Close out the twenty: what the gates taught
Three lessons worth more than the scenes: a slow axis has to move a large low-frequency area or the camera's own drift beats it, whole-frame luminance on the kick is the strobe the flash gate exists for and it arrives by accident, and a style trait expressed only as grain measures as no style at all. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Dejvino
@@ -35,41 +35,43 @@ import { synthesizeSong } from './synth.js';
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*/
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export const SONGS = [
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// --- slow, quiet, spacious -------------------------------------------
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{ name: 'drone', bpm: 62, arrangement: 'ambient', brightness: 0.10, noise: 0.05, dynamics: 0.90,
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covers: 'slowest · darkest · beatless · most dynamic' },
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{ name: 'air', bpm: 76, arrangement: 'ambient', brightness: 0.85, noise: 0.35, dynamics: 0.85,
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{ name: 'drone', bpm: 62, arrangement: 'ambient', brightness: 0.05, noise: 0.02, dynamics: 0.95,
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covers: 'beatless · darkest · most dynamic' },
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{ name: 'air', bpm: 76, arrangement: 'ambient', brightness: 0.90, noise: 0.25, noiseColour: 0.15, dynamics: 0.85,
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covers: 'beatless but bright — brightness without a beat' },
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{ name: 'elegy', bpm: 84, arrangement: 'ballad', brightness: 0.20, noise: 0.10, dynamics: 0.80,
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covers: 'slow with one build and one payoff' },
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{ name: 'hymn', bpm: 92, arrangement: 'ballad', brightness: 0.75, noise: 0.20, dynamics: 0.70,
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{ name: 'ember', bpm: 68, arrangement: 'club', brightness: 0.20, noise: 0.05, dynamics: 0.55,
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covers: 'slowest track with a detectable beat — anchors the low tempo end' },
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{ name: 'elegy', bpm: 84, arrangement: 'ballad', brightness: 0.10, noise: 0.03, dynamics: 0.90,
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covers: 'slow, dark, one build and one payoff' },
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{ name: 'hymn', bpm: 92, arrangement: 'ballad', brightness: 0.80, noise: 0.20, dynamics: 0.70,
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covers: 'slow and bright — separates tempo from brightness' },
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{ name: 'still', bpm: 100, arrangement: 'sparse', brightness: 0.35, noise: 0.08, dynamics: 0.75,
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{ name: 'still', bpm: 100, arrangement: 'sparse', brightness: 0.35, noise: 0.06, dynamics: 0.75,
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covers: 'the degenerate two-section case, which must not break' },
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// --- mid tempo, the bulk of the space ---------------------------------
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{ name: 'dusk', bpm: 118, arrangement: 'classic', brightness: 0.15, noise: 0.05, dynamics: 0.60,
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covers: 'full arrangement, dark and tonal' },
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{ name: 'centre', bpm: 124, arrangement: 'classic', brightness: 0.50, noise: 0.20, dynamics: 0.55,
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{ name: 'dusk', bpm: 118, arrangement: 'classic', brightness: 0.02, noise: 0.01, dynamics: 0.60,
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covers: 'darkest and most tonal with a full arrangement' },
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{ name: 'centre', bpm: 124, arrangement: 'classic', brightness: 0.50, noise: 0.20, dynamics: 0.55,
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covers: 'the middle of every axis — the null hypothesis' },
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{ name: 'glare', bpm: 128, arrangement: 'classic', brightness: 0.90, noise: 0.55, dynamics: 0.50,
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{ name: 'glare', bpm: 128, arrangement: 'classic', brightness: 0.95, noise: 0.55, dynamics: 0.50,
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covers: 'bright and noisy together' },
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{ name: 'slab', bpm: 126, arrangement: 'club', brightness: 0.45, noise: 0.25, dynamics: 0.15,
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{ name: 'slab', bpm: 126, arrangement: 'club', brightness: 0.45, noise: 0.25, dynamics: 0.05,
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covers: 'limitered — lowest dynamic range, longest sections' },
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{ name: 'chrome', bpm: 132, arrangement: 'club', brightness: 0.80, noise: 0.15, dynamics: 0.35,
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{ name: 'chrome', bpm: 132, arrangement: 'club', brightness: 0.85, noise: 0.06, noiseColour: 0.1, dynamics: 0.35,
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covers: 'bright and tonal at club tempo' },
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{ name: 'murk', bpm: 88, arrangement: 'classic', brightness: 0.40, noise: 0.65, dynamics: 0.70,
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covers: 'noisy but dark — separates flatness from brightness' },
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{ name: 'murk', bpm: 88, arrangement: 'classic', brightness: 0.12, noise: 0.85, noiseColour: 0.95, dynamics: 0.70,
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covers: 'dark tonal content under bright hiss — the quadrant that breaks the brightness/noise correlation' },
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// --- fast, dense, broken ----------------------------------------------
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{ name: 'lattice', bpm: 140, arrangement: 'breaks', brightness: 0.60, noise: 0.40, dynamics: 0.45,
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{ name: 'lattice', bpm: 140, arrangement: 'breaks', brightness: 0.60, noise: 0.35, dynamics: 0.45,
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covers: 'most sections — makes rosters actually rotate' },
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{ name: 'grit', bpm: 150, arrangement: 'breaks', brightness: 0.25, noise: 0.70, dynamics: 0.40,
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covers: 'noisiest and dark — the corrupt director\'s home ground' },
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{ name: 'plate', bpm: 138, arrangement: 'club', brightness: 0.30, noise: 0.60, dynamics: 0.12,
