Audio focus: Re-request audio focus if in a transient loss state

This avoids cases where audio focus is never successfully acquired
because another app is holding on to transient audio focus indefinitely.

Issue: #7182
PiperOrigin-RevId: 305108528

RELEASENOTES.md

@@ -14,6 +14,9 @@
   * Allow missing hours and milliseconds in SubRip (.srt) timecodes
     ([#7122](https://github.com/google/ExoPlayer/issues/7122)).
 * Audio:
+  * Prevent case where another app spuriously holding transient audio focus
+    could prevent ExoPlayer from acquiring audio focus for an indefinite period
+    of time ([#7182](https://github.com/google/ExoPlayer/issues/7182).
   * Workaround issue that could cause slower than realtime playback of AAC on
     Android 10 ([#6671](https://github.com/google/ExoPlayer/issues/6671).
   * Enable playback speed adjustment and silence skipping for floating point PCM

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -39,6 +39,7 @@ import com.google.android.exoplayer2.PlaybackPreparer;
 import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.RenderersFactory;
 import com.google.android.exoplayer2.SimpleExoPlayer;
+import com.google.android.exoplayer2.audio.AudioAttributes;
 import com.google.android.exoplayer2.demo.Sample.UriSample;
 import com.google.android.exoplayer2.drm.DefaultDrmSessionManager;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
@@ -380,6 +381,7 @@ public class PlayerActivity extends AppCompatActivity
               .setTrackSelector(trackSelector)
               .build();
       player.addListener(new PlayerEventListener());
+      player.setAudioAttributes(AudioAttributes.DEFAULT, /* handleAudioFocus= */ true);
       player.setPlayWhenReady(startAutoPlay);
       player.addAnalyticsListener(new EventLogger(trackSelector));
       playerView.setPlayer(player);

library/core/src/main/java/com/google/android/exoplayer2/AudioFocusManager.java

@@ -158,10 +158,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
    */
   @PlayerCommand
   public int updateAudioFocus(boolean playWhenReady, @Player.State int playbackState) {
-    if (!shouldHandleAudioFocus(playbackState)) {
+    if (shouldAbandonAudioFocus(playbackState)) {
-      if (audioFocusState != AUDIO_FOCUS_STATE_NO_FOCUS) {
+      abandonAudioFocus();
-        abandonAudioFocus();
-      }
       return playWhenReady ? PLAYER_COMMAND_PLAY_WHEN_READY : PLAYER_COMMAND_DO_NOT_PLAY;
     }
     return playWhenReady ? requestAudioFocus() : PLAYER_COMMAND_DO_NOT_PLAY;
@@ -174,33 +172,23 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     return focusListener;
   }
 
-  private boolean shouldHandleAudioFocus(@Player.State int playbackState) {
+  private boolean shouldAbandonAudioFocus(@Player.State int playbackState) {
-    return playbackState != Player.STATE_IDLE && focusGain == C.AUDIOFOCUS_GAIN;
+    return playbackState == Player.STATE_IDLE || focusGain != C.AUDIOFOCUS_GAIN;
   }
 
   @PlayerCommand
   private int requestAudioFocus() {
-    int focusRequestResult;
+    if (audioFocusState == AUDIO_FOCUS_STATE_HAVE_FOCUS) {
-
+      return PLAYER_COMMAND_PLAY_WHEN_READY;
-    if (audioFocusState == AUDIO_FOCUS_STATE_NO_FOCUS) {
-      if (Util.SDK_INT >= 26) {
-        focusRequestResult = requestAudioFocusV26();
-      } else {
-        focusRequestResult = requestAudioFocusDefault();
-      }
-      audioFocusState =
-          focusRequestResult == AudioManager.AUDIOFOCUS_REQUEST_GRANTED
-              ? AUDIO_FOCUS_STATE_HAVE_FOCUS
-              : AUDIO_FOCUS_STATE_NO_FOCUS;
     }
-
+    int requestResult = Util.SDK_INT >= 26 ? requestAudioFocusV26() : requestAudioFocusDefault();
-    if (audioFocusState == AUDIO_FOCUS_STATE_NO_FOCUS) {
+    if (requestResult == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
+      audioFocusState = AUDIO_FOCUS_STATE_HAVE_FOCUS;
+      return PLAYER_COMMAND_PLAY_WHEN_READY;
+    } else {
+      audioFocusState = AUDIO_FOCUS_STATE_NO_FOCUS;
       return PLAYER_COMMAND_DO_NOT_PLAY;
     }
-
-    return audioFocusState == AUDIO_FOCUS_STATE_LOSS_TRANSIENT
-        ? PLAYER_COMMAND_WAIT_FOR_CALLBACK
-        : PLAYER_COMMAND_PLAY_WHEN_READY;
   }
 
   private void abandonAudioFocus() {
@@ -388,8 +376,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         (audioFocusState == AUDIO_FOCUS_STATE_LOSS_TRANSIENT_DUCK)
             ? AudioFocusManager.VOLUME_MULTIPLIER_DUCK
             : AudioFocusManager.VOLUME_MULTIPLIER_DEFAULT;
-    if (AudioFocusManager.this.volumeMultiplier != volumeMultiplier) {
+    if (this.volumeMultiplier != volumeMultiplier) {
-      AudioFocusManager.this.volumeMultiplier = volumeMultiplier;
+      this.volumeMultiplier = volumeMultiplier;
       playerControl.setVolumeMultiplier(volumeMultiplier);
     }
   }

library/core/src/test/java/com/google/android/exoplayer2/AudioFocusManagerTest.java

@@ -168,7 +168,7 @@ public class AudioFocusManagerTest {
   }
 
   @Test
-  public void updateAudioFocusFromIdleToBuffering_setsPlayerCommandPlayWhenReady() {
+  public void updateAudioFocus_idleToBuffering_setsPlayerCommandPlayWhenReady() {
     // Ensure that when playWhenReady is true while the player is IDLE, audio focus is only
     // requested after calling prepare (= changing the state to BUFFERING).
     AudioAttributes media = new AudioAttributes.Builder().setUsage(C.USAGE_MEDIA).build();
@@ -188,17 +188,18 @@ public class AudioFocusManagerTest {
   }
 
   @Test
-  public void updateAudioFocusFromPausedToPlaying_setsPlayerCommandPlayWhenReady() {
+  public void updateAudioFocus_pausedToPlaying_setsPlayerCommandPlayWhenReady() {
-    // Ensure that audio focus is not requested until playWhenReady is true.
     AudioAttributes media = new AudioAttributes.Builder().setUsage(C.USAGE_MEDIA).build();
     Shadows.shadowOf(audioManager)
         .setNextFocusRequestResponse(AudioManager.AUDIOFOCUS_REQUEST_GRANTED);
     audioFocusManager.setAudioAttributes(media);
 
+    // Audio focus should not be requested yet, because playWhenReady=false.
     assertThat(audioFocusManager.updateAudioFocus(/* playWhenReady= */ false, Player.STATE_READY))
         .isEqualTo(PLAYER_COMMAND_DO_NOT_PLAY);
     assertThat(Shadows.shadowOf(audioManager).getLastAudioFocusRequest()).isNull();
 
+    // Audio focus should be requested now that playWhenReady=true.
     assertThat(audioFocusManager.updateAudioFocus(/* playWhenReady= */ true, Player.STATE_READY))
         .isEqualTo(PLAYER_COMMAND_PLAY_WHEN_READY);
     ShadowAudioManager.AudioFocusRequest request =
@@ -206,9 +207,28 @@ public class AudioFocusManagerTest {
     assertThat(getAudioFocusGainFromRequest(request)).isEqualTo(AudioManager.AUDIOFOCUS_GAIN);
   }
 
+  // See https://github.com/google/ExoPlayer/issues/7182 for context.
+  @Test
+  public void updateAudioFocus_pausedToPlaying_withTransientLoss_setsPlayerCommandPlayWhenReady() {
+    AudioAttributes media = new AudioAttributes.Builder().setUsage(C.USAGE_MEDIA).build();
+    Shadows.shadowOf(audioManager)
+        .setNextFocusRequestResponse(AudioManager.AUDIOFOCUS_REQUEST_GRANTED);
+    audioFocusManager.setAudioAttributes(media);
+
+    assertThat(audioFocusManager.updateAudioFocus(/* playWhenReady= */ true, Player.STATE_READY))
+        .isEqualTo(PLAYER_COMMAND_PLAY_WHEN_READY);
+
+    // Simulate transient focus loss.
+    audioFocusManager.getFocusListener().onAudioFocusChange(AudioManager.AUDIOFOCUS_LOSS_TRANSIENT);
+
+    // Focus should be re-requested, rather than staying in a state of transient focus loss.
+    assertThat(audioFocusManager.updateAudioFocus(/* playWhenReady= */ true, Player.STATE_READY))
+        .isEqualTo(PLAYER_COMMAND_PLAY_WHEN_READY);
+  }
+
   @Test
   @Config(maxSdk = 25)
-  public void updateAudioFocusFromReadyToIdle_abandonsAudioFocus() {
+  public void updateAudioFocus_readyToIdle_abandonsAudioFocus() {
     // Ensure that stopping the player (=changing state to idle) abandons audio focus.
     AudioAttributes media =
         new AudioAttributes.Builder()
@@ -232,7 +252,7 @@ public class AudioFocusManagerTest {
 
   @Test
   @Config(minSdk = 26, maxSdk = TARGET_SDK)
-  public void updateAudioFocusFromReadyToIdle_abandonsAudioFocus_v26() {
+  public void updateAudioFocus_readyToIdle_abandonsAudioFocus_v26() {
     // Ensure that stopping the player (=changing state to idle) abandons audio focus.
     AudioAttributes media =
         new AudioAttributes.Builder()
@@ -257,7 +277,7 @@ public class AudioFocusManagerTest {
 
   @Test
   @Config(maxSdk = 25)
-  public void updateAudioFocusFromReadyToIdle_withoutHandlingAudioFocus_isNoOp() {
+  public void updateAudioFocus_readyToIdle_withoutHandlingAudioFocus_isNoOp() {
     // Ensure that changing state to idle is a no-op if audio focus isn't handled.
     Shadows.shadowOf(audioManager)
         .setNextFocusRequestResponse(AudioManager.AUDIOFOCUS_REQUEST_GRANTED);
@@ -277,7 +297,7 @@ public class AudioFocusManagerTest {
 
   @Test
   @Config(minSdk = 26, maxSdk = TARGET_SDK)
-  public void updateAudioFocusFromReadyToIdle_withoutHandlingAudioFocus_isNoOp_v26() {
+  public void updateAudioFocus_readyToIdle_withoutHandlingAudioFocus_isNoOp_v26() {
     // Ensure that changing state to idle is a no-op if audio focus isn't handled.
     Shadows.shadowOf(audioManager)
         .setNextFocusRequestResponse(AudioManager.AUDIOFOCUS_REQUEST_GRANTED);