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webasmr / tts.worker.js
Custom WGSL DiT engine (int4, CFG-free 4-step)
db4a2ce 8 days ago
23.2 kB
import * as ort from './ort/ort.mjs';
import { F5Engine } from './engine/f5engine.js';

const SAMPLE_RATE = 24000;
const MEL_BINS = 100;
const CFG_STRENGTH = 2;
let cfgStrength = CFG_STRENGTH;
const N_FFT = 1024;
const HOP = 256;
const SPEC_BINS = N_FFT / 2 + 1;
const DEFAULT_BASE = '/models/f5tts';
const DEFAULT_STEPS = 32;
const MAX_REF_FRAMES = 768;
const MIN_GEN_FRAMES = 16;
const MAX_GEN_FRAMES = 640;
const TARGET_RMS = 0.1;
let refTextEncoder = null;
let engine = null;
let engineDevice = null;

ort.env.wasm.wasmPaths = '/ort/';
ort.env.wasm.numThreads = Math.min(8, Math.max(1, (self.navigator?.hardwareConcurrency || 4) - 1));
ort.env.logLevel = 'warning';

let base = DEFAULT_BASE;
let manifest = null;
let ditSession = null;
let vocoderSession = null;
let tuning = null;
let vocab = null;
let pinyin = null;
let caps = null;
const voiceCache = new Map();

const post = (msg, transfer) => self.postMessage(msg, transfer || []);
const reply = (msg, nonce) => post({ ...msg, __nonce: nonce });

function progress(stage, data = {}) {
  post({ type: 'progress', stage, ...data });
}

async function fetchJson(url) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`asset missing: ${url} (${res.status})`);
  return res.json();
}

async function probeCaps() {
  if (caps) return caps;
  const result = { webgpu: false };
  try {
    const gpu = navigator.gpu;
    if (!gpu) return (caps = result);
    const adapter = await gpu.requestAdapter({ powerPreference: 'high-performance' });
    if (!adapter) return (caps = result);
    const info = adapter.info || {};
    const has = (f) => { try { return adapter.features.has(f); } catch { return false; } };
    caps = {
      webgpu: true,
      vendor: info.vendor || '',
      architecture: info.architecture || '',
      description: info.description || '',
      isFallback: adapter.isFallbackAdapter === true,
      shaderF16: has('shader-f16'),
      subgroups: has('subgroups'),
      timestampQuery: has('timestamp-query'),
      crossOriginIsolated: self.crossOriginIsolated === true,
      numThreads: ort.env.wasm.numThreads,
    };
  } catch {
    caps = result;
  }
  return caps;
}

async function loadTuning() {
  if (tuning) return tuning;
  const defaults = { llm: { maxTokens: 256, temperature: 0.7, prefillChunk: 512 }, tts: { flowSteps: DEFAULT_STEPS }, session: { preferPrecision: 'auto' } };
  try {
    const res = await fetch('/tuning.json');
    const type = res.headers.get('content-type') || '';
    tuning = res.ok && type.includes('json') ? { ...defaults, ...(await res.json()) } : defaults;
  } catch {
    tuning = defaults;
  }
  return tuning;
}

// Download a graph with byte progress (falls back to plain fetch when streams are unavailable).
async function fetchModel(url, label) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`failed to download ${label}: ${url} (${res.status})`);
  const total = Number(res.headers.get('content-length') || 0);
  if (!res.body || !res.body.getReader) return { data: new Uint8Array(await res.arrayBuffer()), total: 0 };
  const reader = res.body.getReader();
  const chunks = [];
  let loaded = 0;
  let lastPost = 0;
  for (;;) {
    const { done, value } = await reader.read();
    if (done) break;
    chunks.push(value);
    loaded += value.length;
    const now = performance.now();
    if (now - lastPost > 100) { progress('download', { label, loaded, total }); lastPost = now; }
  }
  progress('download', { label, loaded, total });
  const data = new Uint8Array(loaded);
  let offset = 0;
  for (const chunk of chunks) { data.set(chunk, offset); offset += chunk.length; }
  return { data, total: loaded };
}

async function createSession(url, label, executionProviders) {
  const started = performance.now();
  progress('session', { label, message: `fetching ${label}` });
  const { data, total } = await fetchModel(url, label);
  progress('session', { label, message: `initializing ${label} (${(total / 1e6).toFixed(0)} MB)`, loaded: total, total });
  const session = await ort.InferenceSession.create(data, {
    executionProviders,
    graphOptimizationLevel: executionProviders.includes('webgpu') ? 'basic' : 'all',
  });
  progress('session', { label, message: `${label} ready in ${((performance.now() - started) / 1000).toFixed(1)}s`, done: true });
  return session;
}