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{ name: 'grit', bpm: 150, arrangement: 'breaks', brightness: 0.15, noise: 0.90, noiseColour: 0.85, dynamics: 0.40,
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covers: "noisiest and dark — the corrupt director's home ground" },
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{ name: 'plate', bpm: 138, arrangement: 'club', brightness: 0.25, noise: 0.70, noiseColour: 0.9, dynamics: 0.10,
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covers: 'noisy AND compressed — two extremes at once' },
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{ name: 'runner', bpm: 174, arrangement: 'breaks', brightness: 0.70, noise: 0.45, dynamics: 0.50,
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{ name: 'runner', bpm: 174, arrangement: 'breaks', brightness: 0.70, noise: 0.40, dynamics: 0.50,
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covers: 'fastest with a broken arrangement' },
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{ name: 'flare', bpm: 168, arrangement: 'classic', brightness: 0.95, noise: 0.80, dynamics: 0.30,
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{ name: 'flare', bpm: 168, arrangement: 'classic', brightness: 0.95, noise: 0.85, dynamics: 0.25,
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covers: 'brightest and noisiest — the far corner' },
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];
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@@ -93,6 +95,7 @@ export function song(name, { fps = 60 } = {}) {
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arrangement: spec.arrangement,
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brightness: spec.brightness,
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noise: spec.noise,
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noiseColour: spec.noiseColour ?? null,
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dynamics: spec.dynamics,
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seed: 1 + SONGS.indexOf(spec),
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}), { fps }),
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@@ -118,13 +121,20 @@ export function songBank({ count = null, fps = 60 } = {}) {
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export const AXES = [
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{ key: 'bpm', label: 'tempo', of: (t) => t.summary.bpm, range: [60, 180],
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reads: 'motion bias · animation rate · personality pace' },
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{ key: 'centroid', label: 'brightness', of: (t) => t.summary.meanCentroid, range: [0, 1],
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// Not [0,1]: centroid is mapped to a LOG frequency axis, so a track made of
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// nothing but sub-bass and a 55Hz pad still measures ~0.28 and pure hiss
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// measures ~0.9. The range here is what the statistic can really take on for
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// music, and calling it [0,1] would report a permanent 50% gap that no
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// synth change could close.
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{ key: 'centroid', label: 'brightness', of: (t) => t.summary.meanCentroid, range: [0.25, 0.95],
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reads: 'director odds · line weight · softness · bloom · vignette' },
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{ key: 'flatness', label: 'noisiness', of: (t) => t.summary.meanFlatness, range: [0, 1],
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reads: 'director odds · chroma · saturation · surface texture' },
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{ key: 'dynamics', label: 'dynamic range', of: (t) => t.summary.dynamicRange, range: [0, 1],
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reads: 'feedback amount and decay · contrast' },
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{ key: 'loudness', label: 'loudness', of: (t) => t.summary.meanLoudness, range: [0, 1],
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// Raw mean spectral magnitude, not a normalised 0..1 — biasFor divides
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// section energy by it, so its scale is whatever the analyser produces.
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{ key: 'loudness', label: 'loudness', of: (t) => t.summary.meanLoudness, range: [0, 0.012],
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reads: 'section energy · temperament intensity' },
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{ key: 'sections', label: 'section count', of: (t) => t.sections.length, range: [2, 9],
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reads: 'roster rotation · how often the image is allowed to change' },
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@@ -138,13 +138,19 @@ function addNoise(data, sampleRate, from, to, gain = 0.05, tilt = 0.5, seed = 12
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s0 = (Math.imul(s0 ^ (s0 >>> 15), s0 | 1) + 0x6d2b79f5) >>> 0;
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return ((s0 >>> 14) & 0xffff) / 0xffff - 0.5;
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};
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// One-pole: low coefficient keeps the lows, high coefficient keeps the highs.
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const a = 0.02 + tilt * 0.92;
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let lp = 0;
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// Two cascaded one-poles rather than one. A single pole is a 6dB/octave
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// slope, which leaves so much top on "dark" noise that a noisy track always
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// measured bright — the dark-and-noisy corner, which is the corrupt
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// director's entire home ground, was not reachable at all.
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const a = 0.004 + tilt * 0.9;
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let lp1 = 0, lp2 = 0;
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for (let s = start; s < end; s++) {
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const white = rnd();
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lp += a * (white - lp);
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data[s] += (tilt > 0.5 ? white - lp : lp) * gain * 2;
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lp1 += a * (white - lp1);
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lp2 += a * (lp1 - lp2);
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// Below half tilt the lowpass IS the signal; above it, what the lowpass
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// removed is.
