What if it ran on a Pi?

Eight days in, WaveLoop was a plugin, a Mac app in progress and an iPhone app in review. Then one line changed what kind of thing it was.

What if it ran on a Pi?

Elijah · Mar 2

A Raspberry Pi 4, a HyperPixel 4.0 screen, a UA Volt 276 audio interface and an Arturia MiniLab 3. No desktop. The tape was rewritten in C against raw ALSA at 48 kHz and drawn with SDL2 straight onto the display: no X11, no Wayland, just pixels.

It took three failed tries at rotating the picture before rendering to a texture got the portrait screen right side up. The first login failed for three minutes because the account wasn't called pi. By the end of the day it had a full transport (play, record, rewind, reverse, loop in and out), pads lit in colour, and a take saved to disk every time you hit stop. It compiled with zero warnings on ARM.

5:21 am.

Day two brought effects: a gate, a compressor, a delay, and an encoder that scrubs the tape like a turntable, with inertia. Then this arrived.

OMG THIS DELAY IS SO FUCKING COOL. I'm gonna play with this and brainstorm some more ideas... this is the coolest shit ever... good night. Make best guesses, worst case, we roll back in source control <3

Elijah · Mar 3, 5:21 am

He stayed up. Eighteen minutes later:

I always forget I can load another terminal... I tried killing it: ^C^C^C^C^C

Elijah · Mar 3, 5:39 am

By that night there were fourteen effects, two independent effect loops, and tape loss: every overdub wears the recording a little. The cheap degradation from the week before was now running on a board the size of a credit card, and the whole thing used 9.8% of its CPU.

Play the damage.

On March 4 the lower two octaves of the keyboard became twenty-four momentary effects (wobble, erode, crackle, stutter, tape stop) that burn into the tape for as long as you hold the key. Hold three keys, get three at once. No undo, as usual.

Under it, three threads (audio, MIDI, display) share their state without a lock, so the audio never waits for the screen.

That box is waveOS now: a free card image for a Pi 4 or 5. Plug in an interface and a keyboard and it boots straight into the tape.