1What it is

A fractal is drawn sixty times a second, and the sound decides how it folds, turns, pulses and colours. Nothing is pre-rendered and nothing is on a timeline: the picture is the sound, arriving as it arrives.

It is an instrument rather than a filter. The controls are there to be played — by hand, by preset, by MIDI, or by the track itself.

Recordings come out as MP4 with the audio already in them, at up to 2560 × 1440.

2Getting started

One file, no installation

Everything is inside the one HTML file: the code, the shaders, the artwork and the demo song. It runs offline, from a local disk, with no server. Nothing is uploaded anywhere, because there is nowhere for it to go.

It needs WebGL2 — current Chrome or Edge on a machine from the last several years. A message says so plainly if the browser cannot run it.

The Terms

The first thing shown is the Terms of Use, with I AGREE & CONTINUE at the foot. The short version: what is made with the software belongs to whoever made it, the supplied song may be used commercially with a credit, and anything brought into the app is the responsibility of whoever brought it.

TERMS.txt beside the app is the same text, for keeping.

Giving it sound

Three sources, chosen at the top of the panel:

The whole window is a drop zone. Drop an audio file anywhere and it loads as the track; drop an image anywhere and it becomes the picture. The app sorts by file type. CHOOSE FILE and CHOOSE IMAGE do the same thing by dialog, for phones and for anyone who would rather click.

The song that comes with it

The plaque reading THE SOUND UNBOUND is a button. Pressing it plays the song that ships inside the file — The Sound Unbound by Per Sonum — so there is something to react to before any track is loaded.

It is included to be used, not only demonstrated. See Terms and credits.

3The three versions

The same app, packaged three ways. They behave identically; the difference is what travels with them.

4The two tabs

EASY MODE carries everything needed to get a good picture and record it.

ADVANCED carries the rest: the motion sliders, the six-part analysis, the listening controls, quality, camera, timing, MIDI.

On a wide window ADVANCED spreads into a second rail beside the first. On a narrow one it stacks. Knobs and sliders are the same controls in both places.

5EASY MODE

Music

The source buttons, CHOOSE FILE and CHOOSE IMAGE, the demo plaque, and — once a track is playing — its name and progress.

Shape

Your picture

Colours

Presets

Ten slots. Clicking an empty slot saves the current look into it straight away; clicking a filled one loads it. SAVE writes to the highlighted slot, CLEAR empties it, and the number keys 1–9, 0 load them.

RECONNECT DEFAULTS puts every look and motion setting back to the way the app opens, and lets the settings that follow the music do so again. Several controls follow the world until they are moved by hand, and then stop; this is the way back. The track, the picture and the saved presets are kept — it is the look and motion that returns, not the session. It is itself undoable.

Chance & safety

Record

Resolution, quality and the record button. See Recording, in detail.

6ADVANCED

Motion

Flight, Fold, React, Pulse, Spin — the five that decide how the world moves and how hard the music moves it. Fold is the one that changes the geometry most; React is the overall coupling between sound and picture.

Parts

WHOLE MIX treats the track as one signal. ZONES splits it: each of six parts is assigned to a region of the picture, with its own effect and amount.

Also Wash and Rings — two overlay motions that read the mix.

Musical reactivity

Six parts, by register and by kind:

The split works by finding what is brief and broad (a hit) against what is held (a tone), in the spectrum over time.

Listening

Quality

Detail, Steps, Scale. Detail and Steps set how much of the fractal is resolved; Scale sets the ceiling for the automatic resolution governor.

View

Zoom, and Endless — keep falling inward without arriving.

Camera

Audio

Image

Recording

Frame rate — 60 fps, or 30 for smaller files. Render — record at full size, or at 75% / 50% and scale up, which holds the frame rate on slower machines.

MIDI

CONNECT, then LEARN and move a control and then a knob to bind them. CLEAR ALL forgets the lot. Bindings persist.

About

The app's name and version, and the buttons for the full ABOUT text and the TERMS OF USE.

7The shapes

Twenty-one, in the order they appear:

TUNNELS · CHAMBERS · ORBS · LATTICE · SHELLS · STRATA · EYE · LEAF · CYLINDER · CONE · TORUS · CAPSULE · PYRAMID · OCTAHEDRON · ICOSAHEDRON · PRISM · STAR · CROSS · FRAME · LINK

and CUSTOM IMAGE, which folds the supplied picture itself and sits last in the menu because it behaves differently from the rest: it is always flat — the 3D box is disabled while it is chosen — and its shape is whatever the picture's outline turns out to be.

