# Bizet Beats

After our brief excursion to the fantastic world of coding Minecraft with Sonic Pi last month, let’s get musical again. Today we’re going to bring a classical operatic dance piece straight into the 21st century using the awesome power of code.

# Outrageous and Disruptive

Let’s jump into a time machine back to the year 1875. A composer called Bizet had just finished his latest opera Carmen. Unfortunately like many exciting and disruptive new pieces of music people initially didn’t like it at all because it was too outrageous and different. Sadly Bizet died ten years before the opera gained huge international success and became one of the most famous and frequently performed operas of all time. In sympathy with this tragedy let’s take one of the main themes from Carmen and convert it to a modern format of music that is also too outrageous and different for most people in our time - live coded music!

# Decoding the Habanera

Trying to live code the whole opera would be a bit of a challenge for this tutorial, so let’s focus on one of the most famous parts - the bass line to the Habanera:

This may look extremely unreadable to you if you haven’t yet studied music notation. However, as programmers we see music notation as just another form of code - only it represents instructions to a musician instead of a computer. We therefore need to figure out a way of decoding it.

# Notes

The notes are arranged from left to right like the words in this magazine but also have different heights. The height on the score represents the pitch of the note. The higher the note on the score, the higher the pitch of the note.

In Sonic Pi we already know how to change the pitch of a note - we either use high or low numbers such as `play 75` and `play 80` or we use the note names: `play :E` and `play :F`. Luckily each of the vertical positions of the musical score represents a specific note name. Take a look at this handy look up table:

# Rests

Music scores are an extremely rich and expressive kind of code capable of communicating many things. It therefore shouldn’t come as much of a surprise that musical scores can not only tell you what notes to play but also when not to play notes. In programming this is pretty much equivalent to the idea of `nil` or `null` - the absence of a value. In other words not playing a note is like the absence of a note.

If you look closely at the score you’ll see that it’s actually a combination of black dots with lines which represent notes to play and squiggly things which represent the rests. Luckily Sonic Pi has a very handy representation for a rest: `:r`, so if we run: `play :r` it actually plays silence! We could also write `play :rest`, `play nil` or `play false` which are all equivalent ways of representing rests.

# Rhythm

Finally, there’s one last thing to learn how to decode in the notation - the timings of the notes. In the original notation you’ll see that the notes are connected with thick lines called beams. The second note has two of these beams which means it lasts for a 16th of a beat. The other notes have a single beam which means they last for an 8th of a beat. The rest has two squiggly beams which means it also represents a 16th of the beat.

When we attempt to decode and explore new things a very handy trick is to make everything as similar as possible to try and see any relationships or patterns. For example, when we re-write our notation purely in 16ths you can see that our notation just turns into a nice sequence of notes and rests.

# Re-coding the Habanera

We’re now in a position to start translating this bass line to Sonic Pi. Let’s encode these notes and rests in a ring:

    (ring :d, :r, :r, :a, :f5, :r, :a, :r)

Let’s see what this sounds like. Throw it in a live loop and tick through it:

    live_loop :habanera do
      play (ring :d, :r, :r, :a, :f5, :r, :a, :r).tick
      sleep 0.25
    end

Fabulous, that instantly recognisable riff springs to life through your speakers. It took a lot of effort to get here, but it was worth it - high five!

# Moody Synths

Now we have the bass line, let’s re-create some of the ambience of the operatic scene. One synth to try out is `:blade` which is a moody 80s style synth lead. Let’s try it with the starting note `:d` passed through a slicer and reverb:

    live_loop :habanera do
      use_synth :fm
      use_transpose -12
      play (ring :d, :r, :r, :a, :f5, :r, :a, :r).tick
      sleep 0.25
    end
    with_fx :reverb do
      live_loop :space_light do
        with_fx :slicer, phase: 0.25 do
          synth :blade, note: :d, release: 8, cutoff: 100, amp: 2
        end
        sleep 8
      end
    end

Now, try the other notes in the bass line: `:a` and `:f5`. Remember, you don’t need to hit stop, just modify the code whilst the music is playing and hit run again. Also, try different values for the slicer’s `phase:` opt such as `0.5`, `0.75` and `1`.

# Bringing it all together

Finally, let’s combine all the ideas so far into a new remix of the Habanera. You might notice that I’ve included another part of the bass line as a comment. Once you’ve typed it all into a fresh buffer hit Run to hear the composition. Now, without hitting stop, uncomment the second line by removing the `#` and hit run again - how marvellous is that! Now, start mashing it around yourself and have fun.

    use_debug false
    bizet_bass = (ring :d, :r, :r, :a, :f5, :r, :a, :r)
    #bizet_bass = (ring :d, :r, :r, :Bb, :g5, :r, :Bb, :r)

    with_fx :reverb, room: 1, mix: 0.3 do
      live_loop :bizet do
        with_fx :slicer, phase: 0.125 do
          synth :blade, note: :d4, release: 8,
            cutoff: 100, amp: 1.5
        end
        16.times do
          tick
          play bizet_bass.look, release: 0.1
          play bizet_bass.look - 12, release: 0.3
          sleep 0.125
        end
      end
    end

    live_loop :ind do
      sample :loop_industrial, beat_stretch: 1,
        cutoff: 100, rate: 1
      sleep 1
    end

    live_loop :drums do
      sample :bd_haus, cutoff: 110
      synth :beep, note: 49, attack: 0,
        release: 0.1
      sleep 0.5
    end