looperSample.kt

class AudiTrackOutput(private val audioBuffer: AudioDataBuffer) : Thread() {

    private lateinit var handler: Handler
    
    fun play(from: Int) {
        handler.removeCallbacksAndMessages(null)
        val msg = handler.obtainMessage()
        val bundle = Bundle()
        bundle.putInt("FROM", from)
        msg.data = bundle
        handler.sendMessage(Message())
    }

    private val player = AudioTrack(
        AudioAttributes.Builder()
            .setUsage(AudioAttributes.USAGE_MEDIA)
            .setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
            .build(),
        AudioFormat.Builder()
            .setSampleRate(SAMPLING_RATE)
            .setEncoding(AudioFormat.ENCODING_PCM_16BIT)
            .setChannelMask(AudioFormat.CHANNEL_OUT_MONO).build(),
        playbackBufferSize,
        AudioTrack.MODE_STREAM,
        AudioManager.AUDIO_SESSION_ID_GENERATE
    )

    init {
        player.play()
    }

    override fun run() {
        Looper.prepare()

        handler = Handler { msg ->
            val bundle: Bundle = msg.data
            val from = bundle.getInt("FROM")
            audioBuffer.read(from).also {
                while (it.isNotEmpty()) {
                    player.write(it.removeAt(0), 0, BUFFER_SIZE)
                }
            }
            true
        }

        Looper.loop()
    }
}