Added ability to switch audio output device

conference.js

         APP.UI.addListener(
             UIEvents.AUDIO_OUTPUT_DEVICE_CHANGED,
             (audioOutputDeviceId) => {
-                APP.settings.setAudioOutputDeviceId(audioOutputDeviceId);
-
-                let promises = [],
-                    track;
-
-                for (let key in room.rtc.remoteTracks) {
-                    track = room.rtc.remoteTracks[key].video;
-
-                    if (track && track.containers.length) {
-                        promises.push(
-                            track.changeAudioOutput(audioOutputDeviceId));
-                    }
-
-                    track = room.rtc.remoteTracks[key].audio;
-
-                    if (track && track.containers.length) {
-                        promises.push(
-                            track.changeAudioOutput(audioOutputDeviceId));
-                    }
-                }
-
-                room.rtc.localTracks.forEach((track) => {
-                    if (track.containers.length) {
-                        promises.push(
-                            track.changeAudioOutput(audioOutputDeviceId));
-                    }
-                });
-
-                Promise.all(promises).then(
-                    () => console.log('audio devices switched'),
-                    (err) => console.error(err));
+                APP.settings.setAudioOutputDeviceId(audioOutputDeviceId)
+                    .then(() => console.log('changed output device'))
+                    .catch((err) => {
+                        console.error('failed to set audio output device', err);
+                    });
             }
         );
 

lang/main.json

         "startVideoMuted": "Start without video",
         "selectCamera": "Select camera",
         "selectMic": "Select microphone",
+        "selectAudioOutput": "Select audio output",
         "followMe": "Enable follow me"
     },
     "videothumbnail":

modules/UI/side_pannels/settings/SettingsMenu.js

-/* global APP, $ */
+/* global APP, $, JitsiMeetJS */
 import UIUtil from "../../util/UIUtil";
 import UIEvents from "../../../../service/UI/UIEvents";
 import languages from "../../../../service/translation/languages";
 
         let $selectCamera= $('#selectCamera'),
             $selectMic = $('#selectMic'),
-            $selectAudioOutput = $('#selectAudioOutput');
+            $selectAudioOutput = $('#selectAudioOutput'),
+            $selectAudioOutputParent = $selectAudioOutput.parent();
 
         let audio = devices.filter(device => device.kind === 'audioinput');
         let video = devices.filter(device => device.kind === 'videoinput');
             generateDevicesOptions(audio, Settings.getMicDeviceId())
         );
 
-        if (audioOutput.length) {
+        if (audioOutput.length &&
+            JitsiMeetJS.isAudioOutputDeviceChangeAvailable()) {
             $selectAudioOutput.html(
                 generateDevicesOptions(audioOutput,
-                    Settings.getAudioOutputDeviceId())
-            ).show();
+                    Settings.getAudioOutputDeviceId()));
+
+            $selectAudioOutputParent.show();
         } else {
-            // if we have no audiooutput devices, that means current browser
-            // doesn't support it, so don't show the select box at all
-            $selectAudioOutput.hide();
+            $selectAudioOutputParent.hide();
         }
 
         $devicesOptions.show();

modules/settings/Settings.js

+/* global JitsiMeetJS */
+
 import UIUtil from '../UI/util/UIUtil';
 
 let email = '';
 let language = null;
 let cameraDeviceId = '';
 let micDeviceId = '';
-let audioOutputDeviceId = '';
 let welcomePageDisabled = false;
 
 function supportsLocalStorage() {
     welcomePageDisabled = JSON.parse(
         window.localStorage.welcomePageDisabled || false
     );
+
+    var audioOutputDeviceId = window.localStorage.audioOutputDeviceId;
+
+    if (typeof audioOutputDeviceId !== 'undefined' &&
+        audioOutputDeviceId !== JitsiMeetJS.getAudioOutputDevice()) {
+        JitsiMeetJS.setAudioOutputDevice(
+            window.localStorage.audioOutputDeviceId).catch((ex) => {
+                console.error('failed to set audio output device from local ' +
+                    'storage', ex);
+            });
+    }
 } else {
     console.log("local storage is not supported");
 }
      * @returns {String}
      */
     getAudioOutputDeviceId: function () {
-        return audioOutputDeviceId;
+        return JitsiMeetJS.getAudioOutputDevice();
     },
     /**
      * Set device id of the audio output device which is currently in use.
      * Empty string stands for default device.
      * @param {string} newId new audio output device id
+     * @returns {Promise}
      */
     setAudioOutputDeviceId: function (newId = '') {
-        audioOutputDeviceId = newId;
-        window.localStorage.audioOutputDeviceId = newId;
+        return JitsiMeetJS.setAudioOutputDevice(newId)
+            .then(() => window.localStorage.audioOutputDeviceId = newId);
     },
 
     /**