feat(MSS): Add support for MediaQualityInfo events

lib/media/quality_observer.js

@@ -266,6 +266,30 @@ shaka.media.QualityObserver = class extends shaka.util.FakeEventTarget {
       contentTypeState.qualityChangePositions = [];
     }
   }
+
+  /**
+   * Create a MediaQualityInfo object from a stream object.
+   *
+   * @param {!shaka.extern.Stream} stream
+   * @return {!shaka.extern.MediaQualityInfo}
+   */
+  static createQualityInfo(stream) {
+    return {
+      bandwidth: stream.bandwidth || 0,
+      audioSamplingRate: stream.audioSamplingRate,
+      codecs: stream.codecs,
+      contentType: stream.type,
+      frameRate: stream.frameRate || null,
+      height: stream.height || null,
+      mimeType: stream.mimeType,
+      channelsCount: stream.channelsCount,
+      pixelAspectRatio: stream.pixelAspectRatio || null,
+      width: stream.width || null,
+      label: stream.label || null,
+      roles: stream.roles,
+      language: stream.language,
+    };
+  }
 };
 
 /**

lib/mss/mss_parser.js

@@ -13,6 +13,7 @@ goog.require('shaka.log');
 goog.require('shaka.media.InitSegmentReference');
 goog.require('shaka.media.ManifestParser');
 goog.require('shaka.media.PresentationTimeline');
+goog.require('shaka.media.QualityObserver');
 goog.require('shaka.media.SegmentIndex');
 goog.require('shaka.media.SegmentReference');
 goog.require('shaka.mss.ContentProtection');
@@ -708,12 +709,14 @@ shaka.mss.MssParser = class {
         initSegmentData = mp4Generator.initSegment();
         this.initSegmentDataByStreamId_.set(stream.id, initSegmentData);
       }
+      const qualityInfo =
+          shaka.media.QualityObserver.createQualityInfo(stream);
       const initSegmentRef = new shaka.media.InitSegmentReference(
           () => [],
           /* startByte= */ 0,
           /* endByte= */ null,
-          /* mediaQuality= */ null,
-          /* timescale= */ undefined,
+          qualityInfo,
+          stream.mssPrivateData.timescale,
           initSegmentData);
 
       const segments = this.createSegments_(initSegmentRef,

lib/player.js

@@ -174,7 +174,7 @@ goog.requireType('shaka.media.PresentationTimeline');
  * @description Fired when the media quality changes at the playhead.
  * That may be caused by an adaptation change or a DASH period transition.
  * Separate events are emitted for audio and video contentTypes.
- * This is supported for only DASH streams at this time.
+ * This is supported for only DASH and MSS streams at this time.
  * @property {string} type
  *   'mediaqualitychanged'
  * @property {shaka.extern.MediaQualityInfo} mediaQuality
@@ -188,7 +188,7 @@ goog.requireType('shaka.media.PresentationTimeline');
  * @event shaka.Player.AudioTrackChangedEvent
  * @description Fired when the audio track changes at the playhead.
  * That may be caused by a user requesting to chang audio tracks.
- * This is supported for only DASH streams at this time.
+ * This is supported for only DASH and MSS streams at this time.
  * @property {string} type
  *   'audiotrackchanged'
  * @property {shaka.extern.MediaQualityInfo} mediaQuality