This type is used by AvMediaPlayer to show current media info.
duration == 0 means the media is realtime stream.
tracks contains all the tracks of the media. The key is the track id. However, video tracks may not available on ios/macos/windows.
This type is used by MediaInfo to show information about a track.
Only type is guaranteed to be non-null. Other information may not be available and can be different on different platforms.
