Playing with Sonic Pi

14 June 2016

musicraspberry-pi

There are several ways to play notes using sonic pi, not all of them obvious from the start.

Single Notes

Single notes are played using the play function but the arguments can be formulated in a couple of different ways.

First, there’s the obvious one, found in all the tutorials, where you define the note to play using an integer value:

play 60
sleep 0.5

This plays a middle C for half a second. Note values can also be described using ruby symbols. Here’s the same note, middle C, using a symbol that defines the note name and the octave:

play :C5
sleep 0.5

Note that incidentals are available, sharps use an ‘s’ in between the note name and the octave, flats use a ‘b’.

play :Cs5
sleep 0.5
play :Eb5
sleep 0.5

Finally, especially if you are delving into algorithmic composition, you can play with a note value defined in a variable:

middle_c = 60

play middle_c
sleep 0.5

Sequences

Sequences of single notes are played using play_pattern or play_pattern_timed. If you are using a specific tempo, you can use play_timed to play a sequence of notes using the current tempo. The notes are written as a comma delimited list:

play_pattern [40, 45, 44, 43]

If you prefer to explicitly specify timing, you can use play_pattern_timed and give individual delays between each pair of notes. Playing these two notes one after another:

play 60
sleep 0.5
play 65
sleep 0.75

is the same as this:

play_pattern_timed [60, 65], [0.5, 0.75]

If the delay between notes is the same we can shorten it to:

play_pattern_timed [60, 65], 0.5

We can also cycle the timing between values in the timing list by providing fewer timing values than note values.

play_pattern_timed [60, 65, 60, 62], [0.5, 0.2]

will alternate between delays of 0.5 and 0.2 seconds for each pair of notes. Using play_pattern makes the code more readable, you can keep related groups of notes together rather than long passages of single play/sleep pairs.

Chords

A chord is a collection of notes played at the same time. Because it is a collection, sonic pi uses the same list notation that the play_pattern function used:

play_chord [ :C3, G3, :C4 ] # power chords !!!
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