Runtime weights for c4tts, a standalone C++/MLX inference engine that runs the Confucius4-TTS multilingual, zero-shot, cross-lingual TTS model on Apple Silicon with no Python dependency at run time.

This repository hosts the model converted into c4tts's on-disk format (a directory of .npy tensors that MLX memory-maps, plus the SentencePiece vocab). It is a repackaging of Confucius4-TTS and its component models — see Provenance & licensing. It does not contain new trained weights.

Architecture: speech-encoder + LLM (text→semantic, T2S) → flow-matching diffusion (semantic→mel, S2A) → BigVGAN vocoder (mel→waveform)
Output: 22.05 kHz mono waveform
Languages: 14 (zh, en, ja, ko, de, fr, es, id, it, th, pt, ru, ms, vi)
Capabilities: zero-shot voice cloning from a short reference clip (no transcript needed), cross-lingual voice transfer
Precision: weights shipped as float32; the engine can run the T2S decoder in int8 (quantized_matmul) at run time for ~2× speed at ~0.9999 logit cosine
Footprint: ~4.8 GB (only the tensors the runtime actually loads — e.g. W2V-BERT is trimmed to the layers used for semantic-feature extraction)

Intended use

Local, offline, multilingual TTS and zero-shot voice cloning on macOS / Apple Silicon, via the c4tts engine — e.g. a CLI (c4tts_cli synth) or the built-in HTTP server with an OpenAI-style /v1/audio/speech API and a web console.

Not intended for: real-time deepfakes, impersonation without consent, or any use prohibited by the upstream licenses.

How to use

These are weights for the c4tts engine (a C++/MLX runtime), not a 🤗 Transformers checkpoint — they won't load with AutoModel.

Build the c4tts engine for Apple Silicon (CMake + MLX).
Download this repo into the engine's bin/ directory:
huggingface-cli download <this-repo> --local-dir bin
Layout (8 files): bin/{t2s,s2a,w2vbert,campplus,bigvgan,audio}.safetensors + bin/tokenizer/vocab.tsv. Each module is one memory-mapped safetensors file.
Synthesize (text is tokenized in C++ — no Python at run time):
bash
1# CLI: clone the voice in ref.wav and read the text 2./c4tts_cli synth --prompt ref.wav --lang zh --text "你好，世界。" --out out.wav 3 4# or serve an OpenAI-style API + web console 5./c4tts_cli --web --web-key <key>

Reference audio: a few seconds of clean mono speech is enough for zero-shot cloning; pass --lang to select the synthesis language (cross-lingual transfer is supported).

Model components

Component	Role	Source
`t2s/`	Text→semantic LLM (GPT-2-style, 24 layers) + speaker encoder	Confucius4-TTS `t2s_model.safetensors`
`s2a/`	Semantic→mel flow-matching DiT + WaveNet	Confucius4-TTS `s2a_model.pt`
`tokenizer/vocab.tsv`	LLaMA SentencePiece BPE tokenizer	Confucius4-TTS
`w2vbert/`	W2V-BERT 2.0 semantic-feature encoder (layers used for extraction only)	`facebook/w2v-bert-2.0`
`campplus/`	CAMPPlus speaker embedding	`funasr/campplus` (`campplus_cn_common.bin`)
`bigvgan/`	BigVGAN v2 neural vocoder (22 kHz, 80-band, 256×)	`nvidia/bigvgan_v2_22khz_80band_256x`
`audio/`	Baked mel-filterbank + Hann window constants	derived

Provenance & licensing

This is a derivative / repackaged distribution. You must comply with the license of every upstream component:

Upstream	License	Link
Confucius4-TTS (T2S, S2A, tokenizer)	Apache-2.0	https://huggingface.co/netease-youdao/Confucius4-TTS
W2V-BERT 2.0 (semantic encoder)	MIT	https://huggingface.co/facebook/w2v-bert-2.0
BigVGAN v2 (vocoder)	MIT	https://huggingface.co/nvidia/bigvgan_v2_22khz_80band_256x
CAMPPlus (speaker embedding)	see source	https://huggingface.co/funasr/campplus

The license: apache-2.0 tag reflects the primary model (Confucius4-TTS). Verify the CAMPPlus license for your use case before redistribution.

Limitations & responsible use

Quality varies with reference-audio quality and is best on the 14 supported languages; out-of-distribution text/voices may degrade.
Voice cloning is powerful and easily misused. Only clone voices you have explicit consent to use. Do not use this model to impersonate real people, to deceive, or to generate audio you are not authorized to produce. Consider disclosing AI-generated audio and watermarking outputs.
Synthesis is non-deterministic under sampling; greedy decoding is reproducible.

Citation

Please cite the upstream Confucius4-TTS work:

bibtex

@misc{confucius4tts,
  title  = {Confucius4-TTS: a Multilingual and Cross-Lingual Zero-Shot TTS Engine},
  author = {NetEase Youdao},
  url    = {https://huggingface.co/netease-youdao/Confucius4-TTS}
}

c4tts is an independent C++/MLX runtime; it is not affiliated with or endorsed by NetEase Youdao, Meta, NVIDIA, or FunASR.

raoqu/mlx-c4tts

c4tts weights — Confucius4-TTS for Apple Silicon (C++/MLX)