AI AutoMixer

Architecture

The AutoMixer is a Utility AI (not a state machine). Multiple intents can fire simultaneously across different domains. The engine ticks at 50 ms (20 Hz) — at 170 BPM that's ~5.7 ticks per beat.

AI Modes

Mode	Behavior
OFF	Engine disabled
CRUISE	Runs continuously. Any user interaction kills the AI permanently
ASSIST	Pauses when user interacts. Resumes after configurable inactivity delay

Tick Loop

Each tick:

1. Check mode (OFF = skip, ASSIST = check pause/resume)
2. Clear ghost fields from previous tick
3. Compute Blackboard (all deck/master state)
4. Score all 20 intents via intent.evaluate(blackboard)
5. Sort by score descending
6. Arbitrate: fire each intent unless its domain is locked by a higher-scoring exclusive intent
7. Execute winners, marking affected controls as "ghost fields"

Ghost Fields

When the AI manipulates a control, it's marked as a ghost field (e.g., "A.eq.low", "crossfader"). UI knobs with ghost fields glow purple, showing the user which controls the AI is touching. Ghost fields are stored in a global Set outside Zustand to avoid 50 ms re-render storms.

Blackboard

Variables computed once per tick from the Zustand store and audio engine:

Deck Roles

Variable	Description
masterDeck	Louder deck or only playing deck (default A)
incomingDeck	The other deck

Timing

Variable	Description
masterCurrentBeat	Current beat position
masterBeatInPhrase	Position within 16-beat phrase (0–15.99)
masterOnDownbeat	Beat mod 4 < 0.5
beatsToOutroMaster	Beats remaining to track end
deadAirImminent	< 8 beats remaining

Spectral

Variable	Description
bassClash	Both decks' low EQ > -10 dB
midClash	Both decks' mid EQ > -6 dB
incomingBassKilled	Incoming EQ low < -15 dB
masterHasFilter	abs(colorFx) > 0.3

Harmonic

Variable	Description
masterKey / incomingKey	Camelot notation
isHarmonicMatch	Camelot ±1 (compatible keys)

Phase

Variable	Description
isPhaseAligned	Within ±50 ms
phaseDeltaMs	Signed, positive = incoming behind

The Blackboard has an optional Wasm fast path — if the Rust module is loaded, 18 floats are packed into a Float64Array and computed in Wasm.

All 20 Intents

Safety Domain

Intent	Score	Trigger	Action
Dead Air Prevention	1.0	< 8 beats to end, no loop	Engages 4-beat auto-loop
Phase Drift Correction	0.6–0.9	Both playing, > 10 ms drift	Proportional pitch nudge (0.5–2%) then restore
Red Line Limiter	0.92	Both volumes > 0.8, EQ boosted	Reduces master volume to 0.7
EQ Amnesia Recovery	0.7–0.85	Bass killed > 1.6s while solo	Gradually restores bass +2 dB/tick

Spectral Domain

Intent	Score	Trigger	Action
Drop Swap	0.9	Both playing, bass killed, phrase boundary	Swap bass: master → -26 dB, incoming → 0 dB
Sub Rumble Control	0.7	Bass clash detected	Incoming low → -15 dB
Hi-Hat Layering	0.4	Incoming bass killed, highs < -2 dB	Incoming high → 0 dB
Vocal Space Carving	0.5	Mid clash detected	Incoming mid → -8 dB
Isolator Sweep	0.35	Solo, EQ flat, near phrase boundary	Sweeps all EQ to -20 dB, snaps back at boundary

Dynamics Domain

Intent	Score	Trigger	Action
Filter Washout	0.1–0.8	Bass killed, within 16 beats of phrase	Ramps master colorFx to 0.7 (HPF)
LPF Mud Dive	0.05–0.5	Bass killed, no filter	Ramps master colorFx to -0.5 (LPF underwater)
Pre-Drop Silence	0.95	0.3–1.0 beats to phrase boundary	Sets BOTH volumes to 0
Filter Wobble	0.55	1–8 beats to phrase, no filter	Oscillates colorFx ±0.2 every half-beat
Build-Up Tension	0.65	4–16 beats before incoming drop, no filter active	Progressive HPF sweep (colorFx 0.15→0.85) proportional to countdown
Ghost Note Echo	0.48	Master vol ≤ 0.45 and incoming > 0.6 (fade-in moment)	Bass kill proportional to fade depth, hi-mid boost +4 dB, 1/4-note colorFx tremolo

Rhythm Domain

Intent	Score	Trigger	Action
Loop Roll Buildup	0.75	Within 16 beats, incoming ready	Cascade: loop(4) → loop(2) → loop(1) → loop(0.5) → exit
Teaser Stab	0.45	Incoming silent, bass killed, every 4th downbeat	Flashes incoming volume to 1.0 for quarter-beat

Structure Domain

Intent	Score	Trigger	Action
Outro Riding	0.3	8–64 beats to end, no clash	No-op: claims domain to prevent premature transitions
Double Drop Align	0.2–0.6	Both have drops, > 32 beats lead	Micro playback rate nudge (±0.5%) to converge drops
Key Clash Defense	0.8	Keys not harmonically compatible	Kills incoming mids to -20 dB; ramps master HPF

Intent Domains & Exclusivity

Intents are grouped into 5 domains: safety, spectral, dynamics, rhythm, structure. Within each domain, exclusive intents lock the domain — lower-scoring intents in the same domain are blocked. Non-exclusive intents can stack freely.

