Reza2kn/Higgs-Audio-v3-TTS-4bit-ONNX

Higgs Audio v3 TTS 4-bit ONNX Vocoder

This repository contains an ONNX export of the Higgs Audio v3 bundled codec decoder/vocoder:

audio_codes [B, 8, T] int64 -> audio_values [B, 1, samples] float32

It is a browser-deployment component for Higgs Audio TTS, not the complete text-to-speech pipeline. The autoregressive Qwen3 text-to-codebook generator is still a separate custom SGLang graph and is not included here.

Files

• higgs_audio_v3_vocoder_decode.onnx + .onnx.data: fp32 ONNX vocoder.
• higgs_audio_v3_vocoder_decode_matmul4.onnx + .onnx.data: ONNX Runtime weight-only 4-bit quantization for supported MatMul and Gather nodes.
• vocoder_onnx_export_report.json: PyTorch vs ONNX Runtime validation.
• vocoder_onnx_matmul4_report.json: 4-bit ONNX Runtime validation.

Validation

The fp32 vocoder export passed ONNX checker and ONNX Runtime CPU inference:

• max absolute diff vs PyTorch: 0.0007368475
• mean absolute diff vs PyTorch: 0.0000280040
• mean relative diff vs PyTorch: 0.0053399284

The 4-bit ONNX Runtime artifact replaced:

• Gather: 8 -> GatherBlockQuantized: 8
• MatMul: 9 -> MatMulNBits: 9

and passed ONNX Runtime CPU inference against the fp32 ONNX graph.

Limitation

This is not a full in-browser TTS model yet. A complete browser version still needs the autoregressive Higgs/Qwen3 text-to-codebook generator exported to an ONNX Runtime Web compatible graph and a JavaScript sampling loop for the 8-codebook delayed-token generation.