This is a code library I'm building to support my musical efforts with Sonic Pi. These efforts are currently in the following categories:

• Use Sonic Pi as a synthesizer to control via my MIDI-equipped electric mandolin.
• Experiment with different sound synthesis techniques.
• Encode melodies as data structures and play them back with a variety of synthesized sounds.

Of course, you'll need to adjust the path to where you installed it on your machine, but this is the general idea.

run_file "~/Documents/sonic_pi_songs/my_funcs.rb"

I have written several simple sound synthesis functions which all have a common API. The first parameter is the note to play. The second parameter is the amp value, defaulting to 1. These functions, in turn, are passed as parameters to the other functions in this framework.

Some examples include:

• blade_swell
• cool_tri
• additive_1

The play_melody function takes two parameters:

• note_times_list: A list in which each element is a list containing a note, a duration, and (optionally) an amplitude. If no amplitudes are supplied, it will use an amplitude of 1.
• note_maker: A sound synthesis function.

It then plays the given melody with the given sound. The program joy_to_the_world.rb is an example of its use.

Additional melody playback functions, using the same parameters:

• play_harmonized_melody: Auto-detects the scale used and plays back a melody harmonized in thirds with the detected scale.

I'm using the Sonuus i2M Musicport to convert my mandolin playing into MIDI instructions. It issues three types of MIDI messages:

• note_on note volume
• note_off note 0
• pitch_bend amount

The basic live_loop MIDI function is midi_loop. It expects two parameters:

• A sound synthesis function.
• A function describing what to do before sounding the note.

So far, I've written the following live_loop functions as MIDI event handlers:

• basic_midi_loop: Handles each note_on event by activating a sound synthesis function, specified by the note_maker parameter.
• midi_drone_loop: Similar to basic_midi_loop, but it accompanies each melody note with a specified drone note. The drone note can have a separate sound and has a scaling factor to control its volume. Useful for playing many medieval melodies.
• midi_harmonizer_loop: Similar to basic_midi_loop, augmented with harmony notes, determined by the scale and interval parameters. The interval is the position in an octave, so if interval is 3 it will harmonize in thirds.
• midi_sampler: This function allows a user to play a MIDI instrument (its sound specified by the note_maker parameter), recording the melody, until the amount of time given by the replay_delay parameter has passed. At that point, it will play an interpretation of the melody as specified by the player function.
  • Every player function has to have the same two parameters as play_melody
    • note_times_list
    • note_maker
  • Every function listed in the Melody Playback section can be used as a player function.

run_file "~/Documents/sonic_pi_songs/my_funcs.rb"

basic_midi_loop :blade_swell

This program loads in my library, then starts up a basic_midi_loop using the blade_swell synthesizer sound.

run_file "~/Documents/sonic_pi_songs/my_funcs.rb"

midi_sampler :additive_1, :play_harmonized_melody, 1.5

This program loads in my library, then starts up a midi_sampler that will record a melody using the additive_1 synthesizer sound until there is a rest of 1.5 beats. At that point, it will play the melody back using that same sound, accompanied by a harmony melody a third higher.