playlist object gets created and populated with the tracks found in the <audio>
tag.
This is to give some sort of compatibility for audio tags already present in webpages where you can include this directive.
HTML of the classic audio tag
<audio>
<source src="http://upload.wikimedia.org/wikipedia/en/d/d0/Rick_Astley_-_Never_Gonna_Give_You_Up.ogg" type="audio/ogg">
</audio>
Just by adding the media-player
directive, it will read the source element(s) and instantiate a playlist containing it.
HTML with angular-media-player
<audio player-control="mediaPlayer" playlist="audioPlaylist" media-player>
<source src="http://upload.wikimedia.org/wikipedia/en/d/d0/Rick_Astley_-_Never_Gonna_Give_You_Up.ogg" type="audio/ogg">
</audio>
$scope.audioPlaylist
in the controller
audioPlaylist = [[ audioPlaylist | json ]]