async function initEngine() {
  const want = (tuning?.tts?.backend ?? 'engine') === 'engine';
  if (!want) return;
  const info = await probeCaps();
  if (!info.webgpu || !info.shaderF16) return;
  try {
    const adapter = await navigator.gpu.requestAdapter({ powerPreference: 'high-performance' });
    if (!adapter) return;
    const feats = ['shader-f16'];
    let sgmat = false;
    try { sgmat = adapter.features.has('chromium-experimental-subgroup-matrix'); } catch {}
    if (sgmat) feats.push('chromium-experimental-subgroup-matrix');
    const device = await adapter.requestDevice({
      requiredFeatures: feats,
      requiredLimits: {
        maxStorageBufferBindingSize: adapter.limits.maxStorageBufferBindingSize,
        maxBufferSize: adapter.limits.maxBufferSize,
        maxComputeWorkgroupStorageSize: adapter.limits.maxComputeWorkgroupStorageSize,
      },
    });
    engineDevice = device;
    engine = await F5Engine.create(device, {
      gemm: tuning?.tts?.gemm || (sgmat ? 'sgmat' : 'simt'),
      branches: 1,
      metaUrl: `${base}/f5w_q4.json`,
      binUrl: `${base}/f5w_q4.bin`,
    });
    progress('session', { message: 'DiT kernels ready (WebGPU)' });
  } catch (err) {
    engine = null;
    engineDevice = null;
    progress('fallback', { message: `engine unavailable, using ORT: ${err?.message || err}` });
  }
}

async function loadGraphs() {
  if (engine) {
    if (!vocoderSession) {
      const g = manifest.graphs || {};
      vocoderSession = await createSession(`${base}/${g.vocoder_fp16 || g.vocoder}`, 'vocoder · WebGPU', ['webgpu', 'wasm']);
    }
    return;
  }
  if (ditSession && vocoderSession) return;
  const graphs = manifest.graphs || {};
  const fp16Available = !!(graphs.dit_step_fp16 && graphs.vocoder_fp16);
  const info = await probeCaps();
  const tryGpu = info.webgpu && fp16Available;

  if (tryGpu) {
    progress('session', { message: 'WebGPU detected — loading fp16 graphs' });
    try {
      ditSession = await createSession(`${base}/${graphs.dit_step_fp16}`, 'dit · fp16 · WebGPU', ['webgpu', 'wasm']);
    } catch (err) {
      progress('fallback', { message: `webgpu dit failed, falling back to wasm: ${err?.message || err}` });
    }
    try {
      vocoderSession = await createSession(`${base}/${graphs.vocoder_fp16}`, 'vocoder · fp16 · WebGPU', ['webgpu', 'wasm']);
    } catch (err) {
      progress('fallback', { message: `webgpu vocoder failed, falling back to wasm: ${err?.message || err}` });
    }
  }
  if (!ditSession) {
    ditSession = await createSession(`${base}/${graphs.dit_step}`, 'dit · int8 · WASM', ['wasm']);
  }
  if (!vocoderSession) {
    vocoderSession = await createSession(`${base}/${graphs.vocoder}`, 'vocoder · int8 · WASM', ['wasm']);
  }
}

async function warmup() {
  const frames = tuning?.tts?.warmupFrames ?? manifest.vocoder_chunk_frames ?? 375;
  if (!engine) await runAndDispose(ditSession, () => ditInputs(null, frames, 16, null, null, null));
  await runAndDispose(vocoderSession, () => ({ mel: f16Tensor(new Float32Array(MEL_BINS * frames), [1, MEL_BINS, frames]) }));
}

async function runAndDispose(session, feeds) {
  const inputs = feeds();
  try {
    const outputs = await session.run(inputs);
    disposeAll(outputs);
  } finally {
    disposeAll(inputs);
  }
}

// ---------------------------------------------------------------------------
// Text → token ids (ASCII + numbered pinyin, no CJK glyphs in the vocab)
// ---------------------------------------------------------------------------

const isCjk = (ch) => { const cp = ch.codePointAt(0); return cp >= 12544 && cp <= 40959; };
const asciiWord = /[A-Za-z0-9]+/y;
const QUOTE_MAP = { '；': ',', '，': ',', '“': '"', '”': '"', '‘': "'", '’': "'" };

function splitText(text, pinyinMap) {
  const normalized = Array.from(String(text ?? ''), (ch) => QUOTE_MAP[ch] ?? ch).join('');
  const tokens = [];
  let i = 0;
  while (i < normalized.length) {
    if (isCjk(normalized[i])) {
      while (i < normalized.length && isCjk(normalized[i])) {
        const ch = normalized[i];
        tokens.push(' ');
        tokens.push(pinyinMap[ch] ?? ch);
        i += 1;
      }
      continue;
    }
    asciiWord.lastIndex = i;
    const word = asciiWord.exec(normalized);
    if (word && word.index === i && word[0].length > 1) {
      const prev = tokens.length ? tokens[tokens.length - 1] : '';
      if (tokens.length && !` :'"`.includes(prev)) tokens.push(' ');
      tokens.push(...Array.from(word[0]));
      i += word[0].length;
      continue;
    }
    tokens.push(normalized[i]);
    i += 1;
  }
  return tokens;
}

async function loadVocab() {
  if (!vocab) vocab = await fetchJson(`${base}/vocab.json`);
  return vocab;
}

async function loadPinyin() {
  if (!pinyin) pinyin = await fetchJson(`${base}/pinyin.json`);
  return pinyin;
}

async function tokenize(text) {
  const [vocabData, pinyinMap] = await Promise.all([loadVocab(), loadPinyin()]);
  const tokens = splitText(text, pinyinMap);
  const ids = new Int32Array(tokens.length);
  const unknown = [];
  for (let i = 0; i < tokens.length; i++) {
    const token = tokens[i];
    if (token === ' ' || vocabData.index[token] !== undefined) {
      ids[i] = vocabData.index[token];
      continue;
    }
    if (isCjk(token[0]) && !unknown.includes(token[0])) unknown.push(token[0]);
    ids[i] = 0;
  }
  return { ids, unknown };
}

// ---------------------------------------------------------------------------
// Voice reference (mel spectrogram, fp16)
// ---------------------------------------------------------------------------

async function loadVoice(voiceId) {
  const id = voiceId || 'xiaochun';
  if (voiceCache.has(id)) return voiceCache.get(id);
  let meta;
  let raw;
  try {
    meta = await fetchJson(`/refs/${id}.json`);
    raw = await (await fetch(`/${meta.mel_file}`)).arrayBuffer();
  } catch {
    meta = await fetchJson(`${base}/refs/${id}.json`);
    raw = await (await fetch(`${base}/${meta.mel_file}`)).arrayBuffer();
  }
  const halves = new Float16Array(raw);
  const mel = new Float32Array(halves.length);
  for (let i = 0; i < halves.length; i++) mel[i] = halves[i];
  const [bins, frames] = meta.mel_shape;
  const voice = { id: meta.id, nameZh: meta.name_zh, mel, bins, frames, refText: meta.ref_text, seconds: meta.seconds };
  voiceCache.set(id, voice);
  return voice;
}

// ---------------------------------------------------------------------------
// Flow matching (Euler + sway schedule + classifier-free guidance)
// ---------------------------------------------------------------------------

function flowSchedule(steps, sway = -1) {
  const t = new Float64Array(steps + 1);
  for (let i = 0; i <= steps; i++) t[i] = i / steps;
  if (sway != null) {
    for (let i = 0; i <= steps; i++) t[i] += sway * (Math.cos((Math.PI / 2) * t[i]) - 1 + t[i]);
  }
  return t;
}

function gaussianNoise(frames, bins, seed = 1234) {
  let state = seed >>> 0;
  const next = () => {
    state ^= state << 13; state >>>= 0;
    state ^= state >> 17;
    state ^= state << 5; state >>>= 0;
    return state / 4294967296;
  };
  const out = new Float32Array(frames * bins);
  for (let i = 0; i < out.length; i += 2) {
    const u = Math.max(next(), 1e-7);
    const v = next();
    const r = Math.sqrt(-2 * Math.log(u));
    out[i] = r * Math.cos(2 * Math.PI * v);
    if (i + 1 < out.length) out[i + 1] = r * Math.sin(2 * Math.PI * v);
  }
  return out;
}

function flowSample(stepFn, frames, bins, { steps = DEFAULT_STEPS, sway = -1, seed = 1234, onStep } = {}) {
  const schedule = flowSchedule(steps, sway);
  const x = gaussianNoise(frames, bins, seed);
  const dt = new Float32Array(steps);
  for (let i = 0; i < steps; i++) dt[i] = schedule[i + 1] - schedule[i];
  return (async () => {
    for (let i = 0; i < steps; i++) {
      const velocity = await stepFn(x, schedule[i]);
      for (let j = 0; j < x.length; j++) x[j] += dt[i] * velocity[j];
      onStep?.(i + 1, steps);
    }
    return x;
  })();
}

