mlx-speech

Local speech synthesis, editing, and transcription on Apple Silicon, running pure MLX. No cloud, no PyTorch at runtime.

mlx-speech is an App Automaton project. Project page: appautomaton.renocrypt.com/mlx-speech. The appautomaton org hosts the code on GitHub and the converted weights on Hugging Face.

Models

Published MLX weights live under the App Automaton Hugging Face org, appautomaton, and download automatically when loaded by alias. Flat model repositories load by alias or full repo id — tts.load("fish-s2-pro") and tts.load("appautomaton/fishaudio-s2-pro-8bit-mlx") are equivalent. Shared multi-artifact repositories use an alias or an explicit artifact_subdir so the runtime never guesses a variant. Original checkpoint directories can also be loaded by path when the model-family guide documents their layout. Each model name links to a guide covering behavior, flags, and known limitations.

Text-to-speech

Selector	Model	Weights
fish-s2-pro	Fish S2 Pro — dual-AR TTS, voice cloning, emotion tags	int8
vibevoice	VibeVoice Large — hybrid LLM+diffusion TTS, voice cloning	int8
longcat	LongCat AudioDiT — flow-matching diffusion TTS	int8
moss-local	OpenMOSS TTS Local — local-attention multi-VQ TTS	int8
moss-ttsd	MOSS-TTSD — delay-pattern dialogue TTS	int8
moss-sound-effect	OpenMOSS Sound Effect — text-to-sound-effect generation	4-bit
step-audio	Step-Audio-EditX — voice cloning, audio editing	int8
dramabox	DramaBox — Resemble flow-matching diffusion TTS, 48 kHz stereo	bf16¹
dots-tts-soar	dots.tts SOAR — continuous autoregressive flow-matching TTS and voice cloning	int8 + base
dots-tts-mf	dots.tts MeanFlow — distilled continuous autoregressive TTS and voice cloning	int8 + base

Speech-to-text

Selector	Model	Weights
cohere-asr	Cohere Transcribe — multilingual ASR	int8
qwen3-asr-1.7b	Qwen3-ASR-1.7B — English, Chinese, and mixed Chinese/English ASR	int8 · bf16
nemotron-asr-streaming	NVIDIA Nemotron 3.5 ASR Streaming — cache-aware multilingual streaming across three stated quality tiers	int8
granite-speech-4.0-1b	IBM Granite Speech 4.0 1B — selective-int8 Granite LM with BF16 acoustic encoder and QFormer	int8

¹ tts.load("dramabox") also pulls the Gemma 3 12B backbone text encoder automatically. Output is 48 kHz stereo. For advanced controls (cfg, steps, voice reference) use scripts/generate_dramabox.py. Optional denoise_ref=True cleans a noisy voice reference with the pure-MLX RE-USE / SEMamba enhancer (off by default; NSCLv1 non-commercial weights). See docs/dramabox.md.

Installation

Requires an Apple Silicon Mac (M1 or later) and Python 3.13+.

pip install mlx-speech

Quick Start

Python:

import mlx_speech
from mlx_speech.audio import load_audio, write_wav

# Text-to-speech
model = mlx_speech.tts.load("fish-s2-pro")
result = model.generate("Hello from mlx-speech!")
write_wav("output.wav", result.waveform, sample_rate=result.sample_rate)

# Voice cloning with emotion tags
result = model.generate(
    "[excited] This is amazing!",
    reference_audio="reference.wav",
    reference_text="Transcript of the reference audio.",
)

# Speech-to-text
asr = mlx_speech.asr.load("qwen3-asr-1.7b")
print(asr.generate("audio.wav").text)

# Cache-aware incremental ASR is available on Nemotron
nemotron = mlx_speech.asr.load("nemotron-asr-streaming")
session = nemotron.stream_session(language="en-US", att_context_size=(56, 3))
waveform, _ = load_audio("audio.wav", sample_rate=16_000, mono=True)
for start in range(0, int(waveform.size), 1_600):
    session.feed(waveform[start : start + 1_600])
session.finalize()
print(session.result().text)

