audio reactive visuals, routed by you
The filter moves to the beat because you wired the beat to that filter. Any signal kott hears can drive any control.
- beattriggerSEPARATIONrgb-split
- bassrideCELLhalftone
- swellbuild · droprideLENGTHpixel-sort
- not lighting
- No LED strips, no DMX or Art-Net, no lasers, no Arduino or ESP32, no serial or OSC output. For lights you want a DMX or LED controller.
- not a video source
- No NDI, no Syphon, no virtual camera, so kott cannot feed another app. OBS can still capture the window.
- listens to
- A microphone, your system audio, or an audio file you load.
- price
- The spectacle effects, spectrum-bars among them, are paid. Every effect previews free and a free set exports. $59 once, for the web studio and the macOS app.
01/ NOT THIS
if you came here for lights, this is the wrong tool
“Audio reactive” is two searches wearing one phrase, and one of them is about physical lighting. kott has no way to drive any of the above and no bridge that would add one. What it reacts with is an image: a camera, a video file or a still, processed on the GPU and shown on a screen or a projector. If the thing you want to react is physical, no setting turns kott into a lighting controller.
02/ ROUTING
an audio bus, not audio-reactive effects
This is the difference between kott and most of what else comes up for this search, and it is worth reading before the feature list.
a pulsing effect is not a routable bus
Most tools here ship effects with the reaction baked in: the bars follow the volume because whoever wrote the effect decided so, and you get a sensitivity slider. kott analyses the audio once, publishes the results as signals, and lets you decide where each one lands.
any signal onto any parameter
Pick a source (onset, the beat, the downbeat, the build meter, tempo, a frequency band, one of your own EQ bands) and a destination, which is any parameter any effect exposes: threshold, angle, scale, dot size, warp, palette position, contrast, line weight.
each connection has its own gain and smoothing
Gain sets how hard a route pushes, so one onset can shove one parameter and nudge another. Smoothing chooses between a hit that snaps and one that swells, which is why the same wiring reads as a strobe on one parameter and as breathing on the next.
one master over all of it, and LFOs
AUDIO REACTIVITY scales every route at once, for the room where the PA is louder than you planned. Sine, triangle and drift LFOs patch the same way, for parameters that want a slow drift that ignores the track.
03/ SIGNALS
what the audio is actually broken into
A routing matrix is only as good as what it has to route. These are the sources kott publishes, under the names the ROUTES list uses, moving on a demo clock at 120 bpm.
onset
spectral flux
An onset is the moment a new sound starts, which is not the moment the audio gets loud. kott finds it with spectral flux: it compares this moment’s spectrum with the one before and measures how much energy moved upward across the bands. A quiet but sudden hi-hat gives a large flux; a pad swelling to full volume gives almost none. Wired to a parameter, onset moves it on events rather than on level, so it reads as rhythm and not as a VU meter.
beat
phase-locked pulse
A track has more onsets than beats. The beat tracker estimates the underlying pulse and locks to its phase, so it keeps the beat through a bar where the drums drop out and does not fire twice on a flam. Tempo is tracked between 60 and 180 BPM, three ways: autocorrelation on the incoming audio, a fixed BPM you type in, or an external MIDI clock.
bar
the downbeat
The first beat of every four-beat bar, told apart from the other three. A look that changes on every beat is exhausting; one that changes on the downbeat is a phrase. Put a hard change on the downbeat and a small one on the beat, and the visual gains a structure it did not have.
swell
build and drop
A build is a sustained rise in energy, the part of a track climbing toward something, and the drop is the release at the end of it. kott tracks both with one slow meter that ramps up through the build and falls away at the drop, so a parameter can follow the shape of the whole section instead of stepping on each beat. A beat detector alone cannot give you that.
bass · mid · treble
fixed bands
Three fixed bands, always there, nothing to set up. This is the quick route: the kick on one parameter, the vocal range on another, cymbals on a third, and something useful is on screen within a minute.
your own eq bands
two to eight
When three are too blunt, define between two and eight bands, each with its own frequency window and gain. A band gate sets the level a band has to clear before it sends anything, so a band aimed at a snare stays quiet through the bass instead of smearing the whole mix onto your parameter. This is how one element of a track gets a parameter of its own.
04/ DRAWN
effects that draw the sound directly
Routing moves a parameter. A smaller group of effects reads the spectrum and waveform as image data and draws them. These are the ones for when the sound itself should be visible, and they are paid.
spectrum-bars
The vertical FFT bar graph everyone pictures when they say music visualiser. Frequency runs left to right, the source image tints the bars, and the peak caps glow.
oscilloscope
The waveform itself, drawn as a glowing trace with a gaussian bloom. Not the spectrum but the actual shape of the wave, which reads as a signal rather than a chart.
radial-spectrum and freq-rings
The same spectrum wrapped into a circle, or rendered as concentric rings. Both suit a square crop better than a bar graph does.
reactive-warp and signal-wave-plus
The source image warped by the audio, or a waveform with more shaping than the plain trace, rather than a chart drawn on top.
datamosh-real
Compression-artefact destruction driven by the signal rather than by a timer, so the smearing lands with the track.