// ---------------------------------------------------------------------------
// Model inference plumbing (fp16 tensors)
// ---------------------------------------------------------------------------

function f16Array(src) {
  const out = new Float16Array(src.length);
  for (let i = 0; i < src.length; i++) out[i] = src[i];
  return out;
}

function f16Tensor(data, dims) {
  return new ort.Tensor('float16', f16Array(data), dims);
}

function toFloat32(data) {
  if (data instanceof Float16Array) return Float32Array.from(data);
  if (data instanceof Uint16Array) {
    const out = new Float32Array(data.length);
    for (let i = 0; i < data.length; i++) {
      const bits = data[i];
      const sign = (bits & 0x8000) ? -1 : 1;
      const exponent = (bits >> 10) & 0x1f;
      const mantissa = bits & 0x3ff;
      if (exponent === 0) out[i] = sign * Math.pow(2, -14) * (mantissa / 1024);
      else if (exponent === 0x1f) out[i] = mantissa ? NaN : sign * Infinity;
      else out[i] = sign * Math.pow(2, exponent - 15) * (1 + mantissa / 1024);
    }
    return out;
  }
  return data;
}

function ditInputs(x, frames, textLen, cond, textIds, time) {
  const condData = cond ?? new Float32Array(frames * MEL_BINS);
  const ids = BigInt64Array.from({ length: textLen }, (_, i) => BigInt(textIds?.[i] ?? -1));
  return {
    x: f16Tensor(x ?? new Float32Array(frames * MEL_BINS), [1, frames, MEL_BINS]),
    cond: f16Tensor(condData, [1, frames, MEL_BINS]),
    text_ids: new ort.Tensor('int64', ids, [1, textLen]),
    time: f16Tensor(Float32Array.from([time ?? 0]), [1]),
    mask: new ort.Tensor('bool', new Uint8Array(frames).fill(1), [1, frames]),
  };
}

function disposeAll(tensors) {
  for (const tensor of Object.values(tensors)) tensor?.dispose?.();
}

function padReference(voice, refFrames, frames) {
  const out = new Float32Array(frames * MEL_BINS);
  for (let f = 0; f < refFrames; f++) {
    for (let b = 0; b < MEL_BINS; b++) {
      out[f * MEL_BINS + b] = voice.mel[b * voice.frames + f];
    }
  }
  return out;
}

async function ditStep(x, time, voice, textIds, textLen, frames, refFrames) {
  const condFeeds = ditInputs(x, frames, textLen, padReference(voice, refFrames, frames), textIds, time);
  const gen = await ditSession.run(condFeeds);
  const pred = toFloat32(gen.velocity.data);
  disposeAll(gen);
  disposeAll(condFeeds);
  if (cfgStrength === 0) return pred;
  const nullFeeds = ditInputs(x, frames, textLen, null, null, time);
  const uncond = await ditSession.run(nullFeeds);
  const nullPred = toFloat32(uncond.velocity.data);
  disposeAll(uncond);
  disposeAll(nullFeeds);
  const velocity = new Float32Array(pred.length);
  for (let i = 0; i < pred.length; i++) velocity[i] = pred[i] + (pred[i] - nullPred[i]) * cfgStrength;
  return velocity;
}

// ---------------------------------------------------------------------------
// Vocoder tail: magnitude/phase planes → inverse STFT (1024/256, hann, centered)
// ---------------------------------------------------------------------------

let twiddleCos = null;
let twiddleSin = null;
let hannWindow = null;

function initIstftTables() {
  if (twiddleCos) return;
  twiddleCos = new Float64Array(N_FFT / 2);
  twiddleSin = new Float64Array(N_FFT / 2);
  for (let i = 0; i < N_FFT / 2; i++) {
    twiddleCos[i] = Math.cos((2 * Math.PI * i) / N_FFT);
    twiddleSin[i] = Math.sin((2 * Math.PI * i) / N_FFT);
  }
  hannWindow = new Float64Array(N_FFT);
  for (let i = 0; i < N_FFT; i++) hannWindow[i] = 0.5 - 0.5 * Math.cos((2 * Math.PI * i) / N_FFT);
}

function ifft(re, im, out) {
  initIstftTables();
  const reFull = new Float64Array(N_FFT);
  const imFull = new Float64Array(N_FFT);
  for (let i = 0; i < SPEC_BINS; i++) { reFull[i] = re[i]; imFull[i] = im[i]; }
  for (let i = SPEC_BINS; i < N_FFT; i++) { reFull[i] = reFull[N_FFT - i]; imFull[i] = -imFull[N_FFT - i]; }
  for (let i = 1, j = 0; i < N_FFT; i++) {
    let bit = N_FFT >> 1;
    for (; j & bit; bit >>= 1) j ^= bit;
    j ^= bit;
    if (i < j) {
      let tmp = reFull[i]; reFull[i] = reFull[j]; reFull[j] = tmp;
      tmp = imFull[i]; imFull[i] = imFull[j]; imFull[j] = tmp;
    }
  }
  for (let size = 2; size <= N_FFT; size <<= 1) {
    const half = size >> 1;
    const step = N_FFT / size;
    for (let start = 0; start < N_FFT; start += size) {
      for (let k = 0; k < half; k++) {
        const angle = k * step;
        const wr = twiddleCos[angle];
        const wi = twiddleSin[angle];
        const a = start + k;
        const b = a + half;
        const tr = reFull[b] * wr - imFull[b] * wi;
        const ti = reFull[b] * wi + imFull[b] * wr;
        reFull[b] = reFull[a] - tr;
        imFull[b] = imFull[a] - ti;
        reFull[a] += tr;
        imFull[a] += ti;
      }
    }
  }
  for (let i = 0; i < N_FFT; i++) out[i] = reFull[i] / N_FFT;
}

function istft(planes, frames) {
  initIstftTables();
  const length = (frames - 1) * HOP + N_FFT;
  const acc = new Float64Array(length);
  const norm = new Float64Array(length);
  const re = new Float64Array(SPEC_BINS);
  const im = new Float64Array(SPEC_BINS);
  const frame = new Float64Array(N_FFT);
  for (let t = 0; t < frames; t++) {
    for (let b = 0; b < SPEC_BINS; b++) {
      const mag = Math.min(Math.exp(planes[b * frames + t]), 100);
      const phase = planes[SPEC_BINS * frames + b * frames + t];
      re[b] = mag * Math.cos(phase);
      im[b] = mag * Math.sin(phase);
    }
    ifft(re, im, frame);
    const offset = t * HOP;
    for (let i = 0; i < N_FFT; i++) {
      acc[offset + i] += frame[i] * hannWindow[i];
      norm[offset + i] += hannWindow[i] * hannWindow[i];
    }
  }
  const trim = N_FFT >> 1;
  const out = new Float32Array(length - 2 * trim);
  for (let i = 0; i < out.length; i++) {
    const d = norm[i + trim];
    out[i] = d > 1e-11 ? acc[i + trim] / d : 0;
  }
  return out;
}

async function decodeMel(mel, frames) {
  const chunkFrames = manifest.vocoder_chunk_frames || 375;
  const chunks = [];
  for (let start = 0; start < frames; start += chunkFrames) {
    const len = Math.min(chunkFrames, frames - start);
    const input = new Float32Array(MEL_BINS * len);
    for (let b = 0; b < MEL_BINS; b++) {
      for (let f = 0; f < len; f++) input[b * len + f] = mel[(start + f) * MEL_BINS + b];
    }
    const feeds = { mel: f16Tensor(input, [1, MEL_BINS, len]) };
    const outputs = await vocoderSession.run(feeds);
    const planes = toFloat32(outputs.stft_planes.data);
    disposeAll(outputs);
    disposeAll(feeds);
    chunks.push(istft(planes, len));
  }
  const total = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
  const pcm = new Float32Array(total);
  let offset = 0;
  for (const chunk of chunks) { pcm.set(chunk, offset); offset += chunk.length; }
  return pcm;
}

