fix: Do not update the player position with negative playback rates if the video is paused (#9732)

lib/media/play_rate_controller.js

@@ -39,7 +39,9 @@ shaka.media.PlayRateController = class {
 
     /** @private {shaka.util.Timer} */
     this.timer_ = new shaka.util.Timer(() => {
-      this.harness_.movePlayhead(this.rate_ * this.pollRate_);
+      if (!this.harness_.isPaused()) {
+        this.harness_.movePlayhead(this.rate_ * this.pollRate_);
+      }
     });
   }
 
@@ -172,6 +174,7 @@ shaka.media.PlayRateController = class {
  *   getDefaultRate: function():number,
  *   setRate: function(number),
  *   movePlayhead: function(number),
+ *   isPaused: function():boolean,
  * }}
  *
  * @description
@@ -192,5 +195,8 @@ shaka.media.PlayRateController = class {
  *   Move the playhead N seconds. If N is positive, the playhead will move
  *   forward abs(N) seconds. If N is negative, the playhead will move backwards
  *   abs(N) seconds.
+ *
+ * @property {function():boolean} isPaused
+ *   Get if the current playback is paused.
  */
 shaka.media.PlayRateController.Harness;

lib/player.js

@@ -2725,6 +2725,20 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     this.mediaSourceEngine_ = mediaSourceEngine;
   }
 
+  /**
+   * @param {HTMLMediaElement} mediaElement
+   * @private
+   */
+  setupPlayRateController_(mediaElement) {
+    this.playRateController_ = new shaka.media.PlayRateController({
+      getRate: () => mediaElement.playbackRate,
+      getDefaultRate: () => mediaElement.defaultPlaybackRate,
+      setRate: (rate) => { mediaElement.playbackRate = rate; },
+      movePlayhead: (delta) => { mediaElement.currentTime += delta; },
+      isPaused: () => mediaElement.paused,
+    });
+  }
+
   /**
    * Adds the basic media listeners
    *
@@ -2874,12 +2888,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     this.makeStateChangeEvent_('load');
 
     const mediaElement = this.video_;
-    this.playRateController_ = new shaka.media.PlayRateController({
-      getRate: () => mediaElement.playbackRate,
-      getDefaultRate: () => mediaElement.defaultPlaybackRate,
-      setRate: (rate) => { mediaElement.playbackRate = rate; },
-      movePlayhead: (delta) => { mediaElement.currentTime += delta; },
-    });
+    this.setupPlayRateController_(mediaElement);
 
     // Add all media element listeners.
     this.addBasicMediaListeners_(mediaElement, startTimeOfLoad);
@@ -3253,12 +3262,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
     this.playheadObservers_ =
         this.createPlayheadObserversForSrcEquals_(this.startTime_ || 0);
 
-    this.playRateController_ = new shaka.media.PlayRateController({
-      getRate: () => mediaElement.playbackRate,
-      getDefaultRate: () => mediaElement.defaultPlaybackRate,
-      setRate: (rate) => { mediaElement.playbackRate = rate; },
-      movePlayhead: (delta) => { mediaElement.currentTime += delta; },
-    });
+    this.setupPlayRateController_(mediaElement);
 
     this.startBufferManagement_(mediaElement, /* srcEquals= */ true);
 

test/media/play_rate_controller_unit.js

@@ -13,6 +13,8 @@ describe('PlayRateController', () => {
   let setPlayRateSpy;
   /** @type {!jasmine.Spy} */
   let movePlayheadSpy;
+  /** @type {!jasmine.Spy} */
+  let isPausedSpy;
 
   /** @type {number} */
   let playRate;
@@ -25,6 +27,7 @@ describe('PlayRateController', () => {
     getDefaultPlayRateSpy = jasmine.createSpy('getDefaultPlaybackRate');
     setPlayRateSpy = jasmine.createSpy('setPlaybackRate');
     movePlayheadSpy = jasmine.createSpy('movePlayhead');
+    isPausedSpy = jasmine.createSpy('isPaused');
 
     playRate = 1;
 
@@ -32,12 +35,14 @@ describe('PlayRateController', () => {
     setPlayRateSpy.and.callFake((rate) => {
       playRate = rate;
     });
+    isPausedSpy.and.callFake(() => false);
 
     const harness = {
       getRate: shaka.test.Util.spyFunc(getPlayRateSpy),
       getDefaultRate: shaka.test.Util.spyFunc(getDefaultPlayRateSpy),
       setRate: shaka.test.Util.spyFunc(setPlayRateSpy),
       movePlayhead: shaka.test.Util.spyFunc(movePlayheadSpy),
+      isPaused: shaka.test.Util.spyFunc(isPausedSpy),
     };
 
     controller = new shaka.media.PlayRateController(harness);