05/ IN
OUT
a clock, the inputs, and what comes out
the midi clock
24 ppqn
A detected tempo is a guess; a clock is not. kott reads MIDI realtime clock off the port (0xF8 at 24 PPQN, with start, continue and stop) and takes BPM and quarter-note phase from it. When a DAW, a drum machine or a DJ mixer already decides the tempo, the visuals follow it and do not drift over a long track. With no clock on the port, the tracker estimates or holds a typed BPM, which works less precisely.
hardware in a browser
webmidi
A controller works in a browser tab with nothing installed. A nanoKONTROL2 map ships with kott, and any control MIDI-learns onto any parameter, including the routing gains, so how hard the audio drives a look can sit under a fader.
what goes in
sound and picture
A live microphone, your system audio, or an audio file you load, all analysed the same way. The picture is a live camera, a video file or a still: the audio does not generate the image, it moves the effects applied to it. Camera and microphone are processed on your own machine, and nothing uploads.
what comes out
files and screens
REC writes the canvas to an MP4 with a loaded audio file in sync. The microphone and system audio are only listened to, never recorded, so a take driven by either comes out without that sound. Stills come out as PNG, or as vector paths for print and plotters, and projector mode mirrors the output to a second window for the room.
06/ LIMITS
what it will not do
no physical lighting
No LED strips, no DMX or Art-Net, no lasers, no Arduino or ESP32. The output is a canvas, and that is the end of it.
no video feed to other apps
No NDI, no Syphon and no virtual camera, so kott cannot appear as a source in Resolume, Zoom or anything else. OBS can still capture its window like any other window, which is how it gets onto a stream.
not a mixer or a media server
No clip grid, no cue list, no timeline. You play what is on screen; you do not fire clips from a rundown.
a narrow visual language
Dither, halftone, print, ASCII, engraving, glitch, CRT, on purpose. No 3D, no generative geometry, no particle scenes. For reactive particles in a 3D world, you want a different kind of tool.
the spectacle effects are paid
spectrum-bars among them. Every effect previews free with no account, and a free set exports without paying, but exporting these needs the one-time licence.
offline means macOS
The native build that runs offline is macOS only. On Windows and Linux, kott is a browser tab with WebGL2.
07/ FAQ
questions
what is audio reactive visuals?
Audio reactive visuals are images that change in response to sound analysed in real time, rather than to a fixed animation timeline. The audio is broken into measurable signals (the onset of a new sound, the underlying beat, the energy in a frequency range) and those signals drive properties of the image. The distinction worth knowing is between an effect with a reaction built in, which gives you one behaviour and a sensitivity slider, and a routable audio bus, which publishes the signals and lets you decide which parameter each one moves. kott is the second kind: any analysed signal can be routed onto any effect parameter, with its own gain and smoothing.
how do I make visuals react to music?
Give the tool the audio, pick a signal from it, and connect that signal to a parameter you want to move. In kott that means choosing the microphone, system audio or an audio file as the input, then routing a source (onset, the beat, the downbeat, the build meter, bass, mid, treble, or an EQ band you defined) onto a parameter of the effect that is running. Each connection has its own gain, so you set how far the parameter travels, and its own smoothing, so you set whether it snaps or swells. Start with one: a bass band onto contrast is legible immediately and tells you whether the gain is right before you add anything else.
can I use my own music?
Yes. Load an audio file and kott analyses it exactly as it analyses a live input, and REC writes the canvas to an MP4 with that file’s audio in sync, so the reaction you watched is the reaction in the file. You can also play the track anywhere on the machine and use system audio as the source; that drives the visuals but is not recorded. Nothing uploads; the audio is processed on your own device.
does it work with a microphone?
Yes. A live microphone is one of the three inputs, alongside system audio and a file, and the full analysis runs on it: onset, beat, downbeat, the build meter, tempo between 60 and 180 BPM, the fixed bass, mid and treble bands, and up to eight EQ bands you define. The microphone is processed on your device and nothing is uploaded or recorded. It is the input to use for a live band, a room, or a DJ you are not patched into.
can it control LED lights?
No. kott produces pixels on a screen and nothing else. It does not drive LED strips, it does not speak DMX or Art-Net, it has no serial, OSC or WebSocket output, and it does not talk to an Arduino, an ESP32 or a laser projector. If you are building an audio-reactive light, you want a DMX controller or an LED controller, not this. kott is worth your time only if the thing you want to react is an image.
08/ NEXT
where to go from here
This page is about the mechanism, how a signal reaches a parameter. The pages below answer different questions.
- a visualiser video for a trackmusic visualizer →The outcome rather than the wiring: load a track, choose a look, get an MP4 with the audio in sync.
- you have footage and a songaudio reactive video →Your own clip with the effects moving to the track, recorded to MP4 with the song in it.
- live on a streamstream visualizer →The output in a window that OBS captures, moving to your mic or your music while you broadcast.
- you are choosing between toolsvj software →kott next to Resolume, VDMX, TouchDesigner, Synesthesia, Magic, Mosh-Pro and Hydra, with real prices and when to buy the other one.
- your source is a live camerawebcam dither →The camera path in detail, where the frames go, and why dithering a moving image is harder than a still.
09/ OUT
wire one signal and look at it
The studio opens on spectrum-bars with the audio input ready. Route a bass band onto one parameter, play something, and within a minute you will know whether this is the shape of tool you wanted.
open the studio with audio in →
- try
- Free preview in the browser, no account, no install.
- licence
- $59, once. Web studio and macOS app, no subscription.
- your audio
- Analysed on your own machine. Nothing uploads.