feat(audio-only): be able to lock a browser into capturing audio only

JitsiMediaDevices.js

@@ -138,6 +138,18 @@ const JitsiMediaDevices = {
      */
     emitEvent(event, ...args) {
         eventEmitter.emit(event, ...args);
+    },
+
+    /**
+     * Returns whether or not the current browser can support capturing video,
+     * be it camera or desktop, and displaying received video.
+     *
+     * @returns {boolean}
+     */
+    supportsVideo() {
+        // Defer to RTCBrowserType to allow exposure of the api to the consumer
+        // but prevent other files from having to import JitsiMediaDevices.
+        return RTCBrowserType.supportsVideo();
     }
 };
 

modules/RTC/RTCBrowserType.js

@@ -283,6 +283,17 @@ const RTCBrowserType = {
 
     supportsRtpSender() {
         return RTCBrowserType.isFirefox();
+    },
+
+    /**
+     * Returns whether or not the current browser can support capturing video,
+     * be it camera or desktop, and displaying received video.
+     *
+     * @returns {boolean}
+     */
+    supportsVideo() {
+        // Currently all browsers are assumed to support video.
+        return true;
     }
 
     // Add version getters for other browsers when needed

modules/RTC/RTCUtils.js

@@ -1231,7 +1231,7 @@ class RTCUtils extends Listenable {
     _newGetDesktopMedia(
             desktopSharingExtensionExternalInstallation,
             desktopSharingSources) {
-        if (!screenObtainer.isSupported()) {
+        if (!screenObtainer.isSupported() || !RTCBrowserType.supportsVideo()) {
             return Promise.reject(
                 new Error('Desktop sharing is not supported!'));
         }
@@ -1505,8 +1505,9 @@ class RTCUtils extends Listenable {
          */
         const maybeRequestCaptureDevices = function() {
             const umDevices = options.devices || [ 'audio', 'video' ];
-            const requestedCaptureDevices = umDevices.filter(
-                device => device !== 'desktop');
+            const requestedCaptureDevices = umDevices.filter(device =>
+                device === 'audio'
+                || (device === 'video' && RTCBrowserType.supportsVideo()));
 
             if (!requestedCaptureDevices.length) {
                 return Promise.resolve();