title: ExoPlayer - play local mp4 file in SD card
body: <p>I am using the Exoplayer Demo app and want to preload a MP4 video from SD card. 
  I have tried out the implementation from <a href="https://stackoverflow.com/questions/28648997/exoplayer-how-to-play-local-mp3-file">this post</a>, but it does not work. There is no such class called DemoUtil.java in my exoplayer Demo.
  Instead used:</p>
  
  <pre><code>public static final Sample[] LOCAL_VIDEOS = new Sample[] {
  new Sample("Some User friendly name of video 1",
  "/mnt/sdcard/video1.mp4", Util.TYPE_OTHER),
  };
  </code></pre>
  
  <p>I also  could not use the their snippet of code mentioned for SampleChooserActivity.java. (Kept giving me errors)</p>
  
  <p>I instead used :</p>
  
  <pre><code>group = new SampleGroup("Local Videos");
  group.addAll(Samples.LOCAL_VIDEOS);
  sampleGroups.add(group);
  </code></pre>
  
  <p>What am I doing wrong? Does the path of the file change for every device?</p>