruby/sample/trick2013/mame/remarks.markdown

1.5 KiB

Remarks

Run the program under a platform that /dev/dsp is available. For example, if you are using pulseaudio, use padsp:

padsp ruby entry.rb

Please see Limitation if you want to run this program on os x.

I confirmed the following platforms.

  • ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-linux]
  • ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]
  • ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin10.8.0]

For those who are lazy, I'm attaching a screencast.

Description

This program is a music-box quine. It prints itself with playing "Jesu, Joy of Man's Desiring".

Internal

Like a real music box, this program consists of a mechanical part (code) and a piano roll. In the piano roll, # represents a pin that hits a note, and | represents a slur. The leftmost column corresponds 110Hz (low A). Every column corresponds a semitone higher than the left one.

This program uses the frequency modulation synthesis to play the sound like a music-box. You can create a different-sounding tone by changing the parameter. For example, the following will play the sound like a harpsichord.

padsp ruby entry.rb 2.0

Note that this program does not use an idiom to remove whitespace, such as .split.join. All newlines and spaces do not violate any of the Ruby syntax rules.

Limitation

On os x, /dev/dsp is not available. You have to use sox by replacing the following part:

open("/dev/dsp","wb")

with:

IO.popen("./pl","wb")