What is it?

TTS Server is an Android-only application that provides a REST-based interface for on-board TTS engine of your device. The application is aimed on home automation and allows you to give a second life to your old smartphone, which can now act as a standalone, all-inclusive web TTS provider for your speech-based home notification system.

For what?

Android is provided with a great offline TTS engine for almost every language on the world. If you care about high availability of the web TTS provider or you don't want your notifications go through the Internet to the cloud providers, you can utilise your smartphone to done the job.

How does it work?

TTS Server runs a service with HTTP server that exposes endpoints allowing you to perform TTS task. As the Android implements its own process-killer, the application needs to run the service on the foreground (so the notification is always shown) keeping it alive and preventing it from being killed. Because of that, keep in mind that the application might drain your battery, so it is recommended to use it only on the devices being always connected to the power source.

Consuming REST interface

So far, the application provides two endpoints: /say and /wave. Each endpoint works with JSON-based body, so each request requires a proper Content-Type header.

The /say endpoint

POST /say
{
"text": "The text to be spoken",
"language": "en_US"
}

Returns: 200 OK with empty body

The /say endpoint allows you to perform TTS task using device's speakers or the external ones connected to it via jack, Bluetooth etc. For example if you have some old PC-speakers you are able to connect your device to them via line port and get a complete speech-based notification system.

The /wave endpoint

POST /wave
{
"text": "The text to be spoken",
"language": "en_US"
}

Returns: 200 OK with wave file (Content-Type: audio/x-wav)

The /wave endpoint enables you to download a wav file containing speech of the provided text. The goal of this endpoint is to provide interface allowing you establishment of the connection between the TTS Server and some other kind of already running TTS system, which can invoke the HTTP request to your Android device and do something with returned wav file. For example, take a look at my fork of great Node Sonos HTTP API. I've already written a TTS plugin in my fork allowing me to connect the TTS Server and my Sonos speakers right through the Node Sonos HTTP API, which performs the request to the Android device and puts returned wav file on the Sonos speakers.