Creating music with Sonic Pi

We are going to make some funky songs on the Raspberry Pi. A Raspberry Pi is a small computer that we can use to create exciting technology. It was created in the UK by the Raspberry Pi Foundation to help young people like you learn how to code.

This small computer features amazing HD (high-definition) quality video and playback, sports high quality audio, and has the ability to play 3D games.

To get going with your Raspberry Pi, you will need to connect cables and add an SD card before logging in.

Step 0: Setting up your Pi

First check that you have all the parts you need to get your Raspberry Pi set up and working:

• Raspberry Pi
• Micro USB power adaptor
• An SD card with Raspbian already set up through NOOBS
• USB keyboard
• USB mouse
• HDMI cable
• A monitor or TV
• Some headphones

Activity checklist:

1. Place the SD card into the slot of your Raspberry Pi. It will only fit one way so be careful not to break the card.

2. Next connect the HDMI cable from the monitor (or TV) to the HDMI port on the Pi and turn on your monitor.

3. Plug in a USB keyboard and Mouse into the USB ports on the Pi.

4. Plug in your headphones to the 3.5mm sound output jack.

5. Plug in the micro USB power supply and you should see some text appear on your screen.

6. When prompted to login type:

   Login: pi
   Password: raspberry
   

7. Once you have logged in, type startx to load the desktop.

Step 1: First sounds with Sonic Pi

Let’s play some sounds.

This is the Sonic Pi application interface; it has three windows. The largest one is for writing your code, and we call it the Programming Panel. The top right hand window is the Output Panel, and it displays information about your program as it runs. Underneath is the third window; this is the ‘Error Panel’, which displays information if there is a problem or a bug with your program.

Activity checklist:

1. Launch Sonic Pi by clicking on the Main Menu, then Education, and then Sonic Pi.

2. Select Workspace 1.

3. Type:

   play 60

4. Click on the play icon at the top of the screen. What happens?

5. What happens if you type pley 60 and click on the play icon?

This is an example of a bug in your code. In later activities, if the error panel displays text you will know that you have a bug that you need to fix. It could be that you have misspelt a word like play.

6. Now type:

play 60
play 67
play 69

7. Click on the play icon at the top of the screen. What happens?

The computer is playing each note in sequence (one after the after), but it is happening so fast that to us they sound like they are playing at the same time.

8. We need to tell the computer to pause between each note. We can do this by typing the following after each play:

sleep 1 

The value entered after the word `sleep` represents time in seconds. Using the value 1 represents one second. What would you type for half a second?

9. Now write a sequence of play and sleep to make a cool-sounding tune!

Step 2: Frère Jacques

Now you have mastered the basics of Sonic Pi, let’s code a tune!

The values that you have been typing after the word play represent notes; in fact, they are MIDI note numbers. This means we can translate songs played on a piano into Sonic Pi!

We are going to code 'Frère Jacques'. The song begins with:

C D E C or 60 62 64 60 in MIDI notes.

Music notes to MIDI note values

C	D	E	F	G	A	B
60	62	64	65	67	69	71

Activity checklist:

1. Select Workspace 2.

2. Type the following code:

play 60
sleep 0.5
play 62
sleep 0.5
play 64
sleep 0.5
play 60
sleep 0.5

3. Now click on the play icon at the top of the screen and it will play the first part of 'Frère Jacques'.

This first section plays twice. How could you repeat it? You could type the same section out again, or we could start to introduce loops to your code.

4. At the top of your code, above the first play 60, type:

2.times do

5. And at the bottom of your code, below sleep 0.5, type:

end

6. Click on the play icon at the top of the screen. What happens?

Let's play this part in Sonic Pi.

In the example below, you can see that some lines of code are indented. This makes it easier to read your code and check for any bugs if it does not work when you press the play button. You can press the space bar twice to indent a line of code.

2.times do
  play 60
  sleep 0.5
  play 62
  sleep 0.5
  play 64
  sleep 0.5
  play 60
  sleep 0.5
end

Things to try

1. Complete the 'Frère Jacques' song by using the table below to translate musical notes into Sonic Pi note values.

   C D E C C D E C

   E F G E F G

   G A G F E C G A G F E C

   C D E C C D E C

2. Create your own tune using the things that you have learned so far.

Step 3: Change the sounds

It's time to make your tune sound more interesting! We can do this by changing the synthesizer sounds it is using. The default Sonic Pi synth is called "pretty_bell".

To use a different synth, you need to add the code: with_synth "name of synth" above the sequence of code you want to use it in.

In this example, "fm" is the name of the synth:

with_synth "fm"
2.times do
  play 60
  sleep 0.5
  play 67
  sleep 0.5
end

Synths to try

"pretty_bell"
"dull_bell"
"beep"
"saw_beep"
"fm"

Activity checklist:

1. At the top of your code, above the 2.times do, add the following:

with_synth "fm"

2. Click on the play icon at the top of the screen.

3. Change the synth, using the list of synths to try above, to find one that you like the sound of.

Step 4: Using functions

Currently, your Sonic Pi version of 'Frère Jacques' is playing in a set key. It always plays the same notes from the same octave. To give your program the ability to use a different set of notes we can use a function.

Functions are a named group of statements. You could put the first part of 'Frère Jacques' in a function like this:

def frere
  play 60
  sleep 0.5
  play 62
  sleep 0.5
  play 64
  sleep 0.5
  play 60
  sleep 0.5
end

You can then call the function to play by typing frere. However, this does not solve our problem of the song not using a different key. Let's solve this problem now!

Activity checklist:

1. Open a new workspace in which to store your code.

2. Let's begin by creating a function for the first part of the song:

   def frere(n)
     play n
     sleep 0.5
     play n + 2
     sleep 0.5
     play n + 4
     sleep 0.5
     play n
   end

   If you press the play button, nothing will happen. You need to call the function underneath by leaving a space and typing frere 60. The value of the parameter n here is 60, but you can change this.

3. Change the value of n by typing frere 40 or frere 80.

   You will hear the tune play in a different key each time.

Step 5: Playing two tunes at the same time

Music often has a repeating backing track, with a separate melody played over the top. So far in Sonic Pi you have played one tune. Let’s try playing two tunes at the same time!

Activity checklist:

1. Click on a new workspace tab.

2. The code we use to play two tunes at the same time needs to be between in_thread do and end.

3. Underneath in_thread do, type your tune. Here I’ve used 'Frère Jacques' from the earlier activity:

   in_thread do
     with_synth "saw_beep"
     2.times do
       play 60
       sleep 0.5
       play 67
       sleep 0.5
     end
   end

This first 'thread' will act as the melody of your music. Underneath, you can type the code for your backing track or baseline.

4. Type:

   in_thread do
     with_synth "pretty_bell"
     30.times do
       play 49
       sleep 1
     end
   end