AudioInputStream and AudioOutputStream for Android. These wrap AudioRecord and AudioTrack.

AudioInputStream.kt

import android.media.AudioFormat
import android.media.AudioRecord
import android.media.MediaRecorder
import java.io.IOException
import java.io.InputStream

class AudioInputStream(
        audioSource: Int = MediaRecorder.AudioSource.DEFAULT,
        sampleRate: Int = 44100,
        channelConfig: Int = AudioFormat.CHANNEL_IN_MONO,
        audioFormat: Int = AudioFormat.ENCODING_PCM_8BIT,
        bufferSizeInBytes: Int = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat)) : InputStream() {

    private val audioRecord = AudioRecord(audioSource, sampleRate, channelConfig, audioFormat, bufferSizeInBytes).apply {
        startRecording()
    }

    @Deprecated("Use read(audioData, offset, length)")
    @Throws(IOException::class)
    override fun read(): Int {
        val tmp = byteArrayOf(0)
        read(tmp, 0, 1)
        return tmp[0].toInt()
    }

    @Throws(IOException::class)
    override fun read(audioData: ByteArray, offset: Int, length: Int): Int {
        try {
            return audioRecord.read(audioData, offset, length)
        } catch (e: Exception) {
            throw IOException(e)
        }
    }

    override fun close() {
        audioRecord.stop()
        audioRecord.release()
        super.close()
    }
}

AudioOutputStream.kt

import android.media.AudioFormat
import android.media.AudioManager
import android.media.AudioTrack
import java.io.IOException
import java.io.OutputStream

class AudioOutputStream(
        streamType: Int = AudioManager.STREAM_MUSIC,
        sampleRate: Int = 44100,
        channelConfig: Int = AudioFormat.CHANNEL_OUT_MONO,
        audioFormat: Int = AudioFormat.ENCODING_PCM_8BIT,
        bufferSizeInBytes: Int = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat)) : OutputStream() {

    private val audioTrack = AudioTrack(streamType, sampleRate, channelConfig, audioFormat, bufferSizeInBytes, AudioTrack.MODE_STREAM).apply {
        play()
    }

    @Deprecated("Use write(audioData, offset, length)")
    @Throws(IOException::class)
    override fun write(b: Int) {
        val tmp = byteArrayOf(0)
        tmp[0] = b.toByte()
        write(tmp, 0, 1)
    }

    @Throws(IOException::class)
    override fun write(audioData: ByteArray, offset: Int, length: Int) {
        try {
            audioTrack.write(audioData, offset, length)
        } catch (e: Exception) {
            throw IOException(e)
        }
    }

    override fun close() {
        audioTrack.stop()
        audioTrack.release()
        super.close()
    }
}

Thanks a lot