PCM -> AAC (Encoder) -> PCM(Decoder) in real-time with correct optimization

Question

I\'m trying to implement

AudioRecord (MIC) ->

PCM -> AAC Encoder
AAC -> PCM Decode

-> AudioTrack??  (SPEAKER)

with Me

Answer 1

I have tried the above code and it didn't work properly.I was getting lot of silence injected to the decoded output. Issue was not setting proper "csd" value to the decoder.

So if you see "silence" in log or Decoder throwing error make sure you have added the following to your media decoder format

int profile = 2;  //AAC LC
int freqIdx = 11;  //8KHz
int chanCfg = 1;  //Mono

ByteBuffer csd = ByteBuffer.allocate(2);
csd.put(0, (byte) (profile << 3 | freqIdx >> 1));
csd.put(1, (byte)((freqIdx & 0x01) << 7 | chanCfg << 3));
mediaFormat.setByteBuffer("csd-0", csd);

Answer 2

After testing this is what I came up with from modifying your code:

 package com.example.app;

    import android.app.Activity;

    import android.media.AudioManager;
    import android.media.MediaCodecInfo;
    import android.media.MediaFormat;
    import android.os.Bundle;

    import android.media.AudioFormat;
    import android.media.AudioRecord;
    import android.media.AudioTrack;
    import android.media.MediaCodec;

    import android.media.MediaRecorder.AudioSource;

    import android.util.Log;

    import java.io.IOException;
    import java.net.DatagramPacket;
    import java.net.DatagramSocket;
    import java.net.InetAddress;
    import java.net.SocketAddress;
    import java.net.SocketException;
    import java.nio.ByteBuffer;

    public class MainActivity extends Activity
    {
        private AudioRecord recorder;
        private AudioTrack player;

        private MediaCodec encoder;
        private MediaCodec decoder;

        private short audioFormat = AudioFormat.ENCODING_PCM_16BIT;
        private short channelConfig = AudioFormat.CHANNEL_IN_MONO;

        private int bufferSize;
        private boolean isRecording;
        private boolean isPlaying;

        private Thread IOrecorder;

        private Thread IOudpPlayer;


        private DatagramSocket ds;
        private final int localPort = 39000;

        @Override
        protected void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            IOrecorder = new Thread(new Runnable()
            {
                public void run()
                {
                    int read;
                    byte[] buffer1 = new byte[bufferSize];

                    ByteBuffer[] inputBuffers;
                    ByteBuffer[] outputBuffers;

                    ByteBuffer inputBuffer;
                    ByteBuffer outputBuffer;

                    MediaCodec.BufferInfo bufferInfo;
                    int inputBufferIndex;
                    int outputBufferIndex;

                    byte[] outData;

                    DatagramPacket packet;
                    try
                    {
                        encoder.start();
                        recorder.startRecording();
                        isRecording = true;
                        while (isRecording)
                        {
                            read = recorder.read(buffer1, 0, bufferSize);
                           // Log.d("AudioRecoder", read + " bytes read");
                            //------------------------

                            inputBuffers = encoder.getInputBuffers();
                            outputBuffers = encoder.getOutputBuffers();
                            inputBufferIndex = encoder.dequeueInputBuffer(-1);
                            if (inputBufferIndex >= 0)
                            {
                                inputBuffer = inputBuffers[inputBufferIndex];
                                inputBuffer.clear();

                                inputBuffer.put(buffer1);

                                encoder.queueInputBuffer(inputBufferIndex, 0, buffer1.length, 0, 0);
                            }

                            bufferInfo = new MediaCodec.BufferInfo();
                            outputBufferIndex = encoder.dequeueOutputBuffer(bufferInfo, 0);



                            while (outputBufferIndex >= 0)
                            {
                                outputBuffer = outputBuffers[outputBufferIndex];

                                outputBuffer.position(bufferInfo.offset);
                                outputBuffer.limit(bufferInfo.offset + bufferInfo.size);

