netease-youdao/Confucius4-TTS

Confucius4-TTS: a Multilingual and Cross-Lingual Zero-Shot TTS Engine

What it solves

Confucius4-TTS addresses the challenge of high-quality, multilingual speech synthesis where a single speaker's identity must be preserved across different languages. It specifically solves the problem of "zero-shot" voice cloning, allowing a system to mimic a voice from a short reference clip without needing a transcript of that clip or additional training for new speakers.

How it works

The system uses a "speech encoder + Large Language Model (LLM)" architecture divided into two primary stages:

  1. Text2Semantic (T2S): An autoregressive LLM that generates semantic token sequences based on the input text and speaker conditioning.
  2. Semantic2Acoustic (S2A): A flow-matching model that converts those semantic tokens into mel spectrograms for final audio synthesis.

To optimize performance, it can use a vLLM backend with PagedAttention to accelerate the T2S generation stage. It leverages external components like Wav2Vec2-BERT for semantic feature extraction and BigVGAN as a neural vocoder.

Who it’s for

This tool is designed for developers and researchers working on multilingual applications, content creators needing consistent voice cloning across languages, and anyone building AI-driven speech synthesis systems that require natural, expressive, and unaccented cross-lingual output.

Highlights

  • 14-Language Support: Works across Chinese, English, Japanese, Korean, German, French, Spanish, Indonesian, Italian, Thai, Portuguese, Russian, Malay, and Vietnamese.
  • Transcript-Free Cloning: Clones voices using only a reference audio file, without requiring a written transcript of the reference speech.
  • Cross-Lingual Transfer: Enables a speaker to "speak" a language they don't know while maintaining their unique vocal identity and avoiding unnatural accents.
  • Emotion Transfer: Capable of cloning the emotional tone and feeling of the reference audio, not just the timbre of the voice.
  • Flexible Deployment: Provides a Python API, a Gradio web interface, and a FastAPI server for both streaming and non-streaming audio generation.

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