Episode: 1775
Title: HPR1775: Sonic Pi
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1775/hpr1775.mp3
Transcribed: 2025-10-18 09:07:15

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This is HPR episode 1775 entitled Sonic Pie.
It is hosted by Steam Vehicle and is about 11 minutes long.
The summer is a short-remew on Sonic Pie and programming the HPR theme.
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Hi, I'm Steve Vehicle and this is my HPR episode about Sonic Pie.
I recently bought a Raspberry Pi 2 to play with.
I installed the Raspberry OS onto an SD card.
I had a bit of a challenge getting online as the BT router doesn't want to play with
with the Wi-Fi on the Raspberry Pi.
It also fails to connect with a friend's MacBook Pro, so I'm sure it's the router that's
a fault.
And the Ethernet via the mains gadget didn't work either.
Unfortunately, there's no HDMI monitor to hand under the stairs where the Ethernet
is available, so I was limited to offline use for my Raspberry Pi.
Fortunately, you get the pre-packaged educational programming software, Scratch and Sonic Pie.
So there are toys to play with without going online.
I'd seen Scratch before, but I'd never come across Sonic Pie.
Sonic Pie is a music program, but it's different to any that I've seen before.
It's a procedural programming language for making a manipulating music.
Despite its primary purpose, being a simple way to introduce programming concepts to children,
the underlying capabilities of the Sonic Pie language are really sophisticated.
It has constructs that allow for looping, manipulation of samples, the ability to build
sounds from primitive oscillators with attack, decay, sustain, release, envelope shaping,
and complementary to that, it also allows conventional musical constructs such as sequencing
of individual notes, chords, scales and arpeggios.
When you list its capabilities, you might expect learning to use the Sonic Pie would be
quite a daunting task, but it's not.
Sonic Pie has been designed to educate children about programming, and it comes with a simple
tutorial and some inspiring examples, along with relatively comprehensive documentation
for the language, samples and oscillators.
On a single screen, there are eight tabbed workspaces where music scripts can be written, a runtime
viewer showing the actions being taken by your running program or programs, and the information
pain, where tutorials or documentation can be viewed whilst programming.
Some Aaron, who wrote Sonic Pie, is one of a community of live performers of music programming.
Sonic Pie allows for live looping, where the programs changed on the fly and re-envoked
with new code to move the performance on.
There are mechanisms to create threads that run separately, but can be synchronised with
each other.
There's the ability to use random numbers to add variability into your program.
A nice touch here is that the random number generator seed is always the same, so a program
will perform repeatedly in a consistent manner.
Some has managed to orchestrate, no pun intended, a swath of complex libraries, and optimise
the coding of Sonic Pie in such a way that it's possible to produce a sophisticated multi-layered
soundscape with the relatively meager resources of the Raspberry Pi and a few lines of code.
I've never learned to play, I've never played a musical instrument, but after a couple
of hours with Sonic Pie, a sheet of music, and a giff image I found listing the names
of the notes in a treble clef, I have a program to play the tune to Flanders and Swans
Hippopotamus song, a task I originally achieved back in the early 1980s on an Atari 400.
This is not a very sophisticated rendition, and sort of misses the point of the looping
capabilities of Sonic Pie, but it made me smile.
So I thought I might take things a step further and try something a little bit more ambitious,
the HPR theme.
Not being a musician, I can't tell what note is being played by listing alone, all the
timing for that matter, and there was no sheet music to hand.
I managed to hack around this by playing the accordion version of the Outtrace theme
from the HPR website on my laptop with a guitar tuner program on my Android phone displaying
the pitch.
To get the basic two note timings down, I used this setup, and listened to it many times
at half speed, quarter speed, and also listened to the main theme version in VLC as well.
Finally, I used Audacity to listen to portions of the tune repeatedly by selecting sections
and hitting the space bar to replay.
After a few hours of this, I'd hacked out a version of the tune into a program.
This was still just sequential notes and sounded very flat and mechanical.
The default sound is a beep, I changed the voice to a sawtooth waveform which sounds
more like a brass instrument.
For the last few bars, I changed to an alternate voice to give a richer sound, then changed
the final notes to chords to build up the sound.
On the main theme, there's a light, percussive, urgent background beat, so in another workspace,
I put together a loop to do this.
And again, it took me a non-musician some time to get anything that sounded ok.
Once I had percussive loop, I added it to the main program in the first workspace, setting
up the loop in a separate thread so it would play simultaneously with the tune.
There are also a couple of drum beats to introduce the main theme, so again in a separate
workspace, I played around with sample drum sounds and timing to get something I was happy
with, and then inserted it into the main program.
For any Raspberry Pi owners or Apple Mac owners, that being the only other platform the apps
currently packaged for, I've added my two programs to the show notes.
I'm not sure that we're allowed to perform the hippopotamus song on a Creative Commons
podcast, so I'll not play it here.
Instead, to show what's possible when somebody talented programs with Sonic Pi, I'll play
back a piece from the Sonic Pi demos.
Yeah, yeah, yeah, yeah, yeah, yeah, yeah.
That was Shuffleit by Sam Aaron, that was just 41 lines of code, and I think for such a
small amount of code, that's an impressive soundscape.
The HPR Outro is Creative Commons compatible, so I'm going to end this episode with a result
of my less talented music endeavors, again, I'd refer you to the show notes for this listing
and I'd ask you to take it and hack on it, make it into something better, and yes,
make an episode about it.
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