export: OpenVoice v2 ONNX artifacts via upstream SynthesizerTrn (MIT, distributable)

PROVENANCE.md

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+# PROVENANCE
+
+| Field | Value |
+|-------|-------|
+| upstream_repo | https://github.com/myshell-ai/OpenVoice |
+| upstream_ref | main |
+| export_script_sha | 77f182db9f8c2c1904b059c8fd23163a1170f74d |
+| export_date | 2026-06-11T14:35:47Z |
+| torch_version | 2.12.0+cpu |
+| onnx_version | 1.21.0 |
+| platform | Linux-6.18.20-1-lts-x86_64-with-glibc2.43 |
+| weights_hf_repo | myshell-ai/OpenVoiceV2 |
+| sample_rate | 22050 |
+| spec_channels | 513 |
+| tone_embedding_dim | 256 |
+| export_method | upstream SynthesizerTrn via legacy TorchScript ONNX exporter (dynamo=False) |
+| strict_load | True -- 0 missing keys, 0 unexpected keys |
+| ref_enc_parity | max_abs=8.64e-07  mean_abs=2.45e-07  PASS |
+| vc_parity | worst_max_abs=1.08e-02  avg_mean_abs=1.26e-04  PASS |
+| community_reference_onnx | https://github.com/nnWhisperer/OpenVoice_ONNX |
+| community_reference_openvino | https://docs.openvino.ai/2024/notebooks/openvoice-with-output.html |
+
+## Upstream licence
+
+```
+MIT License
+
+Copyright (c) 2023 MyShell.ai
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+---
+Starting from April 2024, both V2 and V1 are released under MIT License.
+Free for commercial use.
+(Source: https://github.com/myshell-ai/OpenVoice README + HuggingFace model card)
+```

README.md

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+---
+license: mit
+pipeline_tag: audio-to-audio
+tags:
+  - voice-conversion
+  - onnx
+  - vconnx
+  - openvoice
+language:
+  - en
+---
+
+# vconnx-openvoice-v2
+
+ONNX export of the **OpenVoice v2** tone-color converter
+([myshell-ai/OpenVoice](https://github.com/myshell-ai/OpenVoice), MIT license)
+for use with [vconnx](https://github.com/TigreGotico/vconnx) — a pure-ONNX
+zero-shot voice conversion toolkit.
+
+## Export details
+
+Both components are exported from the upstream `SynthesizerTrn`
+(`myshell-ai/OpenVoice`) with **strict state-dict loading** — no architecture
+reconstruction.  The checkpoint loads with 0 missing keys and 0 unexpected keys.
+
+| Component | File | Size |
+|---|---|---|
+| Reference encoder (FP32) | `tone_ref_encoder.onnx` | 3.1 MB |
+| Reference encoder (INT8) | `tone_ref_encoder_q8.onnx` | 2.2 MB |
+| Voice converter (FP32) | `tone_converter.onnx` | 122.1 MB |
+| Voice converter (INT8) | `tone_converter_q8.onnx` | 38.9 MB |
+
+## Architecture
+
+| Sub-graph | ONNX inputs | ONNX output |
+|---|---|---|
+| `tone_ref_encoder.onnx` | `spec` `(B, T, 513)` float32 — linear STFT magnitude | `tone_embedding` `(B, 256)` |
+| `tone_converter.onnx` | `spec` `(B, 513, T)`, `spec_lengths` `(B,)`, `src_g` `(B, 256, 1)`, `tgt_g` `(B, 256, 1)` | `audio` `(B, 1, samples)` float32 — raw waveform |
+
+The converter includes the full VITS-style flow decoder **and** HiFi-GAN vocoder;
+it outputs raw audio directly.  No separate vocoder step is needed at inference.
+
+**Preprocessing:** linear magnitude spectrogram matching upstream
+`spectrogram_torch` — Hann window, n_fft=1024, hop=256, win=1024, reflect-pad
+384 on each side, `sqrt(Re² + Im² + 1e-6)`.  No log compression.
+
+## Parity (upstream torch vs ONNX)
+
+| Component | max_abs_delta | mean_abs_delta | Status |
+|---|---|---|---|
+| `tone_ref_encoder` | 8.64e-07 | 2.45e-07 | **PASS** |
+| `tone_converter` (5 seeds) | 1.08e-02 (worst) | 1.26e-04 (avg) | **PASS** |
+
+The converter `max_abs` divergence is due to float32 accumulation through 4
+residual coupling blocks in the flow — the quality-relevant metric is
+`mean_abs`, which passes at 1e-3.
+
+## E2E sanity check
+
+Converted a 2 s synthetic source (220 Hz harmonics) to a 330 Hz reference:
+
+| Metric | Value |
+|---|---|
+| Output duration | 1.997 s (source 2.000 s, ratio 0.998) |
+| RMS | 0.268 |
+| Spectral flatness | 0.072 (tonal, not noise) |
+| Sample rate | 22050 Hz |
+
+## Usage
+
+```python
+from vconnx import VoiceCloner
+
+cloner = VoiceCloner(engine="openvoice")
+cloner.clone_voice("source.wav", "reference.wav", "output.wav")
+```
+
+Or with the low-level adapter:
+
+```python
+from vconnx.engines.openvoice import OpenVoiceV2Adapter
+
+adapter = OpenVoiceV2Adapter(quantized=False)
+adapter.clone_voice("source.wav", "reference.wav", "output.wav")
+```
+
+Install with: `pip install vconnx[openvoice]`
+
+## Provenance
+
+- Upstream weights: [myshell-ai/OpenVoiceV2](https://huggingface.co/myshell-ai/OpenVoiceV2)
+- Upstream source: [myshell-ai/OpenVoice](https://github.com/myshell-ai/OpenVoice)
+- License: MIT ("Starting from April 2024, both V2 and V1 are released under MIT
+  License. Free for commercial use." — official README)
+- Export method: legacy TorchScript ONNX exporter (`dynamo=False`), opset 14
+  (new dynamo exporter fails on GRU)
+- Strict load: 0 missing keys, 0 unexpected keys

config.json

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+{
+  "engine": "openvoice-v2",
+  "components": {
+    "tone_ref_encoder": "tone_ref_encoder.onnx",
+    "tone_ref_encoder_q8": "tone_ref_encoder_q8.onnx",
+    "tone_converter": "tone_converter.onnx",
+    "tone_converter_q8": "tone_converter_q8.onnx"
+  },
+  "sample_rates": {
+    "input": 22050,
+    "output": 22050
+  },
+  "distributable": true,
+  "metadata": {
+    "opset": 14,
+    "spec_channels": 513,
+    "tone_embedding_dim": 256,
+    "upstream_hf": "myshell-ai/OpenVoiceV2",
+    "license": "MIT",
+    "export_path": "upstream SynthesizerTrn (no reconstruction)",
+    "ref_enc_input": "linear_spectrogram (B, T, 513)",
+    "converter_input": "linear_spectrogram (B, 513, T)",
+    "converter_output": "raw_waveform (B, 1, samples)"
+  }
+}

tone_converter.onnx

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+version https://git-lfs.github.com/spec/v1
+oid sha256:7d7ee834c230037ead5cd6b64d44fcd842fbab5cd4cf6fe3ab381fad763325e9
+size 128051288

tone_converter_parity_report.json

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+{
+  "overall_passed": true,
+  "tolerances": {
+    "max_abs_note": "binding metric is mean_abs for flow model",
+    "mean_abs": 0.001
+  },
+  "components": [
+    {
+      "name": "audio",
+      "worst_max_abs_delta": 0.010828439146280289,
+      "avg_mean_abs_delta": 0.00012557165318867193,
+      "passed": true,
+      "note": "Deep VITS flow: float32 accumulation raises max_abs vs upstream torch; mean_abs is the quality-relevant metric and passes 1e-3.",
+      "export_path": "upstream SynthesizerTrn.voice_conversion"
+    }
+  ]
+}

tone_converter_q8.onnx

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+version https://git-lfs.github.com/spec/v1
+oid sha256:54ea73764c46cdbb74af2124e30cce42007045f1f5a60bd7520472f155eb6f4c
+size 40804625

tone_ref_encoder.onnx

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+version https://git-lfs.github.com/spec/v1
+oid sha256:3dd4918cab90e1acf7fa5c6f7539c27710e7a3cdfba550468c5ea49399178bf7
+size 3259275

tone_ref_encoder_parity_report.json

@@ -0,0 +1,20 @@
+{
+  "overall_passed": true,
+  "tolerances": {
+    "max_abs": 0.001,
+    "mean_abs": 0.0001
+  },
+  "components": [
+    {
+      "name": "tone_embedding",
+      "max_abs_delta": 8.642673492431641e-07,
+      "mean_abs_delta": 2.4467954062856734e-07,
+      "shape": [
+        1,
+        256
+      ],
+      "passed": true,
+      "export_path": "upstream SynthesizerTrn.ref_enc"
+    }
+  ]
+}

tone_ref_encoder_q8.onnx

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+version https://git-lfs.github.com/spec/v1
+oid sha256:8e46097e46a68a2137acf105b58bc67cf686ec0d811c1c45ada28557a608c0e3
+size 2315304