MediaSession
class MediaSession : Closeable
MediaLibraryService.MediaLibrarySession |
This class is deprecated. androidx.media2 is deprecated. |
Allows a media app to expose its transport controls and playback information in a process to other processes including the Android framework and other apps. Common use cases are as follows.
- Bluetooth/wired headset key events support
- Android Auto/Wearable support
- Separating UI process and playback process
A MediaSession should be created when an app wants to publish media playback information or handle media keys. In general an app only needs one session for all playback, though multiple sessions can be created to provide finer grain controls of media. See Supporting Multiple Sessions for detail.
If you want to support background playback, MediaSessionService is preferred instead. With it, your playback can be revived even after playback is finished. See for details.
Topics covered here:
- Session Lifecycle
- Thread
- Media key events mapping
- Supporting Multiple Sessions
- Backward compatibility with legacy session APIs
- Backward compatibility with legacy controller APIs
Session Lifecycle
A session can be obtained by Builder. The owner of the session may pass its session token to other processes to allow them to create a MediaController to interact with the session.
When a session receive transport control commands, the session sends the commands directly to the underlying media player set by Builder or updatePlayer.
When an app is finished performing playback it must call close to clean up the session and notify any controllers. The app is responsible for closing the underlying player after closing the session. is closed.
Thread
MediaSession objects are thread safe, but should be used on the thread on the looper.
Media key events mapping
Here's the table of per key event.
| Key code | API |
|---|---|
KEYCODE_MEDIA_PLAY |
play |
KEYCODE_MEDIA_PAUSE |
pause |
KEYCODE_MEDIA_NEXT |
skipToNextPlaylistItem |
KEYCODE_MEDIA_PREVIOUS |
skipToPreviousPlaylistItem |
KEYCODE_MEDIA_STOP |
pause and then seekTo with 0 |
KEYCODE_MEDIA_FAST_FORWARD |
onFastForward |
KEYCODE_MEDIA_REWIND |
onRewind |
|
Supporting Multiple Sessions
Generally speaking, multiple sessions aren't necessary for most media apps. One exception is if your app can play multiple media content at the same time, but only for the playback of video-only media or remote playback, since audio focus policy recommends not playing multiple audio content at the same time. Also keep in mind that multiple media sessions would make Android Auto and Bluetooth device with display to show your apps multiple times, because they list up media sessions, not media apps.Backward compatibility with legacy session APIs
An activeMediaSessionCompat is internally created with the MediaSession for the backward compatibility. It's used to handle incoming connection and command from . And helps to utilize existing APIs that are built with legacy media session APIs. Use getSessionCompatToken for getting the token for the underlying MediaSessionCompat.
Backward compatibility with legacy controller APIs
In addition to themedia2 controller API, session also supports connection from the legacy controller API - framework controller and AndroidX controller compat. However, ControllerInfo may not be precise for legacy controller. See ControllerInfo for the details.
Unknown package name nor UID doesn't mean that you should disallow connection nor commands. For SDK levels where such issue happen, session tokens could only be obtained by trusted apps (e.g. Bluetooth, Auto, ...), so it may be better for you to allow them as you did with legacy session.
| See also | |
|---|---|
MediaSessionService |
Summary
Nested types |
|---|
class MediaSession.BuilderThis class is deprecated. androidx.media2 is deprecated. |
|
This class is deprecated. androidx.media2 is deprecated. |
|
This class is deprecated. androidx.media2 is deprecated. |
|
This class is deprecated. androidx.media2 is deprecated. |
abstract class MediaSession.SessionCallbackThis class is deprecated. androidx.media2 is deprecated. |
Public functions |
|
|---|---|
Unit |
broadcastCustomCommand(command: SessionCommand, args: Bundle?)Broadcasts a custom command to all connected controllers. |
Unit |
close() |
(Mutable)List<MediaSession.ControllerInfo!> |
Returns the list of connected controller. |
String |
getId()Gets the session ID |
SessionPlayer |
Gets the underlying |
MediaSessionCompat.Token |
Gets the |
SessionToken |
getToken()Returns the |
ListenableFuture<SessionResult!> |
sendCustomCommand(Sends a custom command to a specific controller. |
Unit |
setAllowedCommands(Sets the new allowed command group for the controller. |
ListenableFuture<SessionResult!> |
setCustomLayout(Sets ordered list of |
Unit |
updatePlayer(player: SessionPlayer)Updates the underlying |
Public functions
fun broadcastCustomCommand(command: SessionCommand, args: Bundle?): Unit
Broadcasts a custom command to all connected controllers.
This is synchronous call and doesn't wait for result from the controller. Use sendCustomCommand for getting the result.
A command is not accepted if it is not a custom command.
| Parameters | |
|---|---|
command: SessionCommand |
a command |
args: Bundle? |
optional argument |
| See also | |
|---|---|
sendCustomCommand |
fun getConnectedControllers(): (Mutable)List<MediaSession.ControllerInfo!>
Returns the list of connected controller.
| Returns | |
|---|---|
(Mutable)List<MediaSession.ControllerInfo!> |
list of |
fun getPlayer(): SessionPlayer
Gets the underlying SessionPlayer.
When the session is closed, it returns the lastly set player.
| Returns | |
|---|---|
SessionPlayer |
player. |
fun getSessionCompatToken(): MediaSessionCompat.Token
Gets the MediaSessionCompat.Token for the MediaSessionCompat created internally by this session.
fun sendCustomCommand(
controller: MediaSession.ControllerInfo,
command: SessionCommand,
args: Bundle?
): ListenableFuture<SessionResult!>
Sends a custom command to a specific controller.
A command is not accepted if it is not a custom command.
| Parameters | |
|---|---|
command: SessionCommand |
a command |
args: Bundle? |
optional argument |
| See also | |
|---|---|
broadcastCustomCommand |
fun setAllowedCommands(
controller: MediaSession.ControllerInfo,
commands: SessionCommandGroup
): Unit
Sets the new allowed command group for the controller.
This is synchronous call. Changes in the allowed commands take effect immediately regardless of the controller notified about the change through #onAllowedCommandsChanged(MediaController, SessionCommandGroup)
| Parameters | |
|---|---|
controller: MediaSession.ControllerInfo |
controller to change allowed commands |
commands: SessionCommandGroup |
new allowed commands |
fun setCustomLayout(
controller: MediaSession.ControllerInfo,
layout: (Mutable)List<MediaSession.CommandButton!>
): ListenableFuture<SessionResult!>
Sets ordered list of CommandButton for controllers to build UI with it.
It's up to controller's decision how to represent the layout in its own UI. Here are some examples.
Note: layout[i] means a CommandButton at index i in the given list
| Controller UX layout | Layout example |
|---|---|
| Row with 3 icons | layout[1]layout[0]layout[2] |
| Row with 5 icons | layout[3]layout[1]layout[0]layout[2]layout[4] |
| Row with 5 icons and an overflow icon, and another expandable row with 5 extra icons | layout[3]layout[1]layout[0]layout[2]layout[4] |
layout[3]layout[1]layout[0]layout[2]layout[4] |
This API can be called in the onConnect.
| Parameters | |
|---|---|
controller: MediaSession.ControllerInfo |
controller to specify layout. |
layout: (Mutable)List<MediaSession.CommandButton!> |
ordered list of layout. |
fun updatePlayer(player: SessionPlayer): Unit
Updates the underlying SessionPlayer for this session to dispatch incoming event to.
| Parameters | |
|---|---|
player: SessionPlayer |
a player that handles actual media playback in your app |