binary black sheep do you have any wool?

baba.sonicpi.rb

# CDEFGABC
the_song = <<-BA_BA_BLACKSHEEP
10000000
10000000
00001000
00001000
00000100
00000100
00001000
00001000
00010000
00010000
00100000
00100000
01000000
01000000
10000000
BA_BA_BLACKSHEEP

def read_notes(ones_and_zeros)
  note_map = [:C3,:D3,:E3,:F3,:G3,:A3,:B3,:C4]
  notes = ones_and_zeros.each_with_index.collect do |one_or_zero, index |
    if one_or_zero == '1'
      note_map[index]
    end
  end
  notes.select { |note| note }
end


def play_song(song, params)
  speed = params[:speed] || 4.0
  song.each_line do |line|
    play_chord read_notes(line.strip.each_char), release: (1.0/speed)
    sleep (1.0/speed)
  end
end

def song_duration(song, params)
  speed = params[:speed] || 4.0
  song.strip.split.length * (1.0/speed)
end

print song_duration the_song, :speed => 2
with_fx :distortion do
  play_song the_song, :speed => 4
end

Nice work! I really like how you've effectively created a tracker interface just using 0's and 1's!

Just wanted to say that Sonic Pi has a define method which behaves a lot like def. It's best to use that to make sure Sonic Pi can do all the optimisations it needs to. Not a big deal in this example but it helps when you're doing more complex stuff :)