title: Timebar/Seek Buttons are disabled in Exoplayer for some .mkv files and hevc files
body: <p>It works for some mkv files perfectly but for some mkv files it does not show scrubber on time bar and when i try to seek video programmatically it starts from beginning</p>
  <p><img src="https://i.stack.imgur.com/GcAcm.jpg" alt="enter code here" /></p>
  <pre><code>simplexo = ExoPlayer.Builder(this,DefaultRenderersFactory(this)).build()
  val datasource = DefaultDataSourceFactory(this,Util.getUserAgent(this,&quot;app&quot;))
  concatenate = ConcatenatingMediaSource()
  val mediasource = ProgressiveMediaSource.Factory(datasource).createMediaSource(Uri.parse(ok.get(position.toInt()).path))
  concatenate.addMediaSource(mediasource)
      
  playerview.setPlayer(simplexo)
  simplexo.prepare(concatenate)
  
  simplexo.seekTo(position.toInt(),C.TIME_UNSET)
  simplexo.setPlayWhenReady(true)
  </code></pre>