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 :saw
  
  lowcut = note(:E1) # ~ 40Hz
  highcut = note(:G8) # ~ 3000Hz
  
  note = [40, 41, 28, 28, 28, 27, 25, 35].choose
  
  duration = 2
  bpm_scale = (60 / current_bpm).to_f
  
  distort = 0.5
  
  # scale the note length based on current tempo
  slide_duration = duration * bpm_scale
  
  puts "lowcut: #{lowcut}"
  puts "slide_duration #{slide_duration}"
  
  # 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|
      
      ##| puts "synth_node: #{synth_node.ctl}"
      ##| puts "c.ctl: #{c.ctl}"
      ##| puts "c: #{c}"
      
      ##| synth :synth_node, note: note, attack: 0, sustain: duration, release: 0
      play note: note - 12, sustain: duration, release: 0, amp: 0.5
      play note: note, sustain: duration, release: 0.125, amp: 0.5
      play note: note + 12, sustain: duration, release: 0, amp: 0.5
      play note: note + 24, sustain: duration, release: 0, amp: 0.5
      
      # 6/4 rhythms
      wobble_time = [1, 6, 6, 2, 1, 2, 4, 8, 3, 3, 16].choose
      
      ##| sleep 1
      c.ctl cutoff_slide: ((duration / wobble_time.to_f) / 2.0)
      ##| synth :synth_node, 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
        wobble_low = duration / wobble_time.to_f
        ##|   puts "wobble sleep time: #{((duration / wobble_time.to_f) / 2)}"
        c.ctl cutoff: lowcut
        sleep wobble_low / 2.0
        c.ctl cutoff: highcut
        sleep wobble_low / 2.0
      end
    end
  end
end

in_thread(name: :wob) do
  with_fx :reverb, room: 0.8, mix: 0.5 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