title: external audio tracks not streaming via hls.js and m3u8
body: <p>I have an mp4 video file that I've converted to <code>.ts</code> file with ffmpeg for streaming via <code>m3u8</code>. along with that mp4 I also have multiple audio files as <code>.wav</code> that are the alternate audio files for the video. I have added them to a main <code>m3u8</code> file like this:</p>
  
  <pre><code>#EXTM3U
  #EXT-X-VERSION:3
  
  #EXT-X-STREAM-INF:BANDWIDTH=850000,RESOLUTION=640x360,AUDIO="bipbop_audio"
  index0.m3u8
  
  #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="bipbop_audio",LANGUAGE="eng",NAME="BipBop Audio 1",
   AUTOSELECT=YES,DEFAULT=YES
  #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="bipbop_audio",LANGUAGE="nr",NAME="BipBop Audio 2",
   AUTOSELECT=NO,DEFAULT=NO,URI="audio1.m3u8"
  </code></pre>
  
  <p>when I go to play this using hls.js in the browser the video file's <code>m3u8</code> is downloaded (index0.m3u8) and the video plays, but the audio file's <code>m3u8</code> files are not downloaded by the browser and the audio does not play. I can actually see the alternate audio info in the hls.js object instance that is in the main <code>m3u8</code> file when I console log it, but making hls.js switch to it does not make it download nor play.</p>
  
  <p>So far I've tried:</p>
  
  <ol>
  <li>converting the audio to <code>.mp3</code> via ffmpeg</li>
  <li>converting the audio to <code>.ts</code> via ffmpeg</li>
  </ol>
  
  <p>here is what the <code>.ts</code> version of the audio file looks like as an <code>m3u8</code></p>
  
  <pre><code>#EXTM3U
  #EXT-X-VERSION:3
  #EXT-X-TARGETDURATION:2914
  #EXT-X-MEDIA-SEQUENCE:0
  #EXTINF:2913.661333,
  abc0.ts
  #EXT-X-ENDLIST
  </code></pre>
  
  <p>I'm pretty new to ffmpeg and hls.js, but is there some specific way I need to make ffmpeg generate the <code>m3u8</code> files for both the audio and video to make them work together?
  so far I don't see any errors in the browser relating to the main <code>m3u8</code> or hls.js.</p>