Add rating to media session metadata

Feature requests
1

Feature description:

Expose the user rating for music for the playing media session metadata. (Maybe as METADATA_KEY_USER_RATING or METADATA_KEY_RATING?)

Problem solved:

I’m building a custom app that reads the current playing media session information, and relays it to my server to be shown on other devices. The app gets the notification permission, and find the playing MediaController to acquire the current playing music info.

Currently I can get the album name/art/artist/title/durations, but I can’t find any user rating (and MediaController.getRatingType also returns Rating.RATING_NONE now)

Brought benefits:

More complete info can be acquired by apps that utilize the MediaController / MediaSession API in Android.

I’m not sure if there’s any other existing app that utilize it other than my custom app I’m building, but it’d be appreciate to see this added.

Other application solutions:

Additional description and context:

Here’s a sample dump for the MediaMetadata I’m getting from the MediaController.getMetadata API now from Symfonium Version 13.6.0B1 (127599), the provider is Subsonic:

metadata = MediaMetadata:
  [String] android.media.metadata.ALBUM = "天空カフェテリア"
  [Bitmap] android.media.metadata.ALBUM_ART = 780x774 (config=ARGB_8888)
  [String] android.media.metadata.ALBUM_ARTIST = "Various Artists"
  [String] android.media.metadata.ARTIST = "Petit Rabbit's"
  [String] android.media.metadata.COMPOSER = ""
  [String] android.media.metadata.DISPLAY_DESCRIPTION = "天空カフェテリア"
  [String] android.media.metadata.DISPLAY_SUBTITLE = "Petit Rabbit's"
  [String] android.media.metadata.DISPLAY_TITLE = "天空カフェテリア"
  [Long]   android.media.metadata.DURATION = 222000
  [String] android.media.metadata.GENRE = ""
  [String] android.media.metadata.MEDIA_ID = "current_playlist/76"
  [String] android.media.metadata.TITLE = "天空カフェテリア"

Screenshots / Mockup: