Switches camera id to mandatory when using old gum flow. (#731)

* Switches camera id to mandatory when using old gum flow.

When it fails we retry with different resolutions, and if that doesn't work we remove device id and let gum to decide which device to use.

* Fixes comments.

JitsiMeetJS.js

@@ -38,8 +38,12 @@ const logger = Logger.getLogger(__filename);
 const USER_MEDIA_PERMISSION_PROMPT_TIMEOUT = 1000;
 
 /**
+ * Gets the next lowest desirable resolution to try for a camera.  If the given
+ * resolution is already the lowest acceptable resolution, returns null.
  *
- * @param resolution
+ * @param resolution the current resolution
+ * @return the next lowest resolution from the given one, or null if it is
+ * already the lowest acceptable resolution.
  */
 function getLowerResolution(resolution) {
     if (!Resolutions[resolution]) {
@@ -58,6 +62,10 @@ function getLowerResolution(resolution) {
         }
     });
 
+    if (resName === resolution) {
+        resName = null;
+    }
+
     return resName;
 }
 
@@ -246,11 +254,14 @@ export default {
      *
      * @param {boolean} (firePermissionPromptIsShownEvent) - if event
      *      JitsiMediaDevicesEvents.PERMISSION_PROMPT_IS_SHOWN should be fired
+     * @param originalOptions - internal use only, to be able to store the
+     * originally requested options.
      * @returns {Promise.<{Array.<JitsiTrack>}, JitsiConferenceError>}
      *     A promise that returns an array of created JitsiTracks if resolved,
      *     or a JitsiConferenceError if rejected.
      */
-    createLocalTracks(options = {}, firePermissionPromptIsShownEvent) {
+    createLocalTracks(
+            options = {}, firePermissionPromptIsShownEvent, originalOptions) {
         let promiseFulfilled = false;
 
         if (firePermissionPromptIsShownEvent === true) {
@@ -336,7 +347,23 @@ export default {
                                 reason: 'unsupported resolution'
                             }));
 
-                        return this.createLocalTracks(options);
+                        return this.createLocalTracks(
+                            options,
+                            undefined,
+                            originalOptions || Object.assign({}, options));
+                    }
+
+                    // we tried everything, if there is a mandatory
+                    // device id, remove it and let gum find a device to
+                    // use
+                    if (originalOptions
+                        && error.gum.constraints
+                        && error.gum.constraints.video
+                        && error.gum.constraints.video.mandatory
+                        && error.gum.constraints.video.mandatory.sourceId) {
+                        originalOptions.cameraDeviceId = undefined;
+
+                        return this.createLocalTracks(originalOptions);
                     }
                 }
 

JitsiTrackError.js

@@ -91,6 +91,9 @@ function JitsiTrackError(error, options, devices) {
         case 'OverconstrainedError': {
             const constraintName = error.constraintName || error.constraint;
 
+            // we treat deviceId as unsupported resolution, as we want to
+            // retry and finally if everything fails to remove deviceId from
+            // mandatory constraints
             if (options
                     && options.video
                     && (!devices || devices.indexOf('video') > -1)
@@ -99,7 +102,8 @@ function JitsiTrackError(error, options, devices) {
                         || constraintName === 'minHeight'
                         || constraintName === 'maxHeight'
                         || constraintName === 'width'
-                        || constraintName === 'height')) {
+                        || constraintName === 'height'
+                        || constraintName === 'deviceId')) {
                 this.name = JitsiTrackErrors.UNSUPPORTED_RESOLUTION;
                 this.message
                     = TRACK_ERROR_TO_MESSAGE_MAP[this.name]

modules/RTC/RTCUtils.js

@@ -243,9 +243,7 @@ function getConstraints(um, options = {}) {
             }
 
             // Old style.
-            constraints.video.optional.push({
-                sourceId: options.cameraDeviceId
-            });
+            constraints.video.mandatory.sourceId = options.cameraDeviceId;
         } else {
             // Prefer the front i.e. user-facing camera (to the back i.e.
             // environment-facing camera, for example).