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

1. sherpa-onnx runtime installed
2. Piper voice models downloaded
3. 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

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 bubble
• MEDIA:path - Path to the generated OGG Opus audio file

Available Voices

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