Auto generating dubstep with Sonic Pi

auto_dubstep.rb

# DUBSTEP
# Combines ideas from my other gists
current_bpm = 140.0 
use_bpm current_bpm

# WOBBLE BASS 
define :wob do
  use_synth :dsaw
  lowcut = note(:E1) # ~ 40Hz
  highcut = note(:G8) # ~ 3000Hz
  
  note = [40, 41, 28, 28, 28, 27, 25, 35].choose
  
  duration = 2.0
  bpm_scale = (60 / current_bpm).to_f
  distort = 0.2
  
  # scale the note length based on current tempo
  slide_duration = duration * bpm_scale
  
  # Distortion helps give crunch
  with_fx :distortion, distort: distort do
  
    # rlpf means "Resonant low pass filter"
    with_fx :rlpf, cutoff: lowcut, cutoff_slide: slide_duration do |c|
      play note, attack: 0, sustain: duration, release: 0
 
      # 6/4 rhythms
      wobble_time = [1, 6, 6, 2, 1, 2, 4, 8, 3, 3, 16].choose
      c.ctl cutoff_slide: ((duration / wobble_time.to_f) / 2.0)
 
      # Playing with the cutoff gives us the wobble!
      # low cutoff    -> high cutoff        -> low cutoff
      # few harmonics -> loads of harmonics -> few harmonics
      # wwwwwww -> oooooooo -> wwwwwwww
      # 
      # N.B.
      # * The note is always the same length *
      # * the wobble time just specifies how many * 
      # * 'wow's we fit in that space *
      wobble_time.times do
        c.ctl cutoff: highcut
        sleep ((duration / wobble_time.to_f) / 2.0)
        c.ctl cutoff: lowcut 
        sleep ((duration / wobble_time.to_f) / 2.0)
      end
    end
  end
end
 
in_thread(name: :wob) do
  with_fx :reverb, mix: 0.1 do
    loop do
      wob
    end
  end
end

# FUNKY DRUMS
ghost = -> { rrand(0.1, 0.2) }
normal = -> { rrand(0.5, 0.6) }
accent = -> { rrand(0.8, 0.9) }

swing_time = 0.05
puts swing_time

define :play_kick do
 sample :elec_hollow_kick
 play :A1
end

in_thread(name: :beat) do
  loop do
    # Two ways of modelling beats - with 0s and 1s OR with indexes
    [1, 0, 0, 0, 0, 0, 1, 0].each.with_index(1) do |kick, index|
      play_kick if kick == 1
      
      if [1,3,4,5,7,8].include? index
        # Rand here can be really nice
        sample :drum_cymbal_closed, amp: ((index % 2) == 0 ? ghost.call : normal.call ) if rand < 0.8
      end
      
      with_fx :reverb, mix: 0.5 do
        # Always have snare on 2 and 4
        if index == 5
          sample :drum_snare_hard, amp: normal.call
        end
      end
      
      # And sometimes on the and of 4
      if (index % 2) == 0
        sample :drum_snare_soft, amp: ghost.call if rand < 0.05
      end

        
      if(index % 2) == 0
        # offbeats need to be slightly late for swing
        sleep (0.5 - swing_time)
      else
        sleep (0.5 + swing_time)
      end
    end
  end
end

# SAMPLES
in_thread(name: :beat) do
  loop do
    with_fx :echo, rate: 1 do
      with_fx :rlpf, cutoff: rrand(80, 120) do
        sample [:ambi_haunted_hum, :ambi_piano].choose, rate: [0.25, 0.5, 1, 2].choose if rand > 0.1
        sleep 4
      end
    end
  end
end

Your drum and sample threads are both named :beat, so only one of them runs (the second one for me, not sure why). Renaming one to :beat2 allows both to be heard. Very cool!

This is pretty awesome! How long did it take you to figure out how to write this?

Wow, just ran across and it still works on the latest Sonic Pi. I was tempted to try SoundCollider to emulate dubstep sounds but this is pretty much what I was looking for. So many tricks in here! 🤯