twilio-video/es5/util/detectsilentaudio.js

Twilio Video JavaScript Library

'use strict';
var detectSilence = require('../webaudio/detectsilence');
var N_ATTEMPTS = 3;
var ATTEMPT_DURATION_MS = 250;
/**
 * Detect whether the audio stream rendered by the given HTMLVideoElement is silent.
 * @param {HTMLAudioElement} el
 * @returns {Promise<boolean>} true if silent, false if not.
 */
function detectSilentAudio(el) {
    // NOTE(mmalavalli): We have to delay require-ing AudioContextFactory, because
    // it exports a default instance whose constructor calls Object.assign.
    var AudioContextFactory = require('../webaudio/audiocontext');
    var holder = {};
    var audioContext = AudioContextFactory.getOrCreate(holder);
    var attemptsLeft = N_ATTEMPTS;
    function doCheckSilence() {
        attemptsLeft--;
        return detectSilence(audioContext, el.srcObject, ATTEMPT_DURATION_MS).then(function (isSilent) {
            if (!isSilent) {
                return false;
            }
            if (attemptsLeft > 0) {
                return doCheckSilence();
            }
            return true;
        }).catch(function () {
            // NOTE(mmalavalli): If an error is thrown while detect silence, the audio
            // stream is assumed to be silent.
            return true;
        });
    }
    // Resolve the returned Promise with true if 3 consecutive attempts
    // to detect silent audio are successful.
    return doCheckSilence().finally(function () {
        AudioContextFactory.release(holder);
    });
}
module.exports = detectSilentAudio;
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