modbender Voice Reply
Generate voice audio replies using local Piper TTS via sherpa-onnx. Completely offline, no cloud APIs needed.
Features
- 100% Local - No internet connection required after setup
- No API Keys - Free to use, no accounts needed
- Multi-language - German and English voices included
- Telegram Ready - Outputs voice notes that display as bubbles
- Auto-detect Language - Automatically selects voice based on text
Prerequisites
- sherpa-onnx runtime installed
- Piper voice models downloaded
- ffmpeg for audio conversion
Installation
Quick Install
cd scripts
sudo ./install.sh
Manual Installation
1. Install sherpa-onnx
sudo mkdir -p /opt/sherpa-onnx
cd /opt/sherpa-onnx
curl -L -o sherpa.tar.bz2 "https://github.com/k2-fsa/sherpa-onnx/releases/download/v1.12.23/sherpa-onnx-v1.12.23-linux-x64-shared.tar.bz2"
sudo tar -xjf sherpa.tar.bz2 --strip-components=1
rm sherpa.tar.bz2
2. Download Voice Models
sudo mkdir -p /opt/piper-voices
cd /opt/piper-voices
# German - thorsten (medium quality, natural male voice)
curl -L -o thorsten.tar.bz2 "https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-piper-de_DE-thorsten-medium.tar.bz2"
sudo tar -xjf thorsten.tar.bz2 && rm thorsten.tar.bz2
# English - ryan (high quality, clear US male voice)
curl -L -o ryan.tar.bz2 "https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-piper-en_US-ryan-high.tar.bz2"
sudo tar -xjf ryan.tar.bz2 && rm ryan.tar.bz2
3. Install ffmpeg
sudo apt install -y ffmpeg
4. Set Environment Variables
Add to your OpenClaw service or shell:
export SHERPA_ONNX_DIR="/opt/sherpa-onnx"
export PIPER_VOICES_DIR="/opt/piper-voices"
Usage
{baseDir}/bin/voice-reply "Text to speak" [language]
Parameters
| Parameter | Description | Default |
|---|---|---|
| text | The text to convert to speech | (required) |
| language | de for German, en for English |
auto-detect |
Examples
# German (explicit)
{baseDir}/bin/voice-reply "Hallo, ich bin dein Assistent!" de
# English (explicit)
{baseDir}/bin/voice-reply "Hello, I am your assistant!" en
# Auto-detect (detects German from umlauts and common words)
{baseDir}/bin/voice-reply "Guten Tag, wie geht es dir?"
# Auto-detect (defaults to English)
{baseDir}/bin/voice-reply "The weather is nice today."
Output Format
The script outputs two lines that OpenClaw processes for Telegram:
[[audio_as_voice]]
MEDIA:/tmp/voice-reply-output.ogg
[[audio_as_voice]]- Tag that tells Telegram to display as voice bubbleMEDIA:path- Path to the generated OGG Opus audio file
Available Voices
| Language | Voice | Quality | Description |
|---|---|---|---|
| German (de) | thorsten | medium | Natural male voice, clear pronunciation |
| English (en) | ryan | high | Clear US male voice, professional tone |
Adding More Voices
Browse available Piper voices at:
- https://rhasspy.github.io/piper-samples/
- https://github.com/k2-fsa/sherpa-onnx/releases/tag/tts-models
Download and extract to $PIPER_VOICES_DIR, then modify the script to include the new voice.
Troubleshooting
"TTS binary not found"
Ensure SHERPA_ONNX_DIR is set and contains bin/sherpa-onnx-offline-tts.
"Failed to generate audio"
Check that voice model files exist: *.onnx, tokens.txt, espeak-ng-data/
Audio plays as file instead of voice bubble
Ensure the output includes [[audio_as_voice]] tag on its own line before the MEDIA: line.
Credits
- sherpa-onnx - Offline speech processing
- Piper - Fast local TTS voices
- Thorsten Voice - German voice dataset