Uri uri = Uri
          .fromFile(new File(Environment.getExternalStorageDirectory() + "/testXor.mp5"));

mediaSource = createResolverMediaSourceFactory().createMediaSource(uri);

private ProgressiveMediaSource.Factory createResolverMediaSourceFactory() {
    final MyDataSource inputStreamDataSource = new MyDataSource(this);
    DataSource.Factory factory = () -> inputStreamDataSource;

    return new ProgressiveMediaSource.Factory(
        new ResolvingDataSource.Factory(factory, new MyResolver(16, 1692377)));
  }