This service provides:
What content is playing, the activeMediaItem.
Which media source is playing, the activeSource.
Which sourcess are available in the system at this time.
A media source is an app which has registered a
androidx.media), and is able to play content and lets clients browse it.
This service concentrates all information about media currently being played. As only one source at a time can play audio, Android decides which one gets the audio focus. The chosen source is available here as activeSource.
Each media source makes different operations (actions) available at any given time to be performed, or launched, on the media that it is currently being played. Action represents such an action, and availableActions is a list of what actions are presently available.
Browsing through media offered by media sources is possible with a SourceClient. The IVI media service intentionally excludes this functionality to concentrate on the playback state.