| --- |
| license: cc0-1.0 |
| language: |
| - de |
| pipeline_tag: text-to-speech |
| library_name: piper |
| tags: |
| - piper |
| - tts |
| - onnx |
| - vits |
| - thorsten-voice |
| - german |
| --- |
| |
| # Thorsten-Voice – Piper (German, trained from scratch, v0.1 experimental) |
|
|
| A German single-speaker [Piper](https://github.com/OHF-Voice/piper1-gpl) voice by |
| [Thorsten-Voice](https://www.thorsten-voice.de), **trained entirely from scratch on Thorsten's own |
| CC0 recordings**. |
|
|
| Most Piper voices are fine-tuned from the `en_US-lessac` checkpoint, whose underlying dataset is |
| licensed for research use only. This model uses **no third-party checkpoint at all** – no |
| `--ckpt_path`, no `--model.warmstart_ckpt`, no `--model.vocoder_warmstart_ckpt`. The weights are |
| derived exclusively from the CC0 dataset below and are released under **CC0 1.0**. |
|
|
| > **Status: experimental (v0.1).** Clearly intelligible and recognisably Thorsten's voice, but |
| > pronunciation and stress of some words are noticeably weaker than in the existing |
| > lessac-based Thorsten Piper voice (see *Limitations*). Published mainly as a clean, |
| > license-unencumbered base checkpoint. |
|
|
| ## Files |
|
|
| | File | Description | |
| |---|---| |
| | `de_DE-thorsten_scratch-medium.onnx` | Voice model (epoch 1799, end of LR schedule) | |
| | `de_DE-thorsten_scratch-medium.onnx.json` | Voice config | |
| | `checkpoints/epoch=1799-last.ckpt` | Full Lightning checkpoint (generator + discriminators + optimizer) for fine-tuning | |
| | `checkpoints/epoch=1791-val_mos=3.3306.ckpt` | Checkpoint with best UTMOS score | |
|
|
| ## Usage |
|
|
| ```sh |
| pip install piper-tts |
| echo "Hallo, ich bin die Stimme von Thorsten." | \ |
| piper -m de_DE-thorsten_scratch-medium.onnx -f hallo.wav |
| ``` |
|
|
| ### Fine-tuning on top of this checkpoint |
|
|
| Use it as a lessac-free starting point (any espeak-ng language, `medium` quality): |
|
|
| ```sh |
| python3 -m piper.train fit ... --model.warmstart_ckpt checkpoints/epoch=1799-last.ckpt |
| ``` |
|
|
| ## Training data |
|
|
| - Dataset: **Thorsten-Voice 2022.10** (neutral), CC0 |
| - 12,450 utterances, 11.22 h, 22,050 Hz, mono, mean utterance length 3.24 s |
| - Text: lower-cased, normalized; phonemized with espeak-ng (`de`) |
| - Split: 10 % validation (`validation_split 0.1`), 20 test examples – these were **not** used for training |
|
|
| ## Training setup |
|
|
| | | | |
| |---|---| |
| | Code | piper1-gpl, commit `<COMMIT>` (version `<VERSION>`) | |
| | Framework | PyTorch 2.15.0+cu132, Lightning | |
| | Hardware | 1 × NVIDIA A40 (48 GB) | |
| | Duration | ~4.3 days (Nov 4–9, 2026) | |
| | Epochs | 1,800 (~214 vocoder passes over the training audio) | |
| | Batch size | 32, length bucketing enabled | |
| | Quality | medium, 22,050 Hz | |
| | LR schedule | exponential decay to 5 % of initial LR, derived from `max_epochs` | |
|
|
| ### Final validation metrics |
|
|
| | Checkpoint | val_mel | val_mos (UTMOS) | |
| |---|---|---| |
| | epoch 1799 (`last`) | 0.3751 | – | |
| | epoch 1791 | – | 3.33 | |
|
|
| UTMOS is trained mainly on English; German voices typically land between 3.3 and 3.8. |
|
|
| ## Limitations |
|
|
| - **Pronunciation/stress:** compared with the lessac-based Thorsten Piper voice, some words are |
| stressed or pronounced less accurately (e.g. *Intendantin, Rathaus, sprichst, Tobias, |
| Rheinufer, Gratiszeitungen*). Likely causes: only ~10 h of training audio without any |
| pretraining, combined with espeak-ng phonemization errors for these words that a model with |
| more data compensates for better. |
| - Single speaker, neutral style only. |
|
|
| ## Export note |
|
|
| With PyTorch ≥ 2.9 the ONNX export in piper1-gpl needed two adjustments: |
| `pip install onnxscript`, and `dynamo=False` in the `torch.onnx.export(...)` call of |
| `src/piper/train/export_onnx.py` (the new exporter fails on the VITS spline flows). |
|
|
| ## License |
|
|
| Model weights and this card: **CC0 1.0** (public domain dedication). |
| The Piper training/runtime code (piper1-gpl) and espeak-ng are GPL-3.0; this affects the software, |
| not the voice model. |
|
|
| ## Credits |
|
|
| Voice and dataset: Thorsten Müller / [Thorsten-Voice](https://www.thorsten-voice.de). |
| Training framework: [Piper](https://github.com/OHF-Voice/piper1-gpl) by Michael Hansen and contributors. |
|
|