// ---------------------------------------------------------------------------
// Message handling
// ---------------------------------------------------------------------------

async function init(message) {
  if (message.base) base = message.base;
  await loadTuning();
  manifest = await fetchJson(`${base}/manifest.json`);
  await initEngine();
  await loadGraphs();
  progress('warmup', { message: 'warming up kernels' });
  await warmup();
  await loadVoice('xiaochun').catch(() => {});
  post({ type: 'caps', caps: await probeCaps() });
}

const refIdCache = new Map();

async function getRefIds(voice) {
  if (!voice.refText) return [];
  if (!refIdCache.has(voice.id)) {
    const { ids } = await tokenize(voice.refText);
    refIdCache.set(voice.id, Array.from(ids));
  }
  return refIdCache.get(voice.id);
}

async function synthesize(message) {
  if ((!engine && !ditSession) || !vocoderSession) throw new Error('worker not initialized');
  const started = performance.now();
  const { ids: genIds, unknown } = await tokenize(message.text);
  if (!genIds.length) throw new Error(`no vocab tokens for: ${String(message.text).slice(0, 20)}`);
  const voice = await loadVoice(message.voiceId);
  const refIds = await getRefIds(voice);
  const ids = [...refIds, ...genIds];
  const refFrames = Math.min(voice.frames, MAX_REF_FRAMES);
  refTextEncoder ??= new TextEncoder();
  const refBytes = Math.max(refTextEncoder.encode(voice.refText || '').length, 1);
  const genBytes = Math.max(refTextEncoder.encode(message.text).length, 1);
  let genFrames = Math.round((refFrames / refBytes) * genBytes);
  genFrames = Math.max(Math.min(genFrames, MAX_GEN_FRAMES), MIN_GEN_FRAMES);
  const frames = refFrames + genFrames;
  const textLen = Math.min(ids.length, frames);
  cfgStrength = tuning?.tts?.cfgStrength ?? manifest.sampler?.cfg_strength ?? CFG_STRENGTH;
  const steps = tuning?.tts?.flowSteps ?? manifest.sampler?.steps ?? DEFAULT_STEPS;
  progress('synth', { message: 'flow matching', step: 0, steps });
  let mel;
  if (engine) {
    engine.setup(frames);
    await engine.setCond(padReference(voice, refFrames, frames), ids);
    engine.setX(gaussianNoise(frames, MEL_BINS, message.seed ?? 1234));
    await engineDevice.queue.onSubmittedWorkDone();
    const sched = flowSchedule(steps, manifest.sampler?.sway_sampling_coef ?? -1);
    for (let i = 0; i < steps; i++) {
      progress('synth', { step: i + 1, steps, message: `flow step ${i + 1}/${steps}` });
      await engine.step(sched[i], sched[i + 1] - sched[i]);
    }
    mel = await engine.readX();
  } else {
    mel = await flowSample(
      (x, time) => ditStep(x, time, voice, ids, textLen, frames, refFrames),
      frames,
      MEL_BINS,
      {
        steps,
        sway: manifest.sampler?.sway_sampling_coef ?? -1,
        seed: message.seed ?? 1234,
        onStep: (step, total) => progress('synth', { step, steps: total, message: `flow step ${step}/${total}` }),
      },
    );
  }
  progress('synth', { message: 'vocoding', step: steps, steps });
  const pcm = await decodeMel(mel.subarray(refFrames * MEL_BINS), genFrames);
  let sum = 0;
  for (let i = 0; i < pcm.length; i++) sum += pcm[i] * pcm[i];
  const rms = Math.sqrt(sum / Math.max(pcm.length, 1));
  if (rms > 1e-6) {
    const scale = TARGET_RMS / rms;
    for (let i = 0; i < pcm.length; i++) pcm[i] *= scale;
  }
  post({ type: 'audio', pcm, sampleRate: SAMPLE_RATE, seconds: pcm.length / SAMPLE_RATE, __nonce: message.__nonce }, [pcm.buffer]);
  reply({
    type: 'done',
    steps,
    frames,
    genFrames,
    msTotal: performance.now() - started,
    voiceId: voice.id,
    unknownChars: unknown,
  }, message.__nonce);
}

self.onmessage = async (event) => {
  const message = event.data || {};
  const nonce = message.__nonce;
  try {
    if (message.type === 'init') { await init(message); reply({ type: 'ready', refs: [{ id: 'xiaochun', nameZh: '小莼（纯儿）' }] }, nonce); return; }
    if (message.type === 'synthesize') { await synthesize(message); return; }
  } catch (err) {
    reply({ type: 'error', message: String(err?.message || err) }, nonce);
  }
};