MediaSession

Added in 1.0.0
Deprecated in 1.3.0

class MediaSession : Closeable

Known direct subclasses
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:

  1. Session Lifecycle
  2. Thread
  3. Media key events mapping
  4. Supporting Multiple Sessions
  5. Backward compatibility with legacy session APIs
  6. 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 active MediaSessionCompat 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 the media2 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.

Summary

Nested types

This 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.

This class is deprecated.

androidx.media2 is deprecated.

Public functions

Unit

Broadcasts a custom command to all connected controllers.

Unit
(Mutable)List<MediaSession.ControllerInfo!>

Returns the list of connected controller.

String

Gets the session ID

SessionPlayer

Gets the underlying SessionPlayer.

MediaSessionCompat.Token

Gets the MediaSessionCompat.Token for the MediaSessionCompat created internally by this session.

SessionToken

Returns the SessionToken for creating MediaController.

ListenableFuture<SessionResult!>
sendCustomCommand(
    controller: MediaSession.ControllerInfo,
    command: SessionCommand,
    args: Bundle?
)

Sends a custom command to a specific controller.

Unit
setAllowedCommands(
    controller: MediaSession.ControllerInfo,
    commands: SessionCommandGroup
)

Sets the new allowed command group for the controller.

ListenableFuture<SessionResult!>

Sets ordered list of CommandButton for controllers to build UI with it.

Unit

Updates the underlying SessionPlayer for this session to dispatch incoming event to.

Public functions

broadcastCustomCommand

Added in 1.0.0
Deprecated in 1.3.0
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

close

Added in 1.0.0
Deprecated in 1.3.0
fun close(): Unit

getConnectedControllers

Added in 1.0.0
Deprecated in 1.3.0
fun getConnectedControllers(): (Mutable)List<MediaSession.ControllerInfo!>

Returns the list of connected controller.

getId

Added in 1.0.0
Deprecated in 1.3.0
fun getId(): String

Gets the session ID

Returns
String

getPlayer

Added in 1.0.0
Deprecated in 1.3.0
fun getPlayer(): SessionPlayer

Gets the underlying SessionPlayer.

When the session is closed, it returns the lastly set player.

Returns
SessionPlayer

player.

getSessionCompatToken

Added in 1.1.0
Deprecated in 1.3.0
fun getSessionCompatToken(): MediaSessionCompat.Token

Gets the MediaSessionCompat.Token for the MediaSessionCompat created internally by this session.

getToken

Added in 1.0.0
Deprecated in 1.3.0
fun getToken(): SessionToken

Returns the SessionToken for creating MediaController.

sendCustomCommand

Added in 1.0.0
Deprecated in 1.3.0
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

setAllowedCommands

Added in 1.0.0
Deprecated in 1.3.0
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

setCustomLayout

Added in 1.0.0
Deprecated in 1.3.0
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.

updatePlayer

Added in 1.0.0
Deprecated in 1.3.0
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