Live Coding

Now we’ve learned enough to really start having some fun. In this section we’ll draw from all the previous sections and show you how you can start making your music compositions live and turning them into a performance. For that we’ll need 3 main ingredients:

An ability to write code that makes sounds - CHECK!
An ability to write functions - CHECK!
An ability to use (named) threads - CHECK!

Alrighty, let’s get started. Let’s live code our first sounds. We first need a function containing the code we want to play. Let’s start simple. We also want to loop calls to that function in a thread:

define :my_sound do
  play 50
  sleep 1
end

in_thread(name: :looper) do
  loop do
    my_sound
  end
end

If that looks a little too complicated to you, go back and re-read the sections on functions and threads. It’s not too complicated if you’ve already wrapped your head around these things.

What we have here is a function definition which just plays note 50 and sleeps for a beat. We then define a named thread called :looper which just loops around calling my_sound repeatedly.

If you run this code, you’ll hear note 50 repeating again and again…

Changing it up

Now, this is where the fun starts. Whilst the code is still running change 50 to another number, say 55, then press the Run button again. Woah! It changed! Live!

It didn’t add a new layer because we’re using named threads which only allow one thread for each name. Also, the sound changed because we redefined the function. We gave :my_sound a new definition. When the :looper thread looped around it simply called the new definition.

Try changing it again, change the note, change the sleep time. How about adding a use_synth statement? For example, change it to:

define :my_sound do
  use_synth :tb303
  play 50, release: 0.3
  sleep 0.25
end

Now it sounds pretty interesting, but we can spice it up further. Instead of playing the same note again and again, try playing a chord:

define :my_sound do
  use_synth :tb303
  play chord(:e3, :minor), release: 0.3
  sleep 0.5
end

How about playing random notes from the chord:

define :my_sound do
  use_synth :tb303
  play choose(chord(:e3, :minor)), release: 0.3
  sleep 0.25
end

Or using a random cutoff value:

define :my_sound do
  use_synth :tb303
  play choose(chord(:e3, :minor)), release: 0.2, cutoff: rrand(60, 130)
  sleep 0.25
end

Finally, add some drums:

define :my_sound do
  use_synth :tb303
  sample :drum_bass_hard, rate: rrand(0.5, 2)
  play choose(chord(:e3, :minor)), release: 0.2, cutoff: rrand(60, 130)
  sleep 0.25
end

Now things are getting exciting!

However, before you jump up and start live coding with functions and threads, stop what you’re doing and read the next section on live_loop which will change the way you code in Sonic Pi forever…