Friday, April 8, 2022

[SOLVED] speechSynthesis.getVoices() is empty array in Chromium Fedora

Issue

Is Speech Synthesis API supported by Chromium? Do I need to install voices? If so how can I do that? I'm using Fedora. Is voices like video that I need to install extra package for it to work?

I've tried this code:

var msg = new SpeechSynthesisUtterance('I see dead people!');
msg.voice = speechSynthesis.getVoices().filter(function(voice) {
    return voice.name == 'Whisper';
})[0];
speechSynthesis.speak(msg);

from article Web apps that talk - Introduction to the Speech Synthesis API

but the function speechSynthesis.getVoices() return empty array.

I've also tried:

window.speechSynthesis.onvoiceschanged = function() {
    console.log(window.speechSynthesis.getVoices())
};

the function get executed but the array is also empty.

On https://fedoraproject.org/wiki/Chromium there is info to use --enable-speech-dispatcher flag but when I've use it I've got warning that flag is not supported.


Solution

Is Speech Synthesis API supported by Chromium?

Yes, the Web Speech API has basic support at Chromium browser, though there are several issues with both Chromium and Firefox implementation of the specification, see see Blink>Speech, Internals>SpeechSynthesis, Web Speech.

Do I need to install voices? If so how can I do that? I'm using Fedora. Is voices like video that I need to install extra package for it to work?

Yes, voices need to be installed. Chromium is not shipped with voices to set at SpeechSynthesisUtterance voice attribute by default, see How to use Web Speech API at chromium?; How to capture generated audio from window.speechSynthesis.speak() call?.

You can install speech-dispatcher as a server for the system speech synthesis server and espeak as the speech synthesizer. 

$ yum install speech-dispatcher espeak

You can also set a configuration file for speech-dispatcher in the user home folder to set specific options for both speech-dispatcher and the output module that your use, for example espeak

$ spd-conf -u

Launching Chromium with --enable-speech-dispatcher flag automatically spawns a connection to speech-dispatcher, where you can set the LogLevel between 0 and 5 to review SSIP communication between Chromium code and speech-dispatcher.

.getVoices() returns results asynchronously and needs to be called twice

see this electron issue at GitHub Speech Synthesis: No Voices #586.

window.speechSynthesis.onvoiceschanged = e => {
  const voices = window.speechSynthesis.getVoices();
  // do speech synthesis stuff
  console.log(voices);
}
window.speechSynthesis.getVoices();

or composed as an asynchronous function which returns a Promise with value being array of voices

(async() => {

  const getVoices = (voiceName = "") => {
    return new Promise(resolve => {
      window.speechSynthesis.onvoiceschanged = e => {
        // optionally filter returned voice by `voiceName`
        // resolve(
        //  window.speechSynthesis.getVoices()
        //  .filter(({name}) => /^en.+whisper/.test(name))
        // );
        resolve(window.speechSynthesis.getVoices());
      }
      window.speechSynthesis.getVoices();
    })
  }

  const voices = await getVoices();
  console.log(voices);

})();


Answered By - guest271314
Answer Checked By - David Marino (WPSolving Volunteer)
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