Allow the user to change the track

Here is an example of how a user can select a closed-caption track.

1. To display the available closed caption tracks, use the MediaPlayerItem.closedCaptionsTracks property.

   var tracks = item.closedCaptionsTracks;
   

2. To set which closed-caption track is current, use the MediaPlayerItem.selectClosedCaptionsTrack method.

3. After the media player item is prepared, retrieve it from the media player by using the MediaPlayer. currentItem method.

   // Select the cc track with index k. 
   var item = mediaPlayer.currentItem;     
   var tracks = item.closedCaptionsTracks; 
    
   if (k >= 0 && k < tracks.length) { 
       item.selectClosedCaptionsTrack(tracks[k]); 
   }