title: Trying to work with ExoPlayer - lots of unknowns
body: <p>There is no mention on the internet what on earth is a userAgent, what do I pass as its value and what is it used for. No documentation, nothing.
  Also, how do I obtain "videoRepresentations" and what is it?</p>
  
  <p><img src="https://i.stack.imgur.com/gqiea.png" alt="enter image description here"></p>
  
  <pre><code>    // Build the video renderer.
      DataSource videoDataSource = new HttpDataSource(userAgent, HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
      ChunkSource videoChunkSource = new DashChunkSource(videoDataSource, new AdaptiveEvaluator(bandwidthMeter), videoRepresentations);
      ChunkSampleSource videoSampleSource = new ChunkSampleSource(videoChunkSource, loadControl, VIDEO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
      MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(videoSampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 0, mainHandler, playerActivity, 50);
  
      // Build the audio renderer.
      DataSource audioDataSource = new HttpDataSource(userAgent, HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
      ChunkSource audioChunkSource = new DashChunkSource(audioDataSource, new FormatEvaluator.FixedEvaluator(), audioRepresentation);
      SampleSource audioSampleSource = new ChunkSampleSource(audioChunkSource, loadControl, AUDIO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
      MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(audioSampleSource, null, true);
  </code></pre>
  
  <p>Documentation is extremely insufficient
  <a href="http://developer.android.com/guide/topics/media/exoplayer.html" rel="nofollow noreferrer">http://developer.android.com/guide/topics/media/exoplayer.html</a> </p>