how to record .wav format file in android

Question

I would like to record .wav files using android. is there any way to do this?

Answer 1

After a quick google I found out that there is a direct support for wave recording. Most common wave format is PCM. The android.media.AudioRecord supports PCM output. You only need to write this to a file then.

• AudioRecord

After the file you then create you must program your own convertor to wave (or look for an online library for that).

If you like an app that is ready to go and record in wave you can download this app:

• uk.ac.cam.cl.dtg.android.audionetworking.hertz

Extra link:

• Subject: [android-developers] Re: How to record audio in WAV format?

Answer 2

There are two classes that can record audio, AudioRecord and MediaRecorder.

• http://developer.android.com/reference/android/media/MediaRecorder.html
• http://developer.android.com/reference/android/media/AudioRecord.html

I also write an application right now, that is recording and showing the frequency spectrogram. So I use AudioRecord class

good luck!

Answer 3

You have to use AudioRecord class and write the wav header data by yourself. This code should include all you need.

WavRecorder(val context: Context) {
    private var recorder: AudioRecord? = null
    private var isRecording = false

    private var recordingThread: Thread? = null

    fun startRecording(_filename: String? = null, internalStorage: Boolean = false) {
        val filename = _filename ?: "recording-${System.currentTimeMillis()}.wav"

        val path = if (internalStorage) context.filesDir?.path + "/$filename"
        else context.externalCacheDir?.path + "/$filename"

        recorder = AudioRecord(MediaRecorder.AudioSource.MIC,
                RECORDER_SAMPLE_RATE, RECORDER_CHANNELS,
                RECORDER_AUDIO_ENCODING, 512)

        recorder?.startRecording()
        isRecording = true

        recordingThread = thread(true) {
            writeAudioDataToFile(path)
        }
    }


    fun stopRecording() {
        recorder?.run {
            isRecording = false;
            stop()
            release()
            recordingThread = null
            recorder = null
        }
    }

    private fun short2byte(sData: ShortArray): ByteArray {
        val arrSize = sData.size
        val bytes = ByteArray(arrSize * 2)
        for (i in 0 until arrSize) {
            bytes[i * 2] = (sData[i] and 0x00FF).toByte()
            bytes[i * 2 + 1] = (sData[i].toInt() shr 8).toByte()
            sData[i] = 0
        }
        return bytes
    }

    private fun writeAudioDataToFile(path: String) {
        val sData = ShortArray(BufferElements2Rec)
        var os: FileOutputStream? = null
        try {
            os = FileOutputStream(path)
        } catch (e: FileNotFoundException) {
            e.printStackTrace()
        }

        val data = arrayListOf<Byte>()

        for (byte in wavFileHeader()) {
            data.add(byte)
        }

        while (isRecording) {
            // gets the voice output from microphone to byte format
            recorder?.read(sData, 0, BufferElements2Rec)
            try {
                val bData = short2byte(sData)
                for (byte in bData)
                    data.add(byte)
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }

        updateHeaderInformation(data)

        os?.write(data.toByteArray())

        try {
            os?.close()
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }


    /**
     * Constructs header for wav file format
     */
    private fun wavFileHeader(): ByteArray {
        val headerSize = 44
        val header = ByteArray(headerSize)

        header[0] = 'R'.toByte() // RIFF/WAVE header
        header[1] = 'I'.toByte()
        header[2] = 'F'.toByte()
        header[3] = 'F'.toByte()

        header[4] = (0 and 0xff).toByte() // Size of the overall file, 0 because unknown
        header[5] = (0 shr 8 and 0xff).toByte()
        header[6] = (0 shr 16 and 0xff).toByte()
        header[7] = (0 shr 24 and 0xff).toByte()

        header[8] = 'W'.toByte()
        header[9] = 'A'.toByte()
        header[10] = 'V'.toByte()
        header[11] = 'E'.toByte()

        header[12] = 'f'.toByte() // 'fmt ' chunk
        header[13] = 'm'.toByte()
        header[14] = 't'.toByte()
        header[15] = ' '.toByte()

        header[16] = 16 // Length of format data
        header[17] = 0
        header[18] = 0
        header[19] = 0

        header[20] = 1 // Type of format (1 is PCM)
        header[21] = 0

        header[22] = NUMBER_CHANNELS.toByte()
        header[23] = 0

        header[24] = (RECORDER_SAMPLE_RATE and 0xff).toByte() // Sampling rate
        header[25] = (RECORDER_SAMPLE_RATE shr 8 and 0xff).toByte()
        header[26] = (RECORDER_SAMPLE_RATE shr 16 and 0xff).toByte()
        header[27] = (RECORDER_SAMPLE_RATE shr 24 and 0xff).toByte()

        header[28] = (BYTE_RATE and 0xff).toByte() // Byte rate = (Sample Rate * BitsPerSample * Channels) / 8
        header[29] = (BYTE_RATE shr 8 and 0xff).toByte()
        header[30] = (BYTE_RATE shr 16 and 0xff).toByte()
        header[31] = (BYTE_RATE shr 24 and 0xff).toByte()

        header[32] = (NUMBER_CHANNELS * BITS_PER_SAMPLE / 8).toByte() //  16 Bits stereo
        header[33] = 0

        header[34] = BITS_PER_SAMPLE.toByte() // Bits per sample
        header[35] = 0

        header[36] = 'd'.toByte()
        header[37] = 'a'.toByte()
        header[38] = 't'.toByte()
        header[39] = 'a'.toByte()

        header[40] = (0 and 0xff).toByte() // Size of the data section.
        header[41] = (0 shr 8 and 0xff).toByte()
        header[42] = (0 shr 16 and 0xff).toByte()
        header[43] = (0 shr 24 and 0xff).toByte()

        return header
    }

    private fun updateHeaderInformation(data: ArrayList<Byte>) {
        val fileSize = data.size
        val contentSize = fileSize - 44

        data[4] = (fileSize and 0xff).toByte() // Size of the overall file
        data[5] = (fileSize shr 8 and 0xff).toByte()
        data[6] = (fileSize shr 16 and 0xff).toByte()
        data[7] = (fileSize shr 24 and 0xff).toByte()

        data[40] = (contentSize and 0xff).toByte() // Size of the data section.
        data[41] = (contentSize shr 8 and 0xff).toByte()
        data[42] = (contentSize shr 16 and 0xff).toByte()
        data[43] = (contentSize shr 24 and 0xff).toByte()
    }

    companion object {
        const val RECORDER_SAMPLE_RATE = 8000
        const val RECORDER_CHANNELS: Int = android.media.AudioFormat.CHANNEL_IN_MONO
        const val RECORDER_AUDIO_ENCODING: Int = android.media.AudioFormat.ENCODING_PCM_16BIT
        const val BITS_PER_SAMPLE: Short = 16
        const val NUMBER_CHANNELS: Short = 1
        const val BYTE_RATE = RECORDER_SAMPLE_RATE * NUMBER_CHANNELS * 16 / 8

        var BufferElements2Rec = 1024
    }
}

Answer 4

I have recently made library for this recording purpose. you just have to do this :-

recorder = OmRecorder.wav(
new PullTransport.Default(mic(), new PullTransport.OnAudioChunkPulledListener() {
    @Override public void onAudioChunkPulled(AudioChunk audioChunk) {
      animateVoice((float) (audioChunk.maxAmplitude() / 200.0));
    }
  }), file());

You can set frequency audio source, etc. and then can record wav file easily. you can find more info on this :-

https://github.com/kailash09dabhi/OmRecorder