                                outData = new byte[bufferInfo.size];
                                outputBuffer.get(outData);


                               // Log.d("AudioEncoder ", outData.length + " bytes encoded");
                                //-------------
                                packet = new DatagramPacket(outData, outData.length,
                                        InetAddress.getByName("127.0.0.1"), localPort);
                                ds.send(packet);
                                //------------

                                encoder.releaseOutputBuffer(outputBufferIndex, false);
                                outputBufferIndex = encoder.dequeueOutputBuffer(bufferInfo, 0);

                            }
                            // ----------------------;

                        }
                        encoder.stop();
                        recorder.stop();
                    }
                    catch (Exception e)
                    {
                        e.printStackTrace();
                    }
                }
            });



            IOudpPlayer = new Thread(new Runnable()
            {
                public void run()
                {
                    SocketAddress sockAddress;
                    String address;

                    int len = 2048
                    byte[] buffer2 = new byte[len];
                    DatagramPacket packet;

                    byte[] data;

                    ByteBuffer[] inputBuffers;
                    ByteBuffer[] outputBuffers;

                    ByteBuffer inputBuffer;
                    ByteBuffer outputBuffer;

                    MediaCodec.BufferInfo bufferInfo;
                    int inputBufferIndex;
                    int outputBufferIndex;
                    byte[] outData;
                    try
                    {
                        player.play();
                        decoder.start();
                        isPlaying = true;
                        while (isPlaying)
                        {
                            try
                            {
                                packet = new DatagramPacket(buffer2, len);
                                ds.receive(packet);

                                sockAddress = packet.getSocketAddress();
                                address = sockAddress.toString();

                             //   Log.d("UDP Receiver"," received !!! from " + address);

                                data = new byte[packet.getLength()];
                                System.arraycopy(packet.getData(), packet.getOffset(), data, 0, packet.getLength());

                               // Log.d("UDP Receiver",  data.length + " bytes received");

                                //===========
                                inputBuffers = decoder.getInputBuffers();
                                outputBuffers = decoder.getOutputBuffers();
                                inputBufferIndex = decoder.dequeueInputBuffer(-1);
                                if (inputBufferIndex >= 0)
                                {
                                    inputBuffer = inputBuffers[inputBufferIndex];
                                    inputBuffer.clear();

                                    inputBuffer.put(data);

                                    decoder.queueInputBuffer(inputBufferIndex, 0, data.length, 0, 0);
                                }

                                bufferInfo = new MediaCodec.BufferInfo();
                                outputBufferIndex = decoder.dequeueOutputBuffer(bufferInfo, 0);

                                while (outputBufferIndex >= 0)
                                {
                                    outputBuffer = outputBuffers[outputBufferIndex];

                                    outputBuffer.position(bufferInfo.offset);
                                    outputBuffer.limit(bufferInfo.offset + bufferInfo.size);

                                    outData = new byte[bufferInfo.size];
                                    outputBuffer.get(outData);

                                  //  Log.d("AudioDecoder", outData.length + " bytes decoded");

                                    player.write(outData, 0, outData.length);

                                    decoder.releaseOutputBuffer(outputBufferIndex, false);
                                    outputBufferIndex = decoder.dequeueOutputBuffer(bufferInfo, 0..

Answer 3

Your networking code is combining data. You got 369 bytes of compressed data, but on the receiving end you ended up with 1024 bytes. Those 1024 bytes consist of two whole and one partial frame. The two whole frames each decode to 4096 bytes again, for the total of 8192 bytes that you saw. The remaining partial frame will probably be decoded once you send sufficiently more data to the decoder, but you should generally send only whole frames to the decoder.

In addition, MediaCodec.dequeueOutputBuffer() does not only return (positive) buffer indices, but also (negative) status codes. One of the possible codes is MediaCodec.INFO_OUTPUT_FORMAT_CHANGED, which indicates that you need to call MediaCodec.getOutputFormat() to get the format of the audio data. You might see the codec output stereo even if the input was mono. The code you posted simply breaks out of the loop when it receives one of these status codes.

Answer 4

D/AudioRecoder﹕ 4096 bytes read D/AudioEncoder﹕ 360 bytes encoded D/UDP Receiver﹕ received !!! from /127.0.0.1:39000 D/UDP Receiver﹕ 360 bytes received D/AudioDecoder﹕ 8192 bytes decoded

This is because acc decoder always decode to stereo channels,even if the encoded data is MONO. so if your encoding side is set to stereo channels, it will be like:

D/AudioRecoder﹕ 8192 bytes read D/AudioEncoder﹕ 360 bytes encoded D/UDP Receiver﹕ received !!! from /127.0.0.1:39000 D/UDP Receiver﹕ 360 bytes received D/AudioDecoder﹕ 8192 bytes decoded

Answer 5

Self Answer, here's my best effort so far

package com.example.app;

import android.app.Activity;

import android.media.AudioManager;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.os.Bundle;

import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaCodec;

import android.media.MediaRecorder.AudioSource;

import android.util.Log;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketAddress;
import java.net.SocketException;
import java.nio.ByteBuffer;

public class MainActivity extends Activity
{
    private AudioRecord recorder;
    private AudioTrack player;

    private MediaCodec encoder;
    private MediaCodec decoder;

    private short audioFormat = AudioFormat.ENCODING_PCM_16BIT;
    private short channelConfig = AudioFormat.CHANNEL_IN_MONO;

    private int bufferSize;
    private boolean isRecording;
    private boolean isPlaying;

    private Thread IOrecorder;

    private Thread IOudpPlayer;


    private DatagramSocket ds;
    private final int localPort = 39000;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        IOrecorder = new Thread(new Runnable()
        {
            public void run()
            {
                int read;
                byte[] buffer1 = new byte[bufferSize];

                ByteBuffer[] inputBuffers;
                ByteBuffer[] outputBuffers;

                ByteBuffer inputBuffer;
                ByteBuffer outputBuffer;

                MediaCodec.BufferInfo bufferInfo;
                int inputBufferIndex;
                int outputBufferIndex;

                byte[] outData;

                DatagramPacket packet;
                try
                {
                    encoder.start();
                    recorder.startRecording();
                    isRecording = true;
                    while (isRecording)
                    {
                        read = recorder.read(buffer1, 0, bufferSize);
                       // Log.d("AudioRecoder", read + " bytes read");
                        //------------------------

                        inputBuffers = encoder.getInputBuffers();
                        outputBuffers = encoder.getOutputBuffers();
                        inputBufferIndex = encoder.dequeueInputBuffer(-1);
                        if (inputBufferIndex >= 0)
                        {
                            inputBuffer = inputBuffers[inputBufferIndex];
                            inputBuffer.clear();

                            inputBuffer.put(buffer1);

                            encoder.queueInputBuffer(inputBufferIndex, 0, buffer1.length, 0, 0);
                        }

                        bufferInfo = new MediaCodec.BufferInfo();
                        outputBufferIndex = encoder.dequeueOutputBuffer(bufferInfo, 0);



                        while (outputBufferIndex >= 0)
                        {
                            outputBuffer = outputBuffers[outputBufferIndex];

                            outputBuffer.position(bufferInfo.offset);
                            outputBuffer.limit(bufferInfo.offset + bufferInfo.size);

                            outData = new byte[bufferInfo.size];
                            outputBuffer.get(outData);


                           // Log.d("AudioEncoder", outData.length + " bytes encoded");
                            //-------------
                            packet = new DatagramPacket(outData, outData.length,
                                    InetAddress.getByName("127.0.0.1"), localPort);
                            ds.send(packet);
                            //------------

                            encoder.releaseOutputBuffer(outputBufferIndex, false);
                            outