diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index a22876ad1a..666522901b 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -6,6 +6,7 @@
   * Add playlist API ([#6161](https://github.com/google/ExoPlayer/issues/6161)).
   * Add `play` and `pause` methods to `Player`.
   * Add `Player.getCurrentLiveOffset` to conveniently return the live offset.
+  * Add `Player.onPlayWhenReadyChanged` with reasons.
   * Make `MediaSourceEventListener.LoadEventInfo` and
     `MediaSourceEventListener.MediaLoadData` top-level classes.
   * Rename `MediaCodecRenderer.onOutputFormatChanged` to
diff --git a/extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java b/extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java
index 5b91410ff9..1202cf1c81 100644
--- a/extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java
+++ b/extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/CastPlayer.java
@@ -351,7 +351,8 @@ public final class CastPlayer extends BasePlayer {
     // We update the local state and send the message to the receiver app, which will cause the
     // operation to be perceived as synchronous by the user. When the operation reports a result,
     // the local state will be updated to reflect the state reported by the Cast SDK.
-    setPlayerStateAndNotifyIfChanged(playWhenReady, playbackState);
+    setPlayerStateAndNotifyIfChanged(
+        playWhenReady, PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST, playbackState);
     flushNotifications();
     PendingResult<MediaChannelResult> pendingResult =
         playWhenReady ? remoteMediaClient.play() : remoteMediaClient.pause();
@@ -625,8 +626,14 @@ public final class CastPlayer extends BasePlayer {
       newPlayWhenReadyValue = !remoteMediaClient.isPaused();
       playWhenReady.clearPendingResultCallback();
     }
+    @PlayWhenReadyChangeReason
+    int playWhenReadyChangeReason =
+        newPlayWhenReadyValue != playWhenReady.value
+            ? PLAY_WHEN_READY_CHANGE_REASON_REMOTE
+            : PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST;
     // We do not mask the playback state, so try setting it regardless of the playWhenReady masking.
-    setPlayerStateAndNotifyIfChanged(newPlayWhenReadyValue, fetchPlaybackState(remoteMediaClient));
+    setPlayerStateAndNotifyIfChanged(
+        newPlayWhenReadyValue, playWhenReadyChangeReason, fetchPlaybackState(remoteMediaClient));
   }
 
   @RequiresNonNull("remoteMediaClient")
@@ -718,13 +725,21 @@ public final class CastPlayer extends BasePlayer {
   }
 
   private void setPlayerStateAndNotifyIfChanged(
-      boolean playWhenReady, @Player.State int playbackState) {
-    if (this.playWhenReady.value != playWhenReady || this.playbackState != playbackState) {
-      this.playWhenReady.value = playWhenReady;
+      boolean playWhenReady,
+      @Player.PlayWhenReadyChangeReason int playWhenReadyChangeReason,
+      @Player.State int playbackState) {
+    boolean playWhenReadyChanged = this.playWhenReady.value != playWhenReady;
+    if (playWhenReadyChanged || this.playbackState != playbackState) {
       this.playbackState = playbackState;
+      this.playWhenReady.value = playWhenReady;
       notificationsBatch.add(
           new ListenerNotificationTask(
-              listener -> listener.onPlayerStateChanged(playWhenReady, playbackState)));
+              listener -> {
+                listener.onPlayerStateChanged(playWhenReady, playbackState);
+                if (playWhenReadyChanged) {
+                  listener.onPlayWhenReadyChanged(playWhenReady, playWhenReadyChangeReason);
+                }
+              }));
     }
   }
 
diff --git a/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java b/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java
index 1346c1f842..55a9b22f9b 100644
--- a/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java
+++ b/extensions/cast/src/test/java/com/google/android/exoplayer2/ext/cast/CastPlayerTest.java
@@ -89,6 +89,8 @@ public class CastPlayerTest {
     verify(mockPendingResult).setResultCallback(setResultCallbackArgumentCaptor.capture());
     assertThat(castPlayer.getPlayWhenReady()).isTrue();
     verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+    verify(mockListener)
+        .onPlayWhenReadyChanged(true, Player.PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
 
