title: JWPlayer mp3 Captions in Playlist
body: <p>I'm using <code>JWPlayer v6.8.4616..</code></p>
  
  <p>When i test it with a Single <code>audio/mp3</code> file, with Caption, it works. For example:</p>
  
  <pre><code>&lt;script type='text/javascript'&gt;
      jwplayer("theplayer").setup({
          file: "http://www.example.com/audio1.mp3",
          tracks: [{
              file: "http://www.example.com/audio1.srt"   
          }]
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>The <code>Audio/mp3</code> file is playing along with Caption on it.</p>
  
  <hr>
  
  <p>But when i test with the <code>Playlist</code>, the Captions are <strong>shown only on the Video Tracks</strong>, but not on the Audio/mp3 Tracks.</p>
  
  <p>Like:</p>
  
  <pre><code>&lt;script type='text/javascript'&gt;
      jwplayer("theplayer").setup({
          playlist: [{
              file: "http://www.example.com/video1.mp4",
              title: "Video Track (1)",
              tracks: [{
                  file: "http://www.example.com/video1.srt", 
                  label: "English",
                  kind: "captions",
                  "default": true 
              }]
          },{
              file: "http://www.example.com/video2.mp4",
              title: "Video Track (2)",
              tracks: [{
                  file: "http://www.example.com/video2.srt",
                  label: "English",
                  kind: "captions",
                  "default": true 
              }]
          },{
              file: "http://www.example.com/audio1.mp3",
              title: "Audio Track (1)",
              tracks: [{
                  file: "http://www.example.com/audio1.srt",
                  label: "English",
                  kind: "captions",
                  "default": true 
              }]
          }]
      });
  &lt;/script&gt;
  </code></pre>
  
  <p>Why is it and how to have Captions on the Audio/mp3 Tracks in the Playlist, please?</p>