Make a song
Great! Now you got your song running nicely with a steady beat and a bass with the melody hook on the top. Now we’re going to do something really cool and unleash the true potential of Sonic Pi. Let’s add some generative elements to the track and program the computer to compose for us!
Transposing means changing the pitch up or down. We could randomly transpose the melody a bit every now and then to add some spice to the track. You can throw a dice to decide when to shift the pitch up for the melody. Here’s an example:
Let’s do something interesting for the bass loop.
.choose is a handy method that randomly picks out an element from a list. Like this:
[:c, :e, :g] is a list of notes (in this case the notes of the C major chord).
.choose picks out one of those notes at random. Instead of notes you could have anything in the list. Like sleep values for example:
You don’t even have to remember what notes are in what chords. Sonic Pi can handle that for you. Instead of writing
[:c, :e, :g], you can just use
(chord :C, :major). That creates a list of right notes for you automatically. Here’s an example:
Let’s use this sorcery for a bubbling bass track. Save your work and copy your current
:bass loop to another buffer, in case you want to come back to it. Then make room for our new bass track and delete the content of the loop. Let’s use the classic
:tb303 synth and play random 16th notes from C major chord:
Ough! Not quite right. Add
, release: 0.125 parameter in the end of the play command, like this:
That’s better, but there’s still a bit polishing to do. So far you have used the
release: parameters for a play command. Depending on the synth you are using, there’s a lot lot more parameters to use. For example the tb303 synth has 45 different options to tweak. Let’s use a parameter called
cutoff for the bass. Cutoff removes all frequencies above the cutoff frequency. You can use values between 0-130.
But don’t just use a fixed cutoff value when you can have a random value! With
rrand(min, max) you can generate random numbers in a given range. Try that out:
Grrreat! Remember to explore and try out different things. As a recap, here’s an example about what you could have going on at this point: