Android: play /raw resource with Exoplayer

exowrapper.kt

val player = ExoPlayerFactory.newSimpleInstance(context, DefaultTrackSelector())

val rawDataSource = RawResourceDataSource(context)
// open the /raw resource file
rawDataSource.open(DataSpec(RawResourceDataSource.buildRawResourceUri(R.raw.brown)))

// create a media source with the raw DataSource
val mediaSource = ExtractorMediaSource.Factory(DataSource.Factory { rawDataSource })
        .createMediaSource(rawDataSource.uri)

// play immediately if true
player.playWhenReady = true
// setup the player using the source 
player.prepare(mediaSource)