open-standards/aac/aac-rs/tools/voices/render_samples.mjs

#!/usr/bin/env node
// Render each voice's sample: the voice, from the built packs, says its
// language's sample sentence (the catalogue's `sample_text`, set in
// build_voices.py SAMPLE_TEXT), which LAME encodes into
// tools/voices/samples/<pack>.mp3, recorded in samples/index.json.
//
// The samples are committed: synthesis is not repeatable (Piper samples its
// durations), so they are source files, rendered once and listened to before
// they ship. build_voices.py then pins and publishes them beside the voices,
// and the app plays one before the person decides to download its voice.
//
//   node tools/voices/render_samples.mjs            # voices whose sample is missing or stale
//   node tools/voices/render_samples.mjs --all      # every voice
//   node tools/voices/render_samples.mjs en-piper-cori de
//   node tools/voices/render_samples.mjs --out DIR  # packs elsewhere
//
// Needs Node >= 22 and LAME (brew install lame). A sample that is silent,
// under 1 s or over 8 s is not written: listen to that voice, and to every
// sample before committing it.
import crypto from 'node:crypto';
import { execFileSync } from 'node:child_process';
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import { fileURLToPath, pathToFileURL } from 'node:url';

const HERE = path.dirname(fileURLToPath(import.meta.url));
const SAMPLES = path.join(HERE, 'samples');
// Mono MPEG-2 layer III at 32 kbit/s, 24 kHz: about 4 KB a second, clear
// speech, and decoded by every browser the app supports (the open-source
// Chromium the tests use has no AAC). LAME's output is repeatable.
const LAME_ARGS = ['--quiet', '-m', 'm', '-b', '32', '--resample', '24', '--noreplaygain', '-q', '0'];
// Keep peaks at -1 dBFS: the voices reach full scale, which clips once encoded.
const PEAK = 0.89;

let out = process.env.AAC_VOICES_DIR || path.resolve(HERE, '../../../../../aac-voice-packs');
let all = false;
const only = [];
const argv = process.argv.slice(2);
for (let i = 0; i < argv.length; i++) {
  if (argv[i] === '--out') out = path.resolve(argv[++i]);
  else if (argv[i] === '--all') all = true;
  else only.push(argv[i]);
}

const lameVersion = execFileSync('lame', ['--version']).toString().split('\n')[0].trim();
const pointer = JSON.parse(fs.readFileSync(path.join(out, 'index.json'), 'utf8'));
const cat = JSON.parse(fs.readFileSync(path.join(out, pointer.current), 'utf8'));
if (cat.schema !== 'aac-voice-index/1') throw new Error(`unknown schema ${cat.schema}`);
fs.mkdirSync(SAMPLES, { recursive: true });
const indexPath = path.join(SAMPLES, 'index.json');
const index = fs.existsSync(indexPath) ? JSON.parse(fs.readFileSync(indexPath, 'utf8')) : {};

const bytes = (f) => new Uint8Array(fs.readFileSync(path.join(out, f.url)));
const sha256 = (data) => crypto.createHash('sha256').update(data).digest('hex');
const runtimes = new Map();
async function runtime(id) {
  if (!runtimes.has(id)) {
    const rt = cat.runtimes[id];
    const { default: createModule } = await import(pathToFileURL(path.join(out, rt.module)).href);
    runtimes.set(id, await createModule({ wasmBinary: fs.readFileSync(path.join(out, rt.wasm)), print: () => {}, printErr: () => {} }));
  }
  return runtimes.get(id);
}

function wav(audio, sr) {
  const b = Buffer.alloc(44 + audio.length * 2);
  b.write('RIFF', 0); b.writeUInt32LE(36 + audio.length * 2, 4); b.write('WAVEfmt ', 8);
  b.writeUInt32LE(16, 16); b.writeUInt16LE(1, 20); b.writeUInt16LE(1, 22); b.writeUInt32LE(sr, 24);
  b.writeUInt32LE(sr * 2, 28); b.writeUInt16LE(2, 32); b.writeUInt16LE(16, 34); b.write('data', 36);
  b.writeUInt32LE(audio.length * 2, 40);
  for (let i = 0; i < audio.length; i++) b.writeInt16LE(Math.max(-32768, Math.min(32767, Math.round(audio[i] * 32767))), 44 + i * 2);
  return b;
}

const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'aac-samples-'));
const failures = [];
let rendered = 0;
for (const [code, lang] of Object.entries(cat.languages)) {
  for (const pack of lang.packs) {
    const text = pack.sample_text;
    if (!text) continue;
    if (only.length && !only.includes(pack.id) && !only.includes(code)) continue;
    const file = path.join(SAMPLES, `${pack.id}.mp3`);
    const current = index[pack.id]?.text === text && fs.existsSync(file) && sha256(fs.readFileSync(file)) === index[pack.id]?.sha256;
    if (current && !all && !only.length) continue;

    const m = await runtime(pack.runtime);
    const files = [...pack.requires.flatMap((c) => cat.components[c].files), ...pack.files];
    const tts = new m.TextToSpeech(pack.lang_key, files.map((f) => f.name), files.map(bytes), Object.keys(pack.options), Object.values(pack.options));
    const r = tts.say(text);
    tts.delete?.();
    const audio = Float32Array.from(r.audio);
    const seconds = audio.length / r.sampleRate;
    let peak = 0, sum = 0;
    for (const x of audio) { peak = Math.max(peak, Math.abs(x)); sum += x * x; }
    const rms = Math.sqrt(sum / Math.max(1, audio.length));
    if (seconds < 1 || seconds > 8 || rms < 0.01) {
      failures.push(`${pack.id}: ${seconds.toFixed(2)} s, rms ${rms.toFixed(3)}: listen to this voice`);
      continue;
    }
    if (peak > PEAK) for (let i = 0; i < audio.length; i++) audio[i] *= PEAK / peak;
    const wavPath = path.join(tmp, `${pack.id}.wav`);
    fs.writeFileSync(wavPath, wav(audio, r.sampleRate));
    execFileSync('lame', [...LAME_ARGS, wavPath, file]);
    const mp3 = fs.readFileSync(file);
    index[pack.id] = {
      text,
      sha256: sha256(mp3),
      bytes: mp3.length,
      seconds: Number(seconds.toFixed(2)),
      tool: `${lameVersion}: ${LAME_ARGS.join(' ')}; peak limited to ${PEAK}`,
    };
    rendered++;
    console.log(`ok   ${pack.id.padEnd(26)} ${seconds.toFixed(2)} s, ${(mp3.length / 1024).toFixed(1)} KB  ${file}`);
  }
}
fs.rmSync(tmp, { recursive: true, force: true });
const sorted = Object.fromEntries(Object.keys(index).sort().map((k) => [k, index[k]]));
fs.writeFileSync(indexPath, JSON.stringify(sorted, null, 2) + '\n');
console.log(`\n${rendered} sample(s) rendered into ${SAMPLES}; listen to each before committing.`);
if (failures.length) {
  console.error(failures.map((f) => `FAIL ${f}`).join('\n'));
  process.exit(1);
}
process.exit(0);