| MediaDescriptionCompat | A simple set of metadata for a media item suitable for display. | 
| MediaDescriptionCompat.Builder | 
          Builder for MediaDescriptionCompat objects. 
          
    
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| MediaDescriptionCompatApi21 | |
| MediaDescriptionCompatApi21.Builder | |
| MediaMetadataCompat | Contains metadata about an item, such as the title, artist, etc. | 
| MediaMetadataCompat.Builder | Use to build MediaMetadata objects. | 
| RatingCompat | A class to encapsulate rating information used as content metadata. | 
| TransportController | Base interface to controlling a media transport. | 
| TransportMediator | Helper for implementing a media transport control (with play, pause, skip, and other media actions). | 
| TransportPerformer | Implemented by the playback side of the media system, to respond to requests to perform actions and to retrieve its current state. | 
| TransportStateListener | 
          A listener for playback changes that can be registered with
 TransportController. 
          
    
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| VolumeProviderCompat | Handles requests to adjust or set the volume on a session. | 
| VolumeProviderCompat.Callback | Listens for changes to the volume. |