Check out step_sequencer which is a similar, but not identical, project I made.

Prerequisites

• ruby 2.3
• system depencencies: apt-get install mpg123 lame alsamixer arecord ffmpeg vorbis-tools
• a decent processor. I have an intel i5 and the load is fairly low. But keep in mind that every drum hit opens a thread and tells mpg123 to play a mp3 file.

Install

• clone
• bundle

Usage

• run ruby sounds.rb and read the instructions page that is printed
• try hitting the keys r,f,v,t,g,b,y,h,n (all in the center of the keyboard) to play some drum sounds.

Extending and Customizing

Start with keyma 6162 p.yml.

To define 'sound effects', work in the lib/effects.rb file. You can call these method from the keymap file

To add mp3 sounds, save the files into the mp3/ folder. If you call play('hihat') from code that will look for mp3/hihat.mp3.

When the CLI is running, all keystrokes are interpreted as musical hits with two exceptions:

• control+c will exit
• / begins a 'special command'

See lib/special_commands.rb for reference, but here are some examples:

• /r turns on/off recording
• /p turns on/off looped playback of the last recorded sound
• /u turns on/off metronome
• /td launches a prompt to decrease the tempo (for metronome)
  • /tu and /t= work similarly
• /s prompts for a new time signature (used by metronome)
• /h prints the help page
• /k prints the keymap

Feaures in development

Arpeggios:

• see the keymap for an example of starting an arpeggio.
• define a new arpeggio in lib/arpeggio_scales.rb. Also see Integer#to_musical_scale_step defined in core_util.rb and the methods in lib/musical_scale_step.rb.
• The first time an arpeggio is run, it will create a bunch of files. These are copies of the trigger mp3 sound, pitch shifted to whatever the arpeggio requires.
• From time to time rm -rf mp3/arpeggios/* can be run to clear out old arpeggio files if the folder's getting large. The arpeggio files can be recreated at runtime, anyway.