speak.js

A port of the eSpeak speech synthesizer from C++ to JavaScript using Emscripten.

Enables text-to-speech on the web using only JavaScript and HTML5.

Note

This is a changed version of speak.js from the commit 9c6f642f7d78bab51d16b2e8b79cdf205643ec35 in Dec 4, 2017.

Usage

Very simple! Do this:

• Include the script in your html header,

<script src="speakClient.js"></script>

(and make sure you have speak_client.js available, as well as speak_worker.js and speak_generator.js)

• Call speak() to say stuff in JavaScript

speak('hello world!', {}, function(data, wav) { ... });

See demo.html for a more detailed example.

Options

You can also specify some options with calling speak(), by doing

speak('hello world', { option1: value1, option2: value2 .. }, function(data, wav) { ... });

available options are:

• amplitude: How loud the voice will be (default: 100)
• pitch: The voice pitch (default: 50)
• speed: The speed at which to talk (words per minute) (default: 175)
• voice: Which voice to use (for a non-default voice, requires you to build speak.js to include the proper data. See Language Support below) (default: en/en-us)
• wordgap: Additional gap between words in 10 ms units (default: 0)
• noWorker: Do not use a web worker (see below in 'Architecture')

For example

speak('hello world', { pitch: 100 }, function(data, wav) { ... });

will talk in a very high-pitched voice.

Architecture

speak_client.js is the file that you interact with. It defines speak(), and will load speak_worker.js in a web worker. speakWorker wraps around speak_generator.js, which does the actual work of converting a string into a WAV file. The WAV data is returned to speak(), which then call the callback parameter returning the WAV file and its metadata.

You can also use speak.js without a web worker. In that case, you don't need speak_worker.js, but you do need to load speak_generator.js along with speak_client.js in your HTML page. speak(), if called with noWorker set to true in the options object, will directly call the WAV generation code in speak_generator.js instead of forwarding the call to a worker which would have done the same.

Building

A prebuilt version is already included. But if you want to tinker with the source code though, you might want to build it yourself. To do so, run emscripten.sh inside src/. Note that you need to change the paths there.

Build dependencies

• emsdk
• sdk-1.37.23-64bit or sdk-1.37.23-32bit

Language Support

eSpeak supports multiple languages so speak.js can too. To do this, you need to build a custom version of speak.js:

• Bundle the proper language files. For french, you need fr_dict and voices/fr. See commented-out code in emscripten.sh and bundle.py
• Run emscripten.sh to build.

You then need to call speak() with the voice option that tells it to use the right voice for your language. For example, for French this should work:

speak('boulanger', { voice: 'fr' }, function(data, wav) { ... });