Clone a voice with Chatterbox TTS

Now that we can synthesize English speech with Supertonic, we're going to add voice cloning. Chatterbox takes a reference audio file and synthesizes speech in that voice.

Chatterbox is a two-file engine. A T3 GGUF handles the language side; an S3Gen GGUF handles the audio decoder. Both are available as registry constants. Load them together by setting ttsEngine: "chatterbox" and passing s3genModelSrc alongside the top-level modelSrc.

Chatterbox is a two-stage TTS setup: T3 (language → acoustic tokens), S3Gen (tokens → waveform). One loadModel() brings both, with modelConfig wiring the second stage. The split load would look like the following:

const modelId = await loadModel({
  modelSrc: TTS_T3_TURBO_EN_CHATTERBOX_Q8_0,
  modelConfig: {
    ttsEngine: "chatterbox",
    language: "en",
    s3genModelSrc: TTS_S3GEN_EN_CHATTERBOX.src,
    streamChunkTokens: 25,
    streamFirstChunkTokens: 10,
    cfmSteps: 1,
  },
});

Voice cloning is opt-in via referenceAudioSrc. Pass a path to a 16-bit mono WAV of the target speaker, and Chatterbox conditions the decoder on it. Without referenceAudioSrc, Chatterbox uses its bundled default voice. The reference clip should be a clean, single-speaker sample of 5 to 30 seconds.

textToSpeech() is fire-and-await. The call returns a 24 kHz mono Int16Array. Synthesizing speech in the default voice looks like this:

const result = textToSpeech({
  modelId,
  text: "Hello, world.",
  inputType: "text",
  stream: false,
});
const audioBuffer = await result.buffer;
console.log(`▸ TTS complete. Total samples: ${audioBuffer.length}`);

The textToSpeech call matches Supertonic. The only differences are the loadModel modelConfig (Chatterbox needs s3genModelSrc) and the sample rate (24 kHz for Chatterbox, 44.1 kHz for Supertonic).

Note: voice cloning inherits the timbre of the reference, not the words. The synthesized text is whatever you pass to textToSpeech({ text }). The reference only conditions the voice.