Set initial video quality to large instead of default to avoid automatic switch…

Set initial video quality to large instead of default to avoid automatic switch to HD when iframe resizes. [BLD 981]

CHANGELOG.rst

@@ -5,6 +5,8 @@ These are notable changes in edx-platform.  This is a rolling list of changes,
 in roughly chronological order, most recent first.  Add your entries at or near
 the top.  Include a label indicating the component affected.
 
+Blades: Set initial video quality to large instead of default to avoid automatic switch to HD when iframe resizes. BLD-981.
+
 Blades: Add an upload button for authors to provide students with an option to
 download a handout associated with a video (of arbitrary file format). BLD-1000.
 

common/lib/xmodule/xmodule/js/spec/video/video_quality_control_spec.js

@@ -57,6 +57,12 @@
                     .toEqual(1);
             });
 
+            it('initializes with a quality equal to large', function () {
+                videoPlayer.onPlay();
+
+                expect(player.setPlaybackQuality).toHaveBeenCalledWith('large');
+            });
+
             it('shows the quality control on play if HD is available',
                function () {
                 videoPlayer.onPlay();

common/lib/xmodule/xmodule/js/src/video/05_video_quality_control.js

@@ -104,6 +104,12 @@ function () {
         if (this.config.availableHDQualities.length > 0) {
             this.trigger('videoQualityControl.showQualityControl');
         }
+        // On initialization, force the video quality to be 'large' instead of
+        // 'default'. Otherwise, the player will sometimes switch to HD
+        // automatically, for example when the iframe resizes itself.
+        this.trigger('videoPlayer.handlePlaybackQualityChange',
+            this.videoQualityControl.quality
+        );
     }
 
     function onQualityChange(value) {