It is also the shape the app opens on, which is why the 3D box seems to do nothing at first: choose any other shape and it wakes.

S steps through them.

8The picture you bring

The picture is used twice over, and it is worth knowing the difference.

As material. It is sampled for colour and texture wherever the fold shows it.

As a shape. Its outline is read into a distance field, and the fractal folds around that. The outline is found in one of three ways, whichever fits:

1. Its transparency — if the image has a real alpha channel. This is the cleanest, because the silhouette is exact rather than guessed.
2. Its background colour — the four corners are averaged, and everything far enough from that colour becomes the shape.
3. Its darker and lighter halves — the fallback when neither of the above applies.

A bold shape on a flat background reads best. A busy photograph will read as a rectangle, which is a perfectly good anchor but a dull one. PNG, JPEG, WebP, GIF, BMP and AVIF are read; SVG is not — export it as a PNG first.

The app opens with its own plaque as the picture — a transparent WebP, so the outline comes from its alpha.

9Directed by the track

With a loaded track, Directed by the track listens beyond the immediate beat. It looks for rhythm, energy, sections, builds and drops, and uses that musical shape to steer the visual performance — while leaving the underlying look as set.

It does not overrule chosen colours or shapes. Presets are recalled, never imposed.

The note beneath it reports what the app has made of the track and what it is doing about it right now. If the tempo reads wrong, tapping the beat overrides all of it.

10How it listens

For the curious. The sound is analysed about sixty times a second into:

• Four bands — bass, low mid, mid, high — driving the overall coupling and the colours.
• Six parts — as above, split by brief-and-broad against held.
• Beats — an onset detector; the tempo shown is the median interval between onsets, folded into 70–180 bpm.
• Chroma — pitch content as well as energy, so a bowed slide or a held solo registers even when nothing is getting louder. Flux alone is deaf to that.
• A local baseline — loudness is judged against the passage it sits in rather than against the whole track, so a quiet section is not simply quiet.
• Envelopes — nothing reaches the picture raw. Every signal passes through a fast rise and a slower fall, so the picture follows phrases rather than flickering with frames.

In FILE mode all of this is done once, in advance, for the whole track. In LIVE and THIS COMPUTER modes it is done as the sound arrives, a few frames behind.

11Recording, in detail

• Output is an MP4 with H.264 video and AAC audio — the file Windows, phones, VLC, editors and upload sites all accept.
• In FILE mode, pressing ● also starts the track from wherever it is cued, so the first frame already has music under it. The take ends itself when the track ends.
• In LIVE and THIS COMPUTER, ● records what is heard and what is shown, until stopped.
• Keep the window on screen while it records. Browsers stop drawing hidden windows, so a take pauses while the window is hidden and resumes on return — no frozen stretches, but those seconds are not captured either.
• The frame rate is protected. Capture goes through a scaling stage, so the render can be resized mid-take while the file keeps its chosen size. The governor keeps working during a take, downward only.
• Picture and sound are aligned to the same clock. The video track's declared duration is matched to the audio's, so an action taken on a beat lands on that beat in the file, at the end of a long take as well as the start. Nothing is re-encoded to achieve it. A diagnostic speaks only if the two tracks disagree by more than 0.25%, so it is silent on a healthy take.
• Takes are written to disk as they record rather than held in memory, so length is limited by disk rather than RAM.
• The frame size is fixed for the length of a take; the dropdowns are disabled until it stops.
• The file-size estimate is calibrated per machine — every take is measured and the next request adjusted. That calibration is the one thing remembered between sessions.
• A small red pill at the top right shows length, size, rate and frame size while recording.

Filenames carry the track, the tool, the frame size and the moment:

The Sound Unbound - Per Sonum 1920x1080 26Aug2026 0144.mp4
Live Session - Per Sonum 1920x1080 26Aug2026 0144.mp4

The date is written out because 08/09 is two different days depending where you live, and the time is 24-hour with no separator because a colon is illegal in a filename and a dot reads as the extension. There is exactly one dot in the name. Tags do not stack when a recording is re-recorded, names cap at 120 characters, and they sort in the order they were made. Stills follow the same pattern with .png.

