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A command-line drum machine. Convert a beat notated in YAML into a *.wav file.
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Beats Drum Machine

Beats is a command-line drum machine written in pure Ruby. Feed it a song notated in YAML, and it will produce a precision-milled *.wav file of impeccable timing and feel. Here's an example song:

  Tempo: 105
    - Verse:  x4
    - Chorus: x4
    - bass:     house_2_1.wav
    - snare:    roland_tr_909_2.wav
    - hihat:    house_2_5.wav
    - cowbell:  big_beat_5.wav
    - deep:     house_2_2.wav

  - bass:     X..X...X..X.....
  - snare:    ....X.......X...
  - hihat:    ..X...X...X...X.

  - bass:     X..X...X..X.....
  - snare:    ....X.......X...
  - hihat:    XXXXXXXXXXXXX...
  - cowbell:  ....XX.X..X.X...
  - deep:     .............X..

And here's what it sounds like after getting the Beats treatment. What a glorious groove!

For more, check out


To install the latest stable version (2.1.1) from, run the following from the command line:

gem install beats

Note: if you're installing using the default version of Ruby that comes with macOS, you might get a file permission error. If that happens, use sudo gem install beats instead. If you're using a version manager such as rbenv, chruby, or RVM, plain gem install beats should work fine.

Once installed, you can then run Beats from the command-line using the beats command.

Beats is not very useful unless you have some sounds to use with it. You can download some example sounds from


Beats runs from the command-line. Run beats -h to see the available options. For more detailed instructions, visit on the Beats Wiki.

Check out this tutorial at to see an example of how to create a beat from sratch.

What's New in v2.1.1

The latest version of Beats is 2.1.1, released on June 29, 2018. It contains these changes:

  • Several error messages are improved to be more accurate or specific.

  • Bug fix: Songs can now use *.wav files with more than 2 channels. Previously, using a sound with more than 2 channels would cause a fatal Invalid sample data array in AudioUtils.normalize() error.

  • Bug fix: If a sound is defined multiple times in a Kit, the final definition should be used as the winner. However, previously this did not occur if the earlier definition was for a composite sound. For example, with this Kit:

      - sound: [sound1.wav, sound2.wav]
      - sound: sound3.wav

    sound will now be bound to sound3.wav, not [sound1.wav, sound2.wav].

For info about previous releases, visit

Local Development

First, install the required dependencies:

bundle install

To run Beats locally, use bundle exec and run bin/beats, to avoid using any installed gem executable. For example:

bundle exec bin/beats -v

To run the tests:

bundle exec rake test

Found a Bug? Have a Suggestion? Want to Contribute?

Contact me (Joel Strait) by sending a GitHub message or opening a GitHub issue.


Beats Drum Machine is released under the MIT license.

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