MIDI

Device Detection

Uses navigator.requestMIDIAccess({ sysex: false }). Hot-plug/unplug handled via onstatechange.

CC Mapping (Learn Mode)

1. UI component calls window.__MIXIMIDILEARN__() to enter learn mode
2. Next incoming CC or Note message is captured
3. Mapping stored: { portId, type: 'cc'|'note', channel, control, action }

Mappable Actions

CC Actions (Continuous)

Action	Parameters	Range
CROSSFADER	—	0–1
MASTER_VOL	—	0–1
HEADPHONE_MIX	—	0–1
HEADPHONE_LEVEL	—	0–1
DECK_GAIN	deck A/B	-12 to +12 dB
DECK_VOL	deck A/B	0–1
DECK_EQ_HIGH	deck A/B	Scaled by EQ range
DECK_EQ_MID	deck A/B	Scaled by EQ range
DECK_EQ_LOW	deck A/B	Scaled by EQ range
DECK_FILTER	deck A/B	-1 to +1 (bipolar)
DECK_PITCH	deck A/B	±8% (hardcoded)

Note Actions (Toggle)

Action	Parameters	Description
DECK_PLAY	deck A/B	Toggle play/pause
DECK_SYNC	deck A/B	Toggle sync
DECK_CUE	deck A/B	Toggle CUE
GROOVEBOX_PAD	deck, voice	Trigger drum pad

Known Issue

DECK_PITCH range is hardcoded to ±8%. A TODO comment mentions adding configurable pitch range, but it's not implemented.

MIDI Clock

Output

• 24 ppqn (standard MIDI clock)
• Look-ahead scheduler: checks every 10 ms, schedules 25 ms ahead with hardware timestamps
• Sends to ALL available MIDI outputs

Input

• Receives clock ticks, averages last 24 ticks to compute external BPM
• Exposes externalBpm and hasExternalClock

Skins

Built-in Skins (3)

Skin	Description
midnight	Dark blue theme (default)
freetekno	Warm rust/earth tones
carbon	Neutral gray

Custom Skins (17 bundled)

Acid, Aqua, Arcade Invaders, Blackfluo, Bloodmoon, Casino, Dune, E-Ink, Gold, Hologram, Industrial, Matrix, Nordic, Synthwave, Vaporwave, White, and Freetekno (duplicate of built-in — will be resolved when custom skins migrate to external repository).

Custom Skin Format

A folder containing two files:

skin.json

{
  "id": "my-skin",
  "name": "My Custom Skin",
  "dotColor": "#ff0088"
}

skin.css

CSS file with custom property overrides. Injected as a <style> element. Basic security: rejected if it contains <script, javascript:, or expression(.

Loading Custom Skins

Click the folder icon in the topbar skin selector to open a directory picker. The skin is loaded, validated, and stored in localStorage for persistence.

Groovebox

Overview

4-voice drum machine with 16-step sequencer, per-voice synthesis, and MIDI input.

Voices

All voices are pure WebAudio synthesis — no sample files required.

Voice	Method	Duration	Details
Kick	Sine pitch-sweep	250 ms	150 → 50 Hz exponential, exp(-12t), gain 0.9
Snare	Noise + sine	180 ms	White noise exp(-20t) at 0.5 + 200 Hz sine exp(-30t) at 0.4
Hat	HP filtered noise	80 ms	First-order difference filter, exp(-50t), gain 0.35
Perc	Two detuned sines	100 ms	800 Hz + 1127 Hz (metallic), exp(-35t)

Custom samples can be loaded via drag-and-drop onto sequencer rows.

Sequencer

16 steps per pattern. Each step is a boolean (on/off) per voice. Per-voice volume (0–1, default 0.8). Swing 0–0.5 applied to odd steps.

Scheduling: 25 ms timer, 50 ms look-ahead, 16th note resolution.

Per-Voice Mixer

Control	Range	Description
Pan	-1 to +1	Stereo position
Mute	on/off	Silences voice
Solo	on/off	Solos voice (mutes others)
Volume	0–1	Per-voice gain

Bus Routing

Groovebox voices → per-voice gain/pan/mute → Bus output → DeckChannel.input
→ EQ → ColorFX → Fader → Crossfader → Master

The groovebox routes through the standard deck channel, so deck EQ, effects, and crossfader all apply.

MIDI Input

Receives GROOVEBOX_PAD events from the MIDI manager. Velocity (0–1) is applied as gain. Polyphonic — multiple voices can trigger simultaneously.

Stub Feature

The 8 FX pad buttons in the Groovebox UI (LPF, HPF, DLY, RVB, GATE, DIST, FLG, STT) are purely visual toggles. No actual audio FX processing is connected to the groovebox audio graph. Clicking them changes React state only.