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data[s] += (tilt > 0.5 ? white - lp2 : lp2 * 3) * gain * 2;
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}
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}
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@@ -246,6 +252,7 @@ export function synthesizeSong({
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arrangement = 'classic',
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brightness = 0.5,
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noise = 0.15,
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noiseColour = null,
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dynamics = 0.6,
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seed = 1,
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} = {}) {
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@@ -256,14 +263,40 @@ export function synthesizeSong({
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const right = buffer.getChannelData(1);
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const beat = 60 / bpm;
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// Low dynamics = a limitered master: quiet stages are pulled up toward the
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// loud ones rather than the loud ones being pulled down, so the track stays
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// audible and only its crest factor changes.
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const floor = 1 - dynamics;
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const level = (x) => floor + x * (1 - floor);
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const baseRoot = 90 + brightness * 180;
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const harmonics = Math.max(1, Math.round(1 + brightness * 6));
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// Dynamic range is measured as a crest factor — the 40th percentile of
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// frame RMS against the 95th — so moving it means changing the RATIO
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// between the quiet stages and the loud ones, not the overall level.
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//
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// A gamma on each stage's level relative to the loudest stage does that.
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// The loudest stage is pinned at its original value and everything below it
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// is pushed down (high dynamics) or pulled up (limitered), so a dynamic
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// track does not simply come out quieter — which is what a straight floor
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// offset did, and it moved the measured range by 0.2 across the whole bank.
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const gamma = 0.25 + dynamics * 3.2;
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// Percussion is transient, so a kick-driven track has a low RMS floor
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// between hits no matter how hard it is limitered — the gamma alone could
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// not get the measured range below 0.67. What actually fills the gaps is
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// SUSTAINED content, so the pad and the noise bed swell as dynamics falls.
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// That is also what a limitered master really sounds like.
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const sustainBoost = 1 + (1 - dynamics) ** 2 * 6;
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const peakOf = (field) => Math.max(...stages.map((s) => s[field] || 0), 1e-6);
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const peaks = { kick: peakOf('kick'), hat: peakOf('hat'), pad: peakOf('pad') };
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const level = (x, field) => (x <= 0 ? 0 : peaks[field] * (x / peaks[field]) ** gamma);
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// Brightness has to reach genuinely dark, and a hat is broadband: leaving
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// any hat in at brightness 0 held the measured centroid above 0.65 no matter
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// what the pad did. Below a quarter brightness the hats go entirely.
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const baseRoot = 55 + brightness * 260;
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const harmonics = Math.max(1, Math.round(1 + brightness ** 1.5 * 9));
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const hatPresence = Math.max(0, (brightness - 0.22) / 0.78);
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// The noise bed's COLOUR is its own axis, defaulting to the track's
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// brightness but separable from it. Tying the two together made spectral
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// flatness a function of centroid — measured across the bank they came out
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// at r = 0.95, one axis wearing two names, and the whole dark-but-noisy
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// quadrant was unreachable. Hiss over a sub-bass pad is an ordinary record.
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const tilt = 0.05 + (noiseColour === null ? brightness : noiseColour) * 0.9;
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let at = 0;
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let stageIndex = 0;
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@@ -276,25 +309,25 @@ export function synthesizeSong({
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let index = Math.round(from / beat);
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for (let t = from; t < to; t += beat, index++) {
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const ramp = stage.ramp ? (t - from) / Math.max(1e-6, to - from) : 1;
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const gain = level(stage.kick) * (0.25 + ramp * 0.75);
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if (stage.kick > 0.02 && gain > 0.02) {
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const gain = level(stage.kick, 'kick') * (0.25 + ramp * 0.75);
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if (stage.kick > 0.02 && gain > 0.005) {
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addKick(left, sampleRate, t, gain * (index % 4 === 0 ? 1 : 0.8));
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}
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if (stage.hat > 0.02) {
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const h = level(stage.hat) * ramp * (0.4 + brightness * 1.2);
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if (stage.hat > 0.02 && hatPresence > 0) {
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const h = level(stage.hat, 'hat') * ramp * hatPresence * 1.4;
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addHat(left, sampleRate, t + beat / 2, h, index + seed);
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if (h > 0.3) addHat(left, sampleRate, t + beat / 4, h * 0.6, index + seed + 7);
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}
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}
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addRichPad(left, sampleRate, from, to,
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level(stage.pad), baseRoot * stage.root, harmonics);
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level(stage.pad, 'pad') * sustainBoost, baseRoot * stage.root, harmonics);
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if (noise > 0.01) {
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// The bed follows the arrangement so it cannot flatten the dynamics
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// it is layered over.
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addNoise(left, sampleRate, from, to,
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noise * level(0.3 + stage.pad * 2), 0.15 + brightness * 0.8,
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(seed * 7919 + stageIndex) >>> 0);
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noise * level(stage.pad, 'pad') * 3 * sustainBoost,
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tilt, (seed * 7919 + stageIndex) >>> 0);
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}
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}
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