Skip to main content

Text to Speech

Generate natural-sounding speech from text, ready to save as a WAV file or play back in your app.

import 'dart:io';
import 'package:nobodywho/nobodywho.dart' as nobodywho;

// ... after NobodyWho.init().
final tts = await nobodywho.TextToSpeech.load(
  source: 'hf://NobodyWho/Kokoro-82M', // Hugging Face repo (hf://owner/repo) or local folder with the model files.
  voice: 'bf_emma', // Voice to use from the model.
  language: 'en-gb', // Language code for the input text.
);

// Generate WAV bytes for this sentence.
final wav = await tts.synthesize(text: 'Hello from NobodyWho!');
// Save the audio to a file.
await File('out.wav').writeAsBytes(wav);

Models and sources​

NobodyWho supports three speech synthesis architectures, all in ONNX format:

source can be a Hugging Face repo (hf://owner/repo) as shown above, or a local directory laid out the same way as that repo. See Local model folder format and Architecture for setup details.

Kokoro​

For Kokoro, set voice and language together. They must agree with the model's available voices.

// ... after NobodyWho.init().
final tts = await nobodywho.TextToSpeech.load(
  source: 'hf://NobodyWho/Kokoro-82M',
  voice: 'bf_emma',
  language: 'en-gb',
);

Optional settings include:

  • voice: voice to use from the model, e.g. bf_emma. See the Kokoro voices folder for the full list. Defaults to bf_emma.
  • language: input language code. Supported values are listed on the Kokoro model page. Defaults to en-gb.
  • speed: speech speed multiplier. 1.0 is normal speed, lower values are slower, higher values are faster. Defaults to 1.0.

Supertonic​

For Supertonic, you can start with the default voice and language, or set them explicitly.

// ... after NobodyWho.init().
final tts = await nobodywho.TextToSpeech.load(
  source: 'hf://Supertone/supertonic-3',
  language: 'en',
);

Optional settings include:

  • voice: voice style. Supported values are M1 to M5 and F1 to F5. Defaults to M1.
  • language: input language code. See the Supertonic model page for the full list. Defaults to en.
  • speed: speech speed multiplier. 1.0 is normal speed, lower values are slower, higher values are faster. Defaults to 1.05.
  • steps: denoising steps. Higher values can improve quality but are slower. Lower values are faster but can sound rougher. Must be greater than 0; defaults to 8.
  • silenceDuration: seconds of silence between long text chunks. Higher values add longer pauses. Must be 0 or higher; defaults to 0.3.

Pocket TTS​

For Pocket TTS, start with the default voice and language, or set them explicitly.

final tts = await nobodywho.TextToSpeech.load(
  source: 'hf://KevinAHM/pocket-tts-onnx',
  voice: 'alba',
  language: 'english_2026-04',
  huggingfaceToken: 'hf_...', // Alternative: set the HF_TOKEN environment variable.
);

Optional settings include:

  • voice: built-in voice name. See the Pocket TTS voice catalogue. Defaults to alba.
  • language: language bundle name. See the available language bundles. Defaults to english_2026-04.
  • steps: quality steps. Higher values are slower. Defaults to 1.
  • precision: int8 for faster loading or fp32 for higher quality. Defaults to int8.
  • temperature: controls how varied the speech sounds. Defaults to 0.7.

Pocket TTS voice states are gated in kyutai/pocket-tts. Accept its terms, then pass a Hugging Face access token with huggingfaceToken, or alternatively set the HF_TOKEN environment variable.

Architecture​

architecture is the TextToSpeech model family behind a source. In most cases, you do not need to set it because NobodyWho can infer it by looking for "kokoro", "pocket-tts", or "supertonic" in the source string.

Set architecture when you use a local directory or a custom source that NobodyWho cannot recognize:

// ... after NobodyWho.init().
final tts = await nobodywho.TextToSpeech.load(
  source: '/path/to/local/kokoro-folder',
  architecture: .kokoro',
);

Supported architecture values are kokoro, pocket-tts, and supertonic.

GPU​

TextToSpeech uses GPU acceleration by default when available. Disable it with useGpu: false:

// ... after NobodyWho.init().
final tts = await nobodywho.TextToSpeech.load(
  source: 'hf://Supertone/supertonic-3',
  useGpu: false,
);

Local model folder format​

When source is a local directory, point it at the top-level model folder and pass the matching architecture.

Use the Hugging Face file browsers as the reference layouts:

For Supertonic, that top-level folder must include both the onnx/ and voice_styles/ directories. Download the model files with the same relative paths, then pass that folder as source.