# Granite defaults to the published selective-int8 artifact
granite = mlx_speech.asr.load("granite-speech-4.0-1b")
print(granite.generate("audio.wav").text)

# Discover models
mlx_speech.tts.list_models()
mlx_speech.tts.list_models(detailed=True)  # includes shared-repo artifact paths
mlx_speech.asr.list_models()

CLI:

# Generate speech
mlx-speech tts --model fish-s2-pro --text "Hello!" -o output.wav

# Bounded waveform streaming with dots.tts
mlx-speech tts --model dots-tts-soar --text "Hello!" --stream -o streamed.wav

# Voice cloning with emotion tags
mlx-speech tts --model fish-s2-pro \
  --text "[whisper] Just between us..." \
  --reference-audio ref.wav \
  --reference-text "Transcript of reference." \
  -o cloned.wav

# Step Audio emotion editing
mlx-speech tts --model step-audio \
  --reference-audio input.wav \
  --reference-text "Transcript." \
  --edit-type emotion --edit-info happy \
  -o happy.wav

# Sound effect generation
mlx-speech tts --model moss-sound-effect \
  --text "rolling thunder with rainfall" \
  --duration-seconds 8 \
  -o thunder.wav

# Transcribe audio
mlx-speech asr --model cohere-asr --audio speech.wav
mlx-speech asr --model qwen3-asr-1.7b --audio speech.wav --language Chinese
# File transcription with the streaming-capable Nemotron model
mlx-speech asr --model nemotron-asr-streaming --audio speech.wav --language en-US
mlx-speech asr --model granite-speech-4.0-1b --audio speech.wav

# Local checkpoint paths work anywhere an alias does
mlx-speech tts --model models/fish_s2_pro/mlx-int8 --text "Hello!" -o output.wav
mlx-speech asr --model models/ibm/granite_4_0_1b_speech/mlx-int8 --audio speech.wav

# Discover models
mlx-speech tts --list-models
mlx-speech asr --list-models
mlx-speech --help

Note: The mlx-speech CLI covers the common generation, voice cloning, editing, waveform streaming, and transcription paths. For advanced controls (sampling temperature, top-p/k, diffusion steps, batch JSONL, duration tuning, etc.) use the family-specific scripts in scripts/ where provided. Each model guide in docs/ names its canonical advanced entry point and supported controls.

Conversion

Available model-family conversion entry points include:

python scripts/convert/fish_s2_pro.py
python scripts/convert/longcat_audiodit.py
python scripts/convert/vibevoice.py
python scripts/convert/moss_local.py
python scripts/convert/moss_ttsd.py
python scripts/convert/moss_sound_effect.py
python scripts/convert/step_audio_editx.py
python scripts/convert/cohere_asr.py
python scripts/convert/qwen3_asr.py
python scripts/convert/granite_speech_asr.py
python scripts/convert/dots_tts.py --variant all --precision int8
uv run --with torch python scripts/convert/nemotron_asr.py --quant int8

Conversion is an offline workflow and may require source-format-specific tools; those tools are not runtime dependencies. Granite conversion reads the original sharded BF16 safetensors directly and writes a self-contained selective-int8 MLX artifact without PyTorch or mlx-audio.

Development

git clone https://github.com/appautomaton/mlx-speech.git
cd mlx-speech
uv sync
uv run pytest tests/unit/
uv run ruff check .

mlx-speech/
  src/mlx_speech/    library code
  scripts/           conversion, generation, eval, and audit entry points
  models/            local checkpoints (not in git)
  tests/             unit, checkpoint, runtime, integration tests
  docs/              model-family behavior guides

License

MIT — see LICENSE

Built and maintained by App Automaton.

Acknowledgements

This project wouldn't exist without the inspiration and generous support of the incredible community at linux.do.