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Monorepo for Aesthetic.Computer aesthetic.computer
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JavaScript
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138// visual evidence. three claims, three pictures:// 1. the picture really is in the audio (independent spectrogram)// 2. a real photograph survives a simulated cassette// 3. the sync bug and its fix, measured across draws rather than once
import sharp from "sharp";import { createCanvas } from "canvas";import { writeFileSync, mkdirSync } from "node:fs";import { encode, decode } from "../lib/spectro.mjs";import { render } from "../lib/spectrogram.mjs";import { save, psnr, testcard } from "../lib/image.mjs";import * as C from "../lib/channel.mjs";
const OUT = "tapes/out";mkdirSync(OUT, { recursive: true });const opts = { n: 2048, spacing: 4 };const W = 240, H = 150;
async function grayscale(path) { const { data, info } = await sharp(path) .resize(W, H, { fit: "cover" }) .grayscale() .normalise() .raw() .toBuffer({ resolveWithObject: true }); const out = new Uint8Array(W * H * 4).fill(255); for (let i = 0; i < info.width * info.height; i += 1) { const v = data[i * info.channels]; out[i * 4] = out[i * 4 + 1] = out[i * 4 + 2] = v; } return { width: W, height: H, data: out };}
const photo = await grayscale("system/public/danzballet.studio/hero-pointe-shoes.jpg");const card = testcard(W, H);
// ── 1. the picture is in the audio ────────────────────────────────────────const { samples, plan: p } = encode(card, opts);const spec = render(samples, { n: 2048, hop: 1024, rate: p.rate });save(`${OUT}/proof-spectrogram.png`, spec);save(`${OUT}/proof-card.png`, card);save(`${OUT}/proof-card-decoded.png`, decode(samples, { width: W, height: H, ...opts }));console.log(`🔊 spectrogram ${spec.width}×${spec.height}, 0–${(spec.nyquist / 1000).toFixed(1)}kHz`);
// ── 2. a photograph down a cassette ───────────────────────────────────────const shots = [["source", (x) => x]];for (const [name, fn] of [ ["good deck", (x) => C.cassette(x, p.rate, { snr: 55, wow: 0.0006 })], ["walkman", (x) => C.cassette(x, p.rate, { snr: 45, wow: 0.003 })], ["worn tape", (x) => C.cassette(x, p.rate, { snr: 36, wow: 0.007 })], ["walkman → mp3 192", (x) => C.transcode(C.cassette(x, p.rate, { snr: 45, wow: 0.003 }), p.rate, C.codecs["mp3 192"])],]) shots.push([name, fn]);
const enc = encode(photo, opts);const photoRow = shots.map(([name, fn]) => { if (name === "source") return { name, img: photo, q: Infinity }; C.seed(0x5eed); const back = decode(fn(enc.samples), { width: W, height: H, ...opts }); return { name, img: back, q: psnr(photo, back) };});photoRow.forEach((r) => console.log(`📷 ${r.name.padEnd(20)} ${r.q === Infinity ? "source" : r.q.toFixed(2) + " dB"}`));
// ── 3. the sync bug, across draws ─────────────────────────────────────────const route = (x) => C.transcode(C.cassette(x, p.rate, { snr: 45, wow: 0.003 }), p.rate, C.codecs["mp3 192"]);const TRIALS = 8;
function measure(label, decodeOpts, encodeOpts) { const e = encode(card, { ...opts, ...encodeOpts }); const runs = C.trials(TRIALS, () => { const back = decode(route(e.samples), { width: W, height: H, ...opts, ...decodeOpts, ...encodeOpts }); return { back, drift: Math.abs(back.start - e.start), q: psnr(card, back) }; }); const lost = runs.filter((r) => r.drift > 64).length; console.log(`🔍 ${label.padEnd(34)} sync lost ${lost}/${TRIALS}`); return { label, lost, runs, trials: TRIALS };}
const before = measure("full-band PHAT, 0.15s chirp (bug)", { syncWide: true }, { chirpSecs: 0.15 });const after = measure("banded PHAT, 0.4s chirp (fixed)", {}, {});
// ── sheets ────────────────────────────────────────────────────────────────function sheet(path, rows, cellW, cellH) { const pad = 10, label = 18; const cols = Math.max(...rows.map((r) => r.cells.length)); const cw = cellW + pad, ch = cellH + label + pad + 14; const cv = createCanvas(cols * cw + pad, rows.length * ch + pad); const g = cv.getContext("2d"); g.fillStyle = "#0d0d10"; g.fillRect(0, 0, cv.width, cv.height); g.font = "12px monospace";
rows.forEach((row, ri) => { g.fillStyle = "#7bd"; g.fillText(row.title, pad, ri * ch + pad + 10); row.cells.forEach((cell, ci) => { const x = ci * cw + pad, y = ri * ch + pad + 16; const t = createCanvas(cell.img.width, cell.img.height); const id = t.getContext("2d").createImageData(cell.img.width, cell.img.height); id.data.set(cell.img.data); t.getContext("2d").putImageData(id, 0, 0); g.drawImage(t, x, y, cellW, cellH); g.fillStyle = cell.bad ? "#f77" : "#9e9"; g.fillText(cell.label, x, y + cellH + 13); }); }); writeFileSync(path, cv.toBuffer("image/png"));}
sheet( `${OUT}/proof-photo.png`, [{ title: "a photograph, encoded to audio and decoded back", cells: photoRow.map((r) => ({ img: r.img, label: `${r.name} ${r.q === Infinity ? "" : r.q.toFixed(1) + " dB"}` })) }], W, H,);
sheet( `${OUT}/proof-sync.png`, [before, after].map((m) => ({ title: `${m.label} — sync lost ${m.lost}/${m.trials}`, cells: m.runs.map((r, i) => ({ img: r.back, bad: r.drift > 64, label: r.drift > 64 ? `#${i} LOST` : `#${i} ${r.q.toFixed(1)}dB`, })), })), W, H,);
console.log(`\n🖼 ${OUT}/proof-spectrogram.png · proof-photo.png · proof-sync.png`);