     // There is a status update in the middle, which should be hidden by masking.
     remoteMediaClientListener.onStatusUpdated();
@@ -111,21 +113,42 @@ public class CastPlayerTest {
     verify(mockPendingResult).setResultCallback(setResultCallbackArgumentCaptor.capture());
     assertThat(castPlayer.getPlayWhenReady()).isTrue();
     verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+    verify(mockListener)
+        .onPlayWhenReadyChanged(true, Player.PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
 
     // Upon result, the remote media client is still paused. The state should reflect that.
     setResultCallbackArgumentCaptor
         .getValue()
         .onResult(Mockito.mock(RemoteMediaClient.MediaChannelResult.class));
     verify(mockListener).onPlayerStateChanged(false, Player.STATE_IDLE);
+    verify(mockListener).onPlayWhenReadyChanged(false, Player.PLAY_WHEN_READY_CHANGE_REASON_REMOTE);
     assertThat(castPlayer.getPlayWhenReady()).isFalse();
   }
 
+  @Test
+  public void testSetPlayWhenReady_correctChangeReasonOnPause() {
+    when(mockRemoteMediaClient.play()).thenReturn(mockPendingResult);
+    when(mockRemoteMediaClient.pause()).thenReturn(mockPendingResult);
+    castPlayer.play();
+    assertThat(castPlayer.getPlayWhenReady()).isTrue();
+    verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+    verify(mockListener)
+        .onPlayWhenReadyChanged(true, Player.PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
+
+    castPlayer.pause();
+    assertThat(castPlayer.getPlayWhenReady()).isFalse();
+    verify(mockListener).onPlayerStateChanged(false, Player.STATE_IDLE);
+    verify(mockListener)
+        .onPlayWhenReadyChanged(false, Player.PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
+  }
+
   @Test
   public void testPlayWhenReady_changesOnStatusUpdates() {
     assertThat(castPlayer.getPlayWhenReady()).isFalse();
     when(mockRemoteMediaClient.isPaused()).thenReturn(false);
     remoteMediaClientListener.onStatusUpdated();
     verify(mockListener).onPlayerStateChanged(true, Player.STATE_IDLE);
+    verify(mockListener).onPlayWhenReadyChanged(true, Player.PLAY_WHEN_READY_CHANGE_REASON_REMOTE);
     assertThat(castPlayer.getPlayWhenReady()).isTrue();
   }
 
diff --git a/extensions/ima/src/test/java/com/google/android/exoplayer2/ext/ima/FakePlayer.java b/extensions/ima/src/test/java/com/google/android/exoplayer2/ext/ima/FakePlayer.java
index e3af8dbb8f..b89b23516c 100644
--- a/extensions/ima/src/test/java/com/google/android/exoplayer2/ext/ima/FakePlayer.java
+++ b/extensions/ima/src/test/java/com/google/android/exoplayer2/ext/ima/FakePlayer.java
@@ -93,12 +93,17 @@ import java.util.ArrayList;
 
   /** Sets the {@link Player.State} of this player. */
   public void setState(@Player.State int state, boolean playWhenReady) {
-    boolean notify = this.state != state || this.playWhenReady != playWhenReady;
+    boolean playWhenReadyChanged = this.playWhenReady != playWhenReady;
+    boolean playerStateChanged = this.state != state || playWhenReadyChanged;
     this.state = state;
     this.playWhenReady = playWhenReady;
-    if (notify) {
+    if (playerStateChanged) {
       for (Player.EventListener listener : listeners) {
         listener.onPlayerStateChanged(playWhenReady, state);
+        if (playWhenReadyChanged) {
+          listener.onPlayWhenReadyChanged(
+              playWhenReady, PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
+        }
       }
     }
   }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java b/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java
index af11bcd868..161ea9c6ee 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java
@@ -424,11 +424,16 @@ import java.util.concurrent.TimeoutException;
 
