---
license: apache-2.0
tags:
- voice-conversion
- speech
- onnx
- audio
---

# TigreGotico/vconnx-facodec

ONNX artifacts for the FACodec (NaturalSpeech 3) voice-conversion engine,
part of [vconnx](https://github.com/TigreGotico/vconnx).

## License

Upstream weights: **Apache-2.0** — [amphion/naturalspeech3_facodec](https://huggingface.co/amphion/naturalspeech3_facodec).  
Code: Amphion (open-mmlab/Amphion) — Apache-2.0.  
ONNX exports: Apache-2.0 (same upstream license, stated here per vconnx publish-all policy).

## Architecture

FACodec (Ju et al., NaturalSpeech 3, ICML 2024) disentangles speech into
content, prosody, timbre, and acoustic detail subspaces.  Voice conversion is
zero-shot: encode source → quantize → swap reference timbre embedding → decode.

| Component | Input → Output | Description |
|---|---|---|
|  | wav(1,1,N) → enc_feats(1,256,T) | Convolutional encoder (hop=200) |
|  | enc_feats(1,256,T) → spk_embs(1,256) | TransformerEncoder timbre extractor |
|  | (enc_feats, mel_20(1,20,T)) → vq_ids(6,1,T) | Factorised VQ — prosody(1)+content(2)+residual(3) |
|  | (vq_ids, spk_embs) → wav(1,1,N) | vq2emb + AdaIN + conv decoder |

## Parity (fp32 torch vs ORT)

| Component | max_abs Δ | mean_abs Δ | Verdict |
|---|---|---|---|
| encoder | 1.62e-05 | 2.36e-06 | PASS |
| timbre | 1.43e-06 | 6.40e-08 | PASS |
| quantize | exact int64 match | — | PASS |
| decoder | 7.50e-09 | 1.46e-09 | PASS |

## Model sizes

| File | Size |
|---|---|
|  (fp32) | 16.5 MB |
|  (INT8) | 4.7 MB |
|  (fp32) | 33.0 MB |
|  (INT8) | 12.1 MB |
|  (fp32) | 33.4 MB |
|  (INT8) | 12.5 MB |
|  (fp32) | 66.2 MB |
|  (INT8) | 36.8 MB |

## Intelligibility (WER gate ≤ 25%)

Tested with edge-tts source (en-US-GuyNeural) converted to two reference voices
(en-US-AriaNeural, en-GB-SoniaNeural) using Whisper base.en transcription.

| Reference voice | WER | Gate |
|---|---|---|
| en-US-AriaNeural | 0% | ✓ PASS |
| en-GB-SoniaNeural | 0% | ✓ PASS |

## References

- https://arxiv.org/abs/2403.03100
- https://huggingface.co/amphion/naturalspeech3_facodec
- https://github.com/TigreGotico/vconnx