1.3.0-rc01

This release includes the following changes since the 1.3.0-beta01 release:

• ExoPlayer:
  • Add source prefix to all Format.id fields generated from MergingMediaSource. This helps to identify which source produced a Format (#883).
  • Fix the regex used for validating custom Common Media Client Data (CMCD) key names by modifying it to only check for hyphen (#1028).
  • Stop double-encoding CMCD query parameters (#1075).
• Audio:
  • Improve silence skipping algorithm with smooth volume ramp; retained minimal silence and more natural silence durations (#7423).
  • Report the skipped silence more deterministically (#1035).
• Session:
  • Fix issue where MediaItem.RequestMetadata with just non-null extras is not transmitted between media controllers and sessions.
  • Add constructor to MediaLibrarySession.Builder that only takes a Context instead of a MediaLibraryService.
• HLS Extension:
  • Resolve seeks to beginning of a segment more efficiently (#1031).