How to set specified TimedTextSource as default?

Question

I'm using MediaPlayElement, and I have set the media source. Now I want to add several Closed Captions, such English, Indo, Simplified Chinese.

I use the following code to add TimedTextSource, and they are all placed in the media player, but how to specify an item as turned on when opening a media?

var timedTextSource = TimedTextSource.CreateFromUri(new Uri(item.url), item.name);
mediaSource.ExternalTimedTextSources.Add(timedTextSource);

Answer 1

You can try using TimedMetadataTracks.SetPresentationMode like this:

// ms: An instance of MediaSource
// mplayer: MediaPlayerElement
// this code is after add the TimedTextSource

var playbackItem = new MediaPlaybackItem(ms);
var player = new MediaPlayer();
player.Source = playbackItem;
player.BufferingStarted += (_s, _e) =>
{
    playbackItem.TimedMetadataTracks.SetPresentationMode(0, TimedMetadataTrackPresentationMode.PlatformPresented);
};
mplayer.SetMediaPlayer(player);

This method is to actively switch the text track when the video starts to buffer.

Best regards.