The event MediaPlayer.PlaybackEventListener.onTimedMetadata notifies your application at the first occurrence in the manifest of each tag that matches a subscribed tag name.
/**
* Interface definition of a set of callback to be invoked during playback.
*/
interface PlaybackEventListener extends EventListener {
/**
* Called when a new timed metadata is discovered in the manifest.
* @param timedMetadata the object encapsulating the metadata information,
* such as the relative time, type, tag name and id etc.
*/
void onTimedMetadata(TimedMetadata timedMetadata);
...
}