   @Override
   public void setPlayWhenReady(boolean playWhenReady) {
-    setPlayWhenReady(playWhenReady, PLAYBACK_SUPPRESSION_REASON_NONE);
+    setPlayWhenReady(
+        playWhenReady,
+        PLAYBACK_SUPPRESSION_REASON_NONE,
+        PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST);
   }
 
   public void setPlayWhenReady(
-      boolean playWhenReady, @PlaybackSuppressionReason int playbackSuppressionReason) {
+      boolean playWhenReady,
+      @PlaybackSuppressionReason int playbackSuppressionReason,
+      @PlayWhenReadyChangeReason int playWhenReadyChangeReason) {
     boolean oldIsPlaying = isPlaying();
     boolean oldInternalPlayWhenReady =
         this.playWhenReady && this.playbackSuppressionReason == PLAYBACK_SUPPRESSION_REASON_NONE;
@@ -450,6 +455,9 @@ import java.util.concurrent.TimeoutException;
             if (playWhenReadyChanged) {
               listener.onPlayerStateChanged(playWhenReady, playbackState);
             }
+            if (playWhenReadyChanged) {
+              listener.onPlayWhenReadyChanged(playWhenReady, playWhenReadyChangeReason);
+            }
             if (suppressionReasonChanged) {
               listener.onPlaybackSuppressionReasonChanged(playbackSuppressionReason);
             }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/Player.java b/library/core/src/main/java/com/google/android/exoplayer2/Player.java
index 1f1c23a980..c6bdb424e9 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/Player.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/Player.java
@@ -418,6 +418,15 @@ public interface Player {
      */
     default void onPlayerStateChanged(boolean playWhenReady, @State int playbackState) {}
 
+    /**
+     * Called when the value returned from {@link #getPlayWhenReady()} changes.
+     *
+     * @param playWhenReady Whether playback will proceed when ready.
+     * @param reason The {@link PlayWhenReadyChangeReason reason} for the change.
+     */
+    default void onPlayWhenReadyChanged(
+        boolean playWhenReady, @PlayWhenReadyChangeReason int reason) {}
+
     /**
      * Called when the value returned from {@link #getPlaybackSuppressionReason()} changes.
      *
@@ -549,6 +558,31 @@ public interface Player {
    */
   int STATE_ENDED = 4;
 
+  /**
+   * Reasons for {@link #getPlayWhenReady() playWhenReady} changes. One of {@link
+   * #PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST}, {@link
+   * #PLAY_WHEN_READY_CHANGE_REASON_AUDIO_FOCUS_LOSS}, {@link
+   * #PLAY_WHEN_READY_CHANGE_REASON_AUDIO_BECOMING_NOISY} or {@link
+   * #PLAY_WHEN_READY_CHANGE_REASON_REMOTE}.
+   */
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({
+    PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST,
+    PLAY_WHEN_READY_CHANGE_REASON_AUDIO_FOCUS_LOSS,
+    PLAY_WHEN_READY_CHANGE_REASON_AUDIO_BECOMING_NOISY,
+    PLAY_WHEN_READY_CHANGE_REASON_REMOTE
+  })
+  @interface PlayWhenReadyChangeReason {}
+  /** Playback has been started or paused by the user. */
+  int PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST = 1;
+  /** Playback has been paused because of a loss of audio focus. */
+  int PLAY_WHEN_READY_CHANGE_REASON_AUDIO_FOCUS_LOSS = 2;
+  /** Playback has been paused to avoid becoming noisy. */
+  int PLAY_WHEN_READY_CHANGE_REASON_AUDIO_BECOMING_NOISY = 3;
+  /** Playback has been started or paused because of a remote change. */
+  int PLAY_WHEN_READY_CHANGE_REASON_REMOTE = 4;
+
   /**
    * Reason why playback is suppressed even though {@link #getPlayWhenReady()} is {@code true}. One
    * of {@link #PLAYBACK_SUPPRESSION_REASON_NONE} or {@link
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java b/library/core/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java
index ef7e715b6e..7e0bed5f3f 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java
@@ -688,11 +688,13 @@ public class SimpleExoPlayer extends BasePlayer
       }
     }
 
+    boolean playWhenReady = getPlayWhenReady();
     @AudioFocusManager.PlayerCommand
     int playerCommand =
         audioFocusManager.setAudioAttributes(
-            handleAudioFocus ? audioAttributes : null, getPlayWhenReady(), getPlaybackState());
-    updatePlayWhenReady(getPlayWhenReady(), playerCommand);
+            handleAudioFocus ? audioAttributes : null, playWhenReady, getPlaybackState());
+    updatePlayWhenReady(
+        playWhenReady, playerCommand, getPlayWhenReadyChangeReason(playWhenReady, playerCommand));
   }
 
   @Override
@@ -1179,9 +1181,11 @@ public class SimpleExoPlayer extends BasePlayer
   @Override
   public void prepare() {
     verifyApplicationThread();
+    boolean playWhenReady = getPlayWhenReady();
     @AudioFocusManager.PlayerCommand
-    int playerCommand = audioFocusManager.handlePrepare(getPlayWhenReady());
-    updatePlayWhenReady(getPlayWhenReady(), playerCommand);
+    int playerCommand = audioFocusManager.handlePrepare(playWhenReady);
+    updatePlayWhenReady(
+        playWhenReady, playerCommand, getPlayWhenReadyChangeReason(playWhenReady, playerCommand));
     player.prepare();
   }
 
@@ -1318,7 +1322,8 @@ public class SimpleExoPlayer extends BasePlayer
     verifyApplicationThread();
     @AudioFocusManager.PlayerCommand
     int playerCommand = audioFocusManager.handleSetPlayWhenReady(playWhenReady, getPlaybackState());
-    updatePlayWhenReady(playWhenReady, playerCommand);
+    updatePlayWhenReady(
+        playWhenReady, playerCommand, getPlayWhenReadyChangeReason(playWhenReady, playerCommand));
   }
 
   @Override
@@ -1634,14 +1639,16 @@ public class SimpleExoPlayer extends BasePlayer
   }
 
   private void updatePlayWhenReady(
-      boolean playWhenReady, @AudioFocusManager.PlayerCommand int playerCommand) {
+      boolean playWhenReady,
+      @AudioFocusManager.PlayerCommand int playerCommand,
+      @Player.PlayWhenReadyChangeReason int playWhenReadyChangeReason) {
     playWhenReady = playWhenReady && playerCommand != AudioFocusManager.PLAYER_COMMAND_DO_NOT_PLAY;
     @PlaybackSuppressionReason
     int playbackSuppressionReason =
         playWhenReady && playerCommand != AudioFocusManager.PLAYER_COMMAND_PLAY_WHEN_READY
             ? Player.PLAYBACK_SUPPRESSION_REASON_TRANSIENT_AUDIO_FOCUS_LOSS
             : Player.PLAYBACK_SUPPRESSION_REASON_NONE;
-    player.setPlayWhenReady(playWhenReady, playbackSuppressionReason);
+    player.setPlayWhenReady(playWhenReady, playbackSuppressionReason, playWhenReadyChangeReason);
   }
 
   private void verifyApplicationThread() {
@@ -1655,6 +1662,12 @@ public class SimpleExoPlayer extends BasePlayer
     }
   }
 
+  private static int getPlayWhenReadyChangeReason(boolean playWhenReady, int playerCommand) {
+    return playWhenReady && playerCommand != AudioFocusManager.PLAYER_COMMAND_PLAY_WHEN_READY
+        ? PLAY_WHEN_READY_CHANGE_REASON_AUDIO_FOCUS_LOSS
+        : PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST;
+  }
+
   private final class ComponentListener
       implements VideoRendererEventListener,
           AudioRendererEventListener,
@@ -1872,14 +1885,23 @@ public class SimpleExoPlayer extends BasePlayer
 
     @Override
     public void executePlayerCommand(@AudioFocusManager.PlayerCommand int playerCommand) {
-      updatePlayWhenReady(getPlayWhenReady(), playerCommand);
+      boolean playWhenReady = getPlayWhenReady();
+      updatePlayWhenReady(
+          playWhenReady, playerCommand, getPlayWhenReadyChangeReason(playWhenReady, playerCommand));
     }
 
     // AudioBecomingNoisyManager.EventListener implementation.
 
