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 returnsAUDIOFOCUS_REQUEST_GRANTED
. Make the call torequestAudioFocus()
in theonPlay()
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, specifyCONTENT_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()
andabandonAudioFocus()
.
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:
The first, currently playing app meets all of these criteria:
- The app has either the
AudioAttributes.USAGE_MEDIA
orAudioAttributes.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
.
- The app has either the
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:
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)
.
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
orAudioAttributes.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.
Method | Notes |
---|---|
setFocusGain()
|
This field is required in every request. It takes the same values as
the durationHint used in the pre-Android 8.0 call to requestAudioFocus() :
AUDIOFOCUS_GAIN , AUDIOFOCUS_GAIN_TRANSIENT ,
AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK , or AUDIOFOCUS_GAIN_TRANSIENT_EXCLUSIVE .
|
setAudioAttributes()
|
AudioAttributes describes the use case for your app. The
system looks at them when an app gains and loses audio focus. Attributes
supersede the notion of stream type. In Android 8.0 (API level 26) and later,
stream types for any operation other than volume controls are deprecated. Use
the same attributes in the focus request that you use in your audio player (as
shown in the example following this table).
Use an
If not specified, |
setWillPauseWhenDucked()
|
When another app requests focus with
AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK , the app that has focus does not
usually receive an
onAudioFocusChange()
callback because the system can do the
ducking by itself. When you need to pause playback rather
than duck the volume, call setWillPauseWhenDucked(true) and create and set an
OnAudioFocusChangeListener , as described in automatic
ducking.
|
setAcceptsDelayedFocusGain()
|
A request for audio focus can fail when the focus is locked by another app.
This method enables delayed focus gain: the ability
to asynchronously acquire focus when it becomes available.
Note that delayed focus gain only works if you also specify an
|
setOnAudioFocusChangeListener()
|
An OnAudioFocusChangeListener is only required if you also specify
willPauseWhenDucked(true) or setAcceptsDelayedFocusGain(true) in the request.
There are two methods for setting the listener: one with and one without a
handler argument. The handler is the thread on which the listener runs. If you
do not specify a handler, the handler associated with the main
|
The following example shows how to use an AudioFocusRequest.Builder
to build
an AudioFocusRequest
and request and abandon audio focus:
Kotlin
// 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 } } }
Java
// 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.)
Kotlin
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 }
Java
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()
.
Kotlin
audioManager.abandonAudioFocus(afChangeListener)
Java
// 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
orAUDIOFOCUS_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 anAUDIOFOCUS_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.
Kotlin
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 } } }
Java
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:
Kotlin
private var delayedStopRunnable = Runnable { mediaController.transportControls.stop() }
Java
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.