yomichan/ext/js/media/audio-system.js

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/*
* Copyright (C) 2019-2021 Yomichan Authors
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*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
/* global
* TextToSpeechAudio
*/
class AudioSystem extends EventDispatcher {
constructor() {
super();
this._fallbackAudio = null;
}
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prepare() {
// speechSynthesis.getVoices() will not be populated unless some API call is made.
if (
typeof speechSynthesis !== 'undefined' &&
typeof speechSynthesis.addEventListener === 'function'
) {
speechSynthesis.addEventListener('voiceschanged', this._onVoicesChanged.bind(this), false);
}
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}
getFallbackAudio() {
if (this._fallbackAudio === null) {
this._fallbackAudio = new Audio('/data/audio/button.mp3');
}
return this._fallbackAudio;
}
createAudio(url, source) {
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return new Promise((resolve, reject) => {
const audio = new Audio(url);
audio.addEventListener('loadeddata', () => {
if (!this._isAudioValid(audio, source)) {
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reject(new Error('Could not retrieve audio'));
} else {
resolve(audio);
}
});
audio.addEventListener('error', () => reject(audio.error));
});
}
createTextToSpeechAudio(text, voiceUri) {
const voice = this._getTextToSpeechVoiceFromVoiceUri(voiceUri);
if (voice === null) {
throw new Error('Invalid text-to-speech voice');
}
return new TextToSpeechAudio(text, voice);
}
// Private
_onVoicesChanged(e) {
this.trigger('voiceschanged', e);
}
_isAudioValid(audio, source) {
switch (source) {
case 'jpod101':
{
const duration = audio.duration;
return (
duration !== 5.694694 && // Invalid audio (Chrome)
duration !== 5.720718 // Invalid audio (Firefox)
);
}
default:
return true;
}
}
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_getTextToSpeechVoiceFromVoiceUri(voiceUri) {
try {
for (const voice of speechSynthesis.getVoices()) {
if (voice.voiceURI === voiceUri) {
return voice;
}
}
} catch (e) {
// NOP
}
return null;
}
}