     @Override
     public void onAudioBecomingNoisy() {
-      pause();
+      // Command is always PLAYER_COMMAND_DO_NOT_PLAY but the call is needed to abandon the
+      // audio focus if the focus is currently held.
+      int playerCommand =
+          audioFocusManager.handleSetPlayWhenReady(/* playWhenReady= */ false, getPlaybackState());
+      updatePlayWhenReady(
+          /* playWhenReady= */ false,
+          playerCommand,
+          Player.PLAY_WHEN_READY_CHANGE_REASON_AUDIO_BECOMING_NOISY);
     }
 
     // Player.EventListener implementation.
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java b/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java
index 9fa9257459..7cfa532e83 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java
@@ -446,6 +446,15 @@ public class AnalyticsCollector
     }
   }
 
+  @Override
+  public final void onPlayWhenReadyChanged(
+      boolean playWhenReady, @Player.PlayWhenReadyChangeReason int reason) {
+    EventTime eventTime = generateCurrentPlayerMediaPeriodEventTime();
+    for (AnalyticsListener listener : listeners) {
+      listener.onPlayWhenReadyChanged(eventTime, playWhenReady, reason);
+    }
+  }
+
   @Override
   public void onPlaybackSuppressionReasonChanged(
       @PlaybackSuppressionReason int playbackSuppressionReason) {
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java b/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java
index 353e7ac340..5f49fd22a9 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java
@@ -133,6 +133,16 @@ public interface AnalyticsListener {
   default void onPlayerStateChanged(
       EventTime eventTime, boolean playWhenReady, @Player.State int playbackState) {}
 
+  /**
+   * Called when the value changed that indicates whether playback will proceed when ready.
+   *
+   * @param eventTime The event time.
+   * @param playWhenReady Whether playback will proceed when ready.
+   * @param reason The {@link Player.PlayWhenReadyChangeReason reason} of the change.
+   */
+  default void onPlayWhenReadyChanged(
+      EventTime eventTime, boolean playWhenReady, @Player.PlayWhenReadyChangeReason int reason) {}
+
   /**
    * Called when playback suppression reason changed.
    *
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/util/EventLogger.java b/library/core/src/main/java/com/google/android/exoplayer2/util/EventLogger.java
index 6d5820d1f3..3cf118d943 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/util/EventLogger.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/util/EventLogger.java
@@ -98,7 +98,16 @@ public class EventLogger implements AnalyticsListener {
   @Override
   public void onPlayerStateChanged(
       EventTime eventTime, boolean playWhenReady, @Player.State int state) {
-    logd(eventTime, "state", playWhenReady + ", " + getStateString(state));
+    logd(eventTime, "state", getStateString(state));
+  }
+
+  @Override
+  public void onPlayWhenReadyChanged(
+      EventTime eventTime, boolean playWhenReady, @Player.PlayWhenReadyChangeReason int reason) {
+    logd(
+        eventTime,
+        "playWhenReady",
+        playWhenReady + ", " + getPlayWhenReadyChangeReasonString(reason));
   }
 
   @Override
@@ -637,4 +646,20 @@ public class EventLogger implements AnalyticsListener {
         return "?";
     }
   }
+
+  private static String getPlayWhenReadyChangeReasonString(
+      @Player.PlayWhenReadyChangeReason int reason) {
+    switch (reason) {
+      case Player.PLAY_WHEN_READY_CHANGE_REASON_AUDIO_BECOMING_NOISY:
+        return "AUDIO_BECOMING_NOISY";
+      case Player.PLAY_WHEN_READY_CHANGE_REASON_AUDIO_FOCUS_LOSS:
+        return "AUDIO_FOCUS_LOSS";
+      case Player.PLAY_WHEN_READY_CHANGE_REASON_REMOTE:
+        return "REMOTE";
+      case Player.PLAY_WHEN_READY_CHANGE_REASON_USER_REQUEST:
+        return "USER_REQUEST";
+      default:
+        return "?";
+    }
+  }
 }