Skip to main content
Version: 2.2.0

Text to Speech

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

import Foundation
import NobodyWho

let tts = try await Tts.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.
let wav = try await tts.synthesize("Hello from NobodyWho!")
// Save the audio to a file.
try wav.write(to: URL(fileURLWithPath: "out.wav"))

Models and sources​

NobodyWho supports two speech synthesis architectures, both 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.

let tts = try await Tts.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.

let tts = try await Tts.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.

Architecture​

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

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

let tts = try await Tts.load(
    source: "/path/to/local/kokoro-folder",
    architecture: .kokoro
)

Supported architecture values are .kokoro and .supertonic.

GPU​

TTS runs on CPU only on Apple platforms for now. Metal/CoreML acceleration may be added in the future.

Most apps should keep the default device: .auto. If you want to force CPU explicitly, pass device: .cpu:

let tts = try await Tts.load(
    source: "hf://Supertone/supertonic-3",
    device: .cpu
)

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.