12The dock

Along the bottom: play / pause, restart the track, record, and save a still.

13Keys

The panel also hides itself after four seconds of stillness — though never while recording — and comes back on any movement of the mouse. On a touch screen, a tap on the picture toggles it.

14On a phone

It runs. The panel takes the screen, and the file and picture choosers open the phone's own pickers — drag-and-drop is not available on a phone, so the buttons are the route in.

Recording saves through the phone's Downloads folder.

15Performance

Drawing a fractal is heavy work for the graphics card, and the cost depends on resolution, Detail, Steps and the shape. Rather than stutter, the app lowers its drawing resolution on its own when a scene is too heavy, and raises it back slowly when there is room. The current figure shows in the stats line as a percentage next to the frame rate. Scale sets the ceiling it works under.

Roughly, lightest to heaviest: any 2D fold (Custom Image, or a shape with 3D unticked), then the solid shapes. Detail and Steps at maximum roughly double the cost of the 3D shapes against the middle of their ranges.

16Tips and recipes

• A club wall — LIVE · MIC, START LISTENING, H to hide the panel, F for fullscreen. It follows a whole set regardless of whose music is playing.
• Anything playing on the computer — THIS COMPUTER, START LISTENING, choose a screen and tick Also share system audio, then play. The recording takes that sound too.
• A video of a track — FILE · RENDER, drop the track, choose 1920 × 1080 and STANDARD, press ●, and leave the window on screen until the toast says it has saved.
• A branded visual in thirty seconds — CUSTOM IMAGE, drop a transparent PNG of a logo, tick Anchor image, set Anchor size, pick two colours.
• Your own colours from a photo — drop the photo, untick Paint the picture, choose any shape with 3D ticked and Image at 1.
• Calmer — lower Flight and React, raise Smoothing, Pulse to 0.
• Busier — ZONES on, Pulse up, Wash up, Mirrors lower.
• Sharper — lower Detail and Steps a little; it costs far less than it looks.

17If something's wrong

• No microphone. The browser has to be allowed to use it — look for the microphone icon in the address bar. If the browser refuses because the file was opened directly, serving the folder over http://localhost fixes it.
• THIS COMPUTER hears nothing. The audio box in the share dialog was not ticked — it is easy to miss. Stop, start again, choose a screen, and tick Also share system audio. If the dialog has no such box, the browser cannot do it (Firefox, Safari, phones): use Chrome or Edge on a computer.
• A file won't load. MP3, WAV, FLAC, M4A and OGG work. DRM-protected files and some unusual containers don't; convert them first.
• The picture vanished and the app reloaded. The graphics driver reset. The app reloads itself with the settings it had; a recording in progress at that moment is lost.
• Black screen at start. The app needs WebGL2. A message says so if that is the problem.
• The picture looks soft. The app is lowering resolution to hold the frame rate. Lower Detail and Steps, or choose a lighter shape.
• The anchor picture blurs with distance. It is sampled at a level chosen from how far away it is. A larger Anchor size brings it closer and keeps it sharper.
• Beats are detected everywhere / nowhere. Sensitivity — down for the first, up for the second.
• The tempo is wrong. Tap it. Four taps on T override the detection entirely.
• The picture thrashes with no music. Lower Flight; and in LIVE, if the room is noisy, lower Sensitivity.
• Paint the picture does nothing. It engages only for pictures that are genuinely close to two colours. A marbled or photographic image is left alone on purpose.

18What's in the files it makes

Every MP4 and PNG is yours — no watermark, no title card, nothing in the frames. The MP4 carries ordinary "made with" metadata naming the tool, and the link once, in the comment field that editors actually show. There are no artist, album or copyright fields: the video is its maker's work.

19Terms and credits

The full Terms of Use are shown when the app opens, and repeated in TERMS.txt.

What matters most:

• What is made with it belongs to whoever made it.
• The included song may be used, including commercially, with a credit — Song by Per Sonum for the recording, or Written by Kagani Ko for the lyrics used separately. Only the credit that applies is required, and it can live in a description or in credits rather than in the picture.
• Nobody may lock the included material away from anyone else — no Content ID registration or similar of the supplied material.
• Material brought into the app is the responsibility of whoever brings it. The ability to load a file is not permission to use it.