About

Every voice keeps its own time.

Polyrhythm Engine plays polyrhythms you can watch. Each voice goes round at its own speed and sounds a note every time it comes round, over a slow chord progression. The speeds never quite match, so the voices drift apart and fall back into step, and every piece has a scene that moves with the music.

Every shot in the film is the engine itself, and the music is its built-in synth playing exactly the notes you see.

How it works

Every voice has its own speed

A voice's speed is how many notes it plays per beat, written as a fraction: 3/2 plays three notes every two beats. Low voices tend to be slow and high ones quick, so the pattern never sits still.

The picture is the score

Each preset is a piece: the music plus a scene that draws it. Every note lands on a moment you can see — a jellyfish squeezes, a crest breaks, a solid clicks home — so you can watch the next note coming.

Every piece comes back round

The built-in pieces are made to loop: the voices line up again after a set number of bars, and the Loop tab shows exactly when. Play one loop from the top and record it, and it loops seamlessly in your DAW.

Made for playing along

A built-in ambient synth

Bells, soft keys, kalimba, harp and more, over a chord pad, in a long reverb with a stereo echo. Nothing to install: it plays in the browser.

MIDI out to your own instruments

Send every note to your DAW or VST. Notes are timed ahead, so they stay tight even when the picture stutters. The chord pad and the bass can each have a channel of their own, and there's a sustain pedal.

Export one loop as MIDI

A .mid file of exactly one loop: every voice, the chord names as markers, and the pad and bass if they're switched on.

Make your own

Change the speeds, the scale, the chords, the tempo and the unison drift, put any scene to any music, and save it as a preset of your own.

Autopilot and playlists

Let it tour the pieces on its own, or line up your own playlist. Each piece hands over to the next at the end of its loop.

Looks to match

Every scene has its own colours and light. Turn up the glow, thin the lines, or hide every control and just let it play.

Some of the pieces

More than seventy of them, each a scene with its own music.

Midnight SeaTwenty rows of swell under the moon, each crest breaking as it sounds
Deep BloomTwelve jellyfish pulsing up through the deep, the big ones low and slow, the small ones quick
Night MazeA slow walk through a firelit brick maze, eight wisps leading the way
Platonic DriftFive solids nested inside each other, two copies of each clicking round and sliding into moiré
Hyper TunnelHexagon rings drifting toward you down an endless tunnel, a spiral threaded through them
Groovy LampOne lava lamp in a dark room, five slow blobs of wax rising, merging and sinking
Brass ArmillaryNine tilted rings nested like an old armillary sphere, turning slowly in the firelight
Violet HelixA turning double helix, beads bouncing strand to strand on sixteen rungs
Pollen BloomA slowly turning dandelion head of forty-eight spikes, ripples of notes running over it
PulsarForty ridges in black and white — each peak surges as it sounds
Lantern FestivalLanterns on a dusk lake, each letting a sky lantern go on its note
GargantuaA black hole wrapped in fire, ten clumps of light circling the edge

At the keyboard

Space pause
M the scene browser
N next piece
R back to the start
L the loop
H hide the controls
/ search
Esc back

Press play.

Open the engine

Best on a computer, with headphones or good speakers. MIDI out needs a browser with Web MIDI, such as Chrome or Edge.