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Monorepo for Aesthetic.Computer aesthetic.computer
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JavaScript
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103// bus.mjs — buffer-mock-synth that implements the AC `sound.synth(...)`// contract over a Float32Array buffer. Lets server-side renderers drive// the same synthesis calls that the web AudioContext + fedac/native// audio.c implement, so a single voice description plays identically// everywhere.//// Contract (matches the AC web/native runtime):// sound.synth({// type: "sine" | "square" | "triangle" | "sawtooth" | "noise"// tone: Hz// duration: seconds// volume: scalar (0..1+)// attack: seconds (linear)// decay: seconds (exponential tail after attack)// pan: -1..1 (ignored in mono out)// phase: optional 0..1 initial phase (additive AC extension —// native runtimes that don't honor it default to 0)// })//// Total event length = max(duration, attack + decay).
const DEFAULT_SAMPLE_RATE = 48_000;
export function makeBufferSynth(out, startSec, sampleRate = DEFAULT_SAMPLE_RATE, noiseRng = Math.random) { return { synth: (params) => { const type = params?.type || "sine"; const tone = Number(params?.tone) || 440; const duration = Number(params?.duration); const volume = Number(params?.volume ?? 1); const attack = Math.max(0, Number(params?.attack ?? 0.001)); const decay = Number.isFinite(params?.decay) ? Math.max(0, Number(params.decay)) : Math.max(0.001, (Number.isFinite(duration) ? duration : 0.05) - attack); const initPhase = Number.isFinite(params?.phase) ? params.phase : 0; if (!Number.isFinite(volume) || volume === 0) return null; if (!Number.isFinite(duration) || duration <= 0) return null;
const durSamples = Math.ceil(duration * sampleRate); const attS = Math.max(1, Math.floor(attack * sampleRate)); const decS = Math.max(1, Math.floor(decay * sampleRate)); // Match fedac/native/src/audio.c compute_envelope(): // linear attack (0 → 1 over `attack` seconds) // hold at 1 until `duration - decay` // linear decay (1 → 0 over `decay` seconds ending at duration) // When attack + decay > duration, native clamps decay_start to 0 // (so the decay starts immediately after attack, truncated at // duration). We instead AUTO-EXTEND the window to attack+decay so // the envelope completes to true silence without clicks at end — // matches the AC web AudioContext + ADSR-style releases. const ns = Math.max(durSamples, attS + decS); const decayStart = ns - decS; // >= attS by construction (attS + decS <= ns) const startIdx = Math.floor(startSec * sampleRate); const omega = (2 * Math.PI * tone) / sampleRate; const phaseInc = tone / sampleRate;
// SVF bandpass for noise voices (matches trap.mjs / percussion fan-out). const fcSafe = Math.min(Math.max(40, tone), sampleRate / 6); const fParam = 2 * Math.sin(Math.PI * fcSafe / sampleRate); const damp = 1 / 4; let svfLow = 0, svfBand = 0;
let phaseAcc = initPhase;
for (let i = 0; i < ns; i++) { const dst = startIdx + i; if (dst < 0 || dst >= out.length) continue;
// Native-portable envelope: linear attack → hold → linear decay. let env; if (i < attS) { env = i / attS; } else if (i < decayStart) { env = 1; } else { env = 1 - (i - decayStart) / decS; if (env <= 0) continue; }
let s; switch (type) { case "sine": s = Math.sin(omega * i + 2 * Math.PI * initPhase); break; case "square": s = Math.sin(omega * i + 2 * Math.PI * initPhase) >= 0 ? 1 : -1; break; case "triangle": { const ph = (phaseAcc + i * phaseInc) % 1; s = ph < 0.5 ? 4 * ph - 1 : 3 - 4 * ph; break; } case "sawtooth": { const ph = (phaseAcc + i * phaseInc) % 1; s = 2 * ph - 1; break; } case "noise": case "noise-white": { const w = noiseRng() * 2 - 1; const high = w - svfLow - damp * svfBand; svfBand += fParam * high; svfLow += fParam * svfBand; s = svfBand * 1.5; break; } default: s = 0; } out[dst] += s * env * volume; } return null; }, };}