---
license: apache-2.0
language:
- de
pipeline_tag: text-to-speech
library_name: sherpa-onnx
base_model: Godelaune/Kokoro-82M-ONNX-German-Martin
tags:
- onnx
- kokoro
- sherpa-onnx
- text-to-speech
- german
- single-speaker
---

# Kokoro German "Martin" — sherpa-onnx package

The German Kokoro voice **Martin**, repackaged so it loads and runs in
**[sherpa-onnx](https://github.com/k2-fsa/sherpa-onnx)** for fully offline, on-device German
text-to-speech.

This is a **repackaging, not a retraining** — the weights are untouched. The only changes are the
metadata and file layout sherpa-onnx needs in order to load a Kokoro model at all.

## Why the repackaging is needed

sherpa-onnx's Kokoro TTS reads its configuration out of the ONNX file's **metadata** (model type,
sample rate, speaker table, style dimensions, …) to know how to run the model, and it expects the
speaker style vectors as a single flat **`voices.bin`**. The upstream Martin export provides
neither — the ONNX carries no sherpa-onnx metadata, and the voice ships as a NumPy `.npz` — so
sherpa-onnx cannot load it directly. This package fixes exactly that:

- **injects the sherpa-onnx Kokoro metadata** into the ONNX (`model_type=kokoro`,
  `sample_rate=24000`, `style_dim=510,1,256`, `n_speakers=1`, `id2speaker=0->martin`, …), copied
  from k2-fsa's own Kokoro release schema, and
- **converts** the voice `.npz` (one `(510,1,256)` float32 array) into the flat little-endian
  `voices.bin` sherpa expects (522 240 bytes).

The result loads and synthesizes in sherpa-onnx with the weights unchanged.

## What's in the archive

`kokoro-de-martin.tar.bz2`:

- `model.onnx` — the Martin ONNX with sherpa-onnx Kokoro metadata injected
- `voices.bin` — the voice style vector (510×1×256 float32)
- `tokens.txt` — from the k2-fsa sherpa-onnx Kokoro release
- `espeak-ng-data/` — from **espeak-ng 1.52** (see the pronunciation note below)

## Pronunciation notes (German G2P)

sherpa-onnx phonemizes German with espeak-ng / piper-phonemize, and two properties of that
pipeline affect raw-text rendering. Both are properties of the sherpa-onnx Kokoro G2P, not of the
voice weights.

- **`ʊɐ` ("ur") vowel — fixed in this package.** The espeak-ng-data shipped by k2-fsa's base
  Kokoro release is stale and emits a literal `?` for the vocalized-r `ʊɐ`, so `durch`, `kurz`,
  `wurde`, … mispronounce. This package instead bundles current **espeak-ng 1.52** data, which
  resolves `ʊɐ` correctly (`durch` → `dˈʊɐç`). A build-time check guards it.
- **ich-laut `/ç/` — needs a phonemizer patch, not a lexicon.** piper-phonemize NFD-decomposes
  `ç` into `c` + combining cedilla (U+0327), which the precomposed Kokoro token set drops, so
  `ich`, `nicht`, `-lich` / `-ig` don't render cleanly. **Note the usual "add a lexicon entry"
  workaround does _not_ apply here:** sherpa-onnx consults the Kokoro lexicon only for its
  dictionary languages (en/zh); for espeak-driven languages (incl. German) it goes straight to
  espeak and never reads the lexicon. The fix has to be in the phonemizer — recompose the pair
  back to `ç` when that codepoint is a known token. The [Page Reader](https://github.com/) app
  that consumes this package carries exactly that patch in its bundled sherpa-onnx build; if you
  run this archive on **stock** sherpa-onnx, ç-words are still affected.

## How it was built

Reproducibly, by a small build chain: fetch the upstream Martin ONNX + voice `.npz` and k2-fsa's
base Kokoro release (for the metadata schema, `tokens.txt`, and `espeak-ng-data/`), inject the
metadata, convert the `.npz` to `voices.bin`, and assemble the archive. A verify step then loads
the result in sherpa-onnx and synthesizes a German clip to confirm it works before publishing.

## Provenance & license

**Apache-2.0**, inherited from upstream. The weights are unchanged from the source fine-tune:

- ONNX source: [Godelaune/Kokoro-82M-ONNX-German-Martin](https://huggingface.co/Godelaune/Kokoro-82M-ONNX-German-Martin)
- Fine-tune: [kikiri-tts/kikiri-german-martin](https://huggingface.co/kikiri-tts/kikiri-german-martin)
  (Martin Harbecke voice, StyleTTS2)
- Architecture: [hexgrad/Kokoro-82M](https://huggingface.co/hexgrad/Kokoro-82M)
- `tokens.txt` + `espeak-ng-data/`: k2-fsa sherpa-onnx Kokoro release

## Usage

Extract `kokoro-de-martin.tar.bz2` and point sherpa-onnx's Kokoro config at `model.onnx`,
`voices.bin`, `tokens.txt`, and `espeak-ng-data/` with `lang=de`.