title: Exoplayer can't load subtitles of HLS video
body: <p>Here is my m3u8 with subtitles embedded:</p>
  
  <pre><code>#EXTM3U
  
  
  #EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="Vietnamses",DEFAULT=NO,AUTOSELECT=YES,FORCED=NO,LANGUAGE="vi",CHARACTERISTICS="public.accessibility.transcribes-spoken-dialog, public.accessibility.describes-music-and-sound",URI="http://api.mhdviet.vn/sub.m3u8?language=VIE&amp;movieid=8220&amp;ep=1"
  #EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="Vietnamses (FORCED)",DEFAULT=NO,AUTOSELECT=YES,FORCED=YES,LANGUAGE="vi",URI="http://api.mhdviet.vn/sub.m3u8?language=VIE&amp;movieid=8220&amp;ep=1"
  #EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="English",DEFAULT=NO,AUTOSELECT=YES,FORCED=NO,LANGUAGE="eng",CHARACTERISTICS="public.accessibility.transcribes-spoken-dialog, public.accessibility.describes-music-and-sound",URI="http://api.mhdviet.vn/sub.m3u8?language=ENG&amp;movieid=8220&amp;ep=1"
  #EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",NAME="English (FORCED)",DEFAULT=NO,AUTOSELECT=YES,FORCED=YES,LANGUAGE="eng",URI="http://api.mhdviet.vn/sub.m3u8?language=ENG&amp;movieid=8220&amp;ep=1"
  
  #EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=855040,RESOLUTION=480x352,SUBTITLES="subs"
  http://allvarhsin.flix-cdn.com/FlixVOD/ACompany/I_Frankenstein_2014/1f9daf14d2f84cd8cd0121804ec1e35a/480/480.m3u8
  </code></pre>
  
  <p>I used <code>Exoplayer</code> to load my hls video. <strong>What is wrong with my m3u8 file?</strong></p>