Manage audio focus

Two or more Android apps can play audio to the same output stream simultaneously, and the system mixes everything together. While this is technically impressive, it can be very aggravating to a user. To avoid every music app playing at the same time, Android introduces the idea of audio focus. Only one app can hold audio focus at a time.

When your app needs to output audio, it should request audio focus. When it has focus, it can play sound. However, after you acquire audio focus you may not be able to keep it until you’re done playing. Another app can request focus, which preempts your hold on audio focus. If that happens, your app should pause playing or lower its volume to let users hear the new audio source more easily.

Before Android 12 (API level 31), audio focus is not managed by the system. So, while app developers are encouraged to comply with the audio focus guidelines, if an app continues to play loudly even after losing audio focus on a device running Android 11 (API level 30) or lower, the system can't prevent it. However, this app behavior leads to a bad user experience and can often lead users to uninstall the misbehaving app.

A well-designed audio app should manage audio focus according to these general guidelines:

• Call requestAudioFocus() immediately before starting to play and verify that the call returns AUDIOFOCUS_REQUEST_GRANTED. Make the call to requestAudioFocus() in the onPlay() callback of your media session.

• When another app gains audio focus, stop or pause playing, or duck (that is, reduce) the volume.

• When playback stops (for example, when the app has nothing left to play), abandon audio focus. Your app doesn't have to abandon audio focus if the user pauses playback but might resume playback later.

• Use AudioAttributes to describe the type of audio your app is playing. For example, for apps that play speech, specify CONTENT_TYPE_SPEECH.

Audio focus is handled differently depending on the version of Android that is running:

Android 12 (API level 31) or later

Audio focus is managed by the system. The system forces audio playback from an app to fade out when another app requests audio focus. The system also mutes audio playback when an incoming call is received.

Android 8.0 (API level 26) through Android 11 (API level 30)

Audio focus is not managed by the system, but includes some changes that were introduced starting in Android 8.0 (API level 26).

Android 7.1 (API level 25) and lower

Audio focus is not managed by the system, and apps manage audio focus using the requestAudioFocus() and abandonAudioFocus().

Audio focus in Android 12 and higher

A media or game app that uses audio focus shouldn't play audio after it loses focus. In Android 12 (API level 31) and higher, the system enforces this behavior. When an app requests audio focus while another app has the focus and is playing, the system forces the playing app to fade out. The addition of the fade-out provides a smoother transition when going from one app to another.

This fade out behavior happens when the following conditions are met:

1. The first, currently playing app meets all of these criteria:

   • The app has either the AudioAttributes.USAGE_MEDIA or AudioAttributes.USAGE_GAME usage attribute.
   • The app successfully requested audio focus with AudioManager.AUDIOFOCUS_GAIN.
   • The app is not playing audio with content type AudioAttributes.CONTENT_TYPE_SPEECH.

2. A second app requests audio focus with AudioManager.AUDIOFOCUS_GAIN.

When these conditions are met, the audio system fades out the first app. At the end of the fade out, the system notifies the first app of focus loss. The app's players remain muted until the app requests audio focus again.

Existing audio focus behaviors

You should also be aware of these other cases that involve a switch in audio focus.

Automatic ducking

Automatic ducking (temporarily reducing the audio level of one app so that another can be heard clearly) was introduced in Android 8.0 (API level 26).

By having the system implement ducking, you don't have to implement ducking in your app.

Automatic ducking also occurs when an audio notification grabs the focus from a playing app. The start of the notification playback is synchronized with the end of the ducking ramp.

Automatic ducking happens when the following conditions are met:

1. The first, currently-playing app meets all of these criteria:

   • The app successfully requested audio focus with any type of focus gain.
   • The app is not playing audio with content type AudioAttributes.CONTENT_TYPE_SPEECH.
   • The app did not set AudioFocusRequest.Builder.setWillPauseWhenDucked(true).

2. A second app requests audio focus with AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK.

When these conditions are met, the audio system ducks all the active players of the first app while the second app has focus. When the second app abandons focus, it unducks them. The first app is not notified when it loses focus, so it doesn’t have to do anything.

Note that automatic ducking is not performed when the user is listening to speech content, because the user might miss some of the program. For example, voice guidance for driving directions are not ducked.

Mute current audio playback for incoming phone calls

Some apps don't behave properly and continue playing audio during phone calls. This situation forces the user to find and mute or quit the offending app in order to hear their call. To prevent this, the system can mute audio from other apps while there is an incoming call. The system invokes this feature when an a incoming phone call is received and an app meets these conditions:

• The app has either the AudioAttributes.USAGE_MEDIA or AudioAttributes.USAGE_GAME usage attribute.
• The app successfully requested audio focus (any focus gain) and is playing audio.

If an app continues playing during the call, its playback is muted until the call ends. However, if an app starts playing during the call, that player is not muted on the assumption that the user started playback intentionally.

Audio focus in Android 8.0 through Android 11

Beginning with Android 8.0 (API level 26), when you call requestAudioFocus() you must supply an AudioFocusRequest parameter. The AudioFocusRequest contains information about the audio context and capabilities of your app. The system uses this information to manage the gain and loss of audio focus automatically. To release audio focus, call the method abandonAudioFocusRequest() which also takes an AudioFocusRequest as its argument. Use the same AudioFocusRequest instance both when you request and abandon focus.

To create an AudioFocusRequest, use an AudioFocusRequest.Builder. Since a focus request must always specify the type of the request, the type is included in the constructor for the builder. Use the builder's methods to set the other fields of the request.

The FocusGain field is required; all the other fields are optional.

The following example shows how to use an AudioFocusRequest.Builder to build an AudioFocusRequest and request and abandon audio focus:

// initializing variables for audio focus and playback management audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager focusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN).run {     setAudioAttributes(AudioAttributes.Builder().run {         setUsage(AudioAttributes.USAGE_GAME)         setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)         build()     })     setAcceptsDelayedFocusGain(true)     setOnAudioFocusChangeListener(afChangeListener, handler)     build() } val focusLock = Any()  var playbackDelayed = false var playbackNowAuthorized = false  // requesting audio focus and processing the response val res = audioManager.requestAudioFocus(focusRequest) synchronized(focusLock) {     playbackNowAuthorized = when (res) {         AudioManager.AUDIOFOCUS_REQUEST_FAILED -> false         AudioManager.AUDIOFOCUS_REQUEST_GRANTED -> {             playbackNow()             true         }         AudioManager.AUDIOFOCUS_REQUEST_DELAYED -> {             playbackDelayed = true             false         }         else -> false     } }  // implementing OnAudioFocusChangeListener to react to focus changes override fun onAudioFocusChange(focusChange: Int) {     when (focusChange) {         AudioManager.AUDIOFOCUS_GAIN ->             if (playbackDelayed || resumeOnFocusGain) {                 synchronized(focusLock) {                     playbackDelayed = false                     resumeOnFocusGain = false                 }                 playbackNow()             }         AudioManager.AUDIOFOCUS_LOSS -> {             synchronized(focusLock) {                 resumeOnFocusGain = false                 playbackDelayed = false             }             pausePlayback()         }         AudioManager.AUDIOFOCUS_LOSS_TRANSIENT -> {             synchronized(focusLock) {                 // only resume if playback is being interrupted                 resumeOnFocusGain = isPlaying()                 playbackDelayed = false             }             pausePlayback()         }         AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK -> {             // ... pausing or ducking depends on your app         }     } }

// initializing variables for audio focus and playback management audioManager = (AudioManager) Context.getSystemService(Context.AUDIO_SERVICE); playbackAttributes = new AudioAttributes.Builder()         .setUsage(AudioAttributes.USAGE_GAME)         .setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)         .build(); focusRequest = new AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN)         .setAudioAttributes(playbackAttributes)         .setAcceptsDelayedFocusGain(true)         .setOnAudioFocusChangeListener(afChangeListener, handler)         .build(); final Object focusLock = new Object();  boolean playbackDelayed = false; boolean playbackNowAuthorized = false;  // requesting audio focus and processing the response int res = audioManager.requestAudioFocus(focusRequest); synchronized(focusLock) {     if (res == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {         playbackNowAuthorized = false;     } else if (res == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {         playbackNowAuthorized = true;         playbackNow();     } else if (res == AudioManager.AUDIOFOCUS_REQUEST_DELAYED) {         playbackDelayed = true;         playbackNowAuthorized = false;     } }  // implementing OnAudioFocusChangeListener to react to focus changes @Override public void onAudioFocusChange(int focusChange) {     switch (focusChange) {         case AudioManager.AUDIOFOCUS_GAIN:             if (playbackDelayed || resumeOnFocusGain) {                 synchronized(focusLock) {                     playbackDelayed = false;                     resumeOnFocusGain = false;                 }                 playbackNow();             }             break;         case AudioManager.AUDIOFOCUS_LOSS:             synchronized(focusLock) {                 resumeOnFocusGain = false;                 playbackDelayed = false;             }             pausePlayback();             break;         case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:             synchronized(focusLock) {                 // only resume if playback is being interrupted                 resumeOnFocusGain = isPlaying();                 playbackDelayed = false;             }             pausePlayback();             break;         case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:             // ... pausing or ducking depends on your app             break;         }     } }

Automatic ducking

In Android 8.0 (API level 26), when another app requests focus with AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK the system can duck and restore the volume without invoking the app's onAudioFocusChange() callback.

While automatic ducking is acceptable behavior for music and video playback apps, it isn't useful when playing spoken content, such as in an audio book app. In this case, the app should pause instead.

If you want your app to pause when asked to duck rather than decrease its volume, create an OnAudioFocusChangeListener with an onAudioFocusChange() callback method that implements the desired pause/resume behavior. Call setOnAudioFocusChangeListener() to register the listener, and call setWillPauseWhenDucked(true) to tell the system to use your callback rather than perform automatic ducking.

Delayed focus gain

Sometimes the system cannot grant a request for audio focus because the focus is "locked" by another app, such as during a phone call. In this case, requestAudioFocus() returns AUDIOFOCUS_REQUEST_FAILED. When this happens, your app should not proceed with audio playback because it did not gain focus.

The method, setAcceptsDelayedFocusGain(true), that lets your app handle a request for focus asynchronously. With this flag set, a request made when the focus is locked returns AUDIOFOCUS_REQUEST_DELAYED. When the condition that locked the audio focus no longer exists, such as when a phone call ends, the system grants the pending focus request and calls onAudioFocusChange() to notify your app.

In order to handle the delayed gain of focus, you must create an OnAudioFocusChangeListener with an onAudioFocusChange() callback method that implements the desired behavior and register the listener by calling setOnAudioFocusChangeListener().

Audio focus in Android 7.1 and lower

When you call requestAudioFocus() you must specify a duration hint, which may be honored by another app that is currently holding focus and playing:

• Request permanent audio focus (AUDIOFOCUS_GAIN) when you plan to play audio for the foreseeable future (for example, when playing music) and you expect the previous holder of audio focus to stop playing.
• Request transient focus (AUDIOFOCUS_GAIN_TRANSIENT) when you expect to play audio for only a short time and you expect the previous holder to pause playing.
• Request transient focus with ducking (AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK) to indicate that you expect to play audio for only a short time and that it's OK for the previous focus owner to keep playing if it "ducks" (lowers) its audio output. Both audio outputs are mixed into the audio stream. Ducking is particularly suitable for apps that use the audio stream intermittently, such as for audible driving directions.

The requestAudioFocus() method also requires an AudioManager.OnAudioFocusChangeListener. This listener should be created in the same activity or service that owns your media session. It implements the callback onAudioFocusChange() that your app receives when some other app acquires or abandons audio focus.

The following snippet requests permanent audio focus on the stream STREAM_MUSIC and registers an OnAudioFocusChangeListener to handle subsequent changes in audio focus. (The change listener is discussed in Responding to an audio focus change.)

audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager lateinit var afChangeListener AudioManager.OnAudioFocusChangeListener  ... // Request audio focus for playback val result: Int = audioManager.requestAudioFocus(         afChangeListener,         // Use the music stream.         AudioManager.STREAM_MUSIC,         // Request permanent focus.         AudioManager.AUDIOFOCUS_GAIN )  if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {     // Start playback }

AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); AudioManager.OnAudioFocusChangeListener afChangeListener;  ... // Request audio focus for playback int result = audioManager.requestAudioFocus(afChangeListener,                              // Use the music stream.                              AudioManager.STREAM_MUSIC,                              // Request permanent focus.                              AudioManager.AUDIOFOCUS_GAIN);  if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {     // Start playback }

When you finish playback, call abandonAudioFocus().

audioManager.abandonAudioFocus(afChangeListener)

// Abandon audio focus when playback complete audioManager.abandonAudioFocus(afChangeListener);

This notifies the system that you no longer require focus and unregisters the associated OnAudioFocusChangeListener. If you requested transient focus, this will notify an app that paused or ducked that it may continue playing or restore its volume.

Responding to an audio focus change

When an app acquires audio focus, it must be able to release it when another app requests audio focus for itself. When this happens, your app receives a call to the onAudioFocusChange() method in the AudioFocusChangeListener that you specified when the app called requestAudioFocus().

The focusChange parameter passed to onAudioFocusChange() indicates the kind of change that's happening. It corresponds to the duration hint used by the app that's acquiring focus. Your app should respond appropriately.

Transient loss of focus

If the focus change is transient (AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK or AUDIOFOCUS_LOSS_TRANSIENT), your app should duck (if you are not relying on automatic ducking) or pause playing but otherwise maintain the same state.

During a transient loss of audio focus, you should continue to monitor changes in audio focus and be prepared to resume normal playback when you regain the focus. When the blocking app abandons focus, you receive a callback (AUDIOFOCUS_GAIN). At this point, you can restore the volume to normal level or restart playback.

Permanent loss of focus

If the audio focus loss is permanent (AUDIOFOCUS_LOSS), another app is playing audio. Your app should pause playback immediately, as it won't ever receive an AUDIOFOCUS_GAIN callback. To restart playback, the user must take an explicit action, like pressing the play transport control in a notification or app UI.

The following code snippet demonstrates how to implement the OnAudioFocusChangeListener and its onAudioFocusChange() callback. Notice the use of a Handler to delay the stop callback on a permanent loss of audio focus.

private val handler = Handler() private val afChangeListener = AudioManager.OnAudioFocusChangeListener { focusChange ->     when (focusChange) {         AudioManager.AUDIOFOCUS_LOSS -> {             // Permanent loss of audio focus             // Pause playback immediately             mediaController.transportControls.pause()             // Wait 30 seconds before stopping playback             handler.postDelayed(delayedStopRunnable, TimeUnit.SECONDS.toMillis(30))         }         AudioManager.AUDIOFOCUS_LOSS_TRANSIENT -> {             // Pause playback         }         AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK -> {             // Lower the volume, keep playing         }         AudioManager.AUDIOFOCUS_GAIN -> {             // Your app has been granted audio focus again             // Raise volume to normal, restart playback if necessary         }     } }

private Handler handler = new Handler(); AudioManager.OnAudioFocusChangeListener afChangeListener =   new AudioManager.OnAudioFocusChangeListener() {     public void onAudioFocusChange(int focusChange) {       if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {         // Permanent loss of audio focus         // Pause playback immediately         mediaController.getTransportControls().pause();         // Wait 30 seconds before stopping playback         handler.postDelayed(delayedStopRunnable,           TimeUnit.SECONDS.toMillis(30));       }       else if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT) {         // Pause playback       } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK) {         // Lower the volume, keep playing       } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {         // Your app has been granted audio focus again         // Raise volume to normal, restart playback if necessary       }     }   };

The handler uses a Runnable that looks like this:

private var delayedStopRunnable = Runnable {     mediaController.transportControls.stop() }

private Runnable delayedStopRunnable = new Runnable() {     @Override     public void run() {         getMediaController().getTransportControls().stop();     } };

To ensure the delayed stop does not kick in if the user restarts playback, call mHandler.removeCallbacks(mDelayedStopRunnable) in response to any state changes. For example, call removeCallbacks() in your Callback's onPlay(), onSkipToNext(), etc. You should also call this method in your service's onDestroy() callback when cleaning up the resources used by your service.