OpenVoiceOS TTS Server

Lightweight HTTP microservice for any OVOS text‑to‑speech plugin, with optional caching.

Wrap your favorite OVOS TTS engine in a FastAPI service—ready to deploy locally, in Docker, or behind a load balancer.

The OpenVoiceOS TTS HTTP Server exposes any OVOS TTS plugin over a simple HTTP API. Send text, receive audio—no extra glue code required.

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Usage Guide

Install the server

pip install ovos-tts-server

Configure your TTS plugin

In your mycroft.conf (or equivalent) under the tts section:

{
 "tts": {
   "module": "ovos-tts-plugin-xxx",
   "ovos-tts-plugin-xxx": {
     "voice": "xxx"
   }
 }
}

Launch the server

ovos-stt-server \
 --engine ovos-tts-plugin-xxx \
 --host 0.0.0.0 \
 --port 9666

Verify it’s running

Visit http://localhost:9666/status in your browser or run:

curl http://localhost:9666/status

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Command‑Line Options

$ ovos-tts-server --help
usage: ovos-tts-server [-h] [--engine ENGINE] [--port PORT] [--host HOST] [--cache] [--lang LANG] [--gradio] [--title TITLE] [--description DESCRIPTION]
                       [--info INFO] [--badge BADGE]

options:
  -h, --help            show this help message and exit
  --engine ENGINE       tts plugin to be used
  --port PORT           port number
  --host HOST           host
  --cache               save every synth to disk
  --lang LANG           default language supported by plugin
  --gradio              Enable Gradio Web UI
  --title TITLE         Title for webUI
  --description DESCRIPTION
                        Text description to print in UI
  --info INFO           Text to display at end of UI
  --badge BADGE         URL of visitor badge

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Technical Explanation

• FastAPI Core
  Spins up a FastAPI application exposing RESTful endpoints for synthesis and status checks.
• Plugin Loading
  Dynamically loads any OVOS TTS plugin via Python entry points—no code changes needed when adding new voices.
• Caching
  When --cache is enabled, every synthesis request is stored as a WAV file for debugging or reuse.
• Scalability
  Stateless by design—run multiple instances behind NGINX, Traefik, or Kubernetes with round‑robin or load‑based routing.

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HTTP API Endpoints

Endpoint	Method	Description
/status	GET	Returns loaded plugin names and versions.
/synthesize/{utterance}	GET	URL‑encoded text → WAV audio bytes.
/v2/synthesize	GET	JSON {utterance: string, voice?: string} → WAV.
/docs	GET	Interactive OpenAPI (Swagger) docs.

any query parameters passed to /v2/synthesize will be forwarded to the individual plugins get_tts method if they are defined as kwargs there. 💡 This allows "voice" and "lang" to be defined at runtime and not by plugin config at load time (for plugins that support it)

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Companion Plugin

Point your OVOS instance at this TTS server:

pip install ovos-tts-server-plugin

Configuration mycroft.conf:

{
  "tts": {
    "module": "ovos-tts-plugin-server",
    "ovos-tts-plugin-server": {
        "host": "http://localhost:9667",
        "voice": "xxx",
        "verify_ssl": false,
        "tts_timeout": 5
     }
 } 
}

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Docker Deployment

Create a Dockerfile

FROM python:3.7-slim
RUN pip install ovos-tts-server
RUN pip install {YOUR_TTS_PLUGIN}
ENTRYPOINT ["ovos-tts-server", "--engine", "{YOUR_TTS_PLUGIN}"]

Build & Run

docker build -t my-ovos-tts .
docker run -p 8080:9666 my-ovos-tts

Pre-built containers are also available via the ovos-docker-tts repository.

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Tips & Caveats

• Audio Formats: By default, outputs WAV (PCM). If you need MP3 or OGG, wrap with an external converter or check plugin support.
• Disk Usage: Caching every file can grow large; monitor ./cache/ or disable with --no-cache.
• Security: Consider adding API keys or putting a reverse proxy (NGINX, Traefik) in front for SSL termination and rate limiting.
• Plugin Dependencies: Some voices require native libraries (e.g., TensorFlow). Bake them into your Docker image to avoid runtime surprises.

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Links & References

• TTS Server GitHub: https://github.com/OpenVoiceOS/ovos-tts-server
• Companion Plugin: https://github.com/OpenVoiceOS/ovos-tts-server-plugin
• Docker Images: https://github.com/OpenVoiceOS/ovos-docker-tts
• OVOS Plugin Manager: https://github.com/OpenVoiceOS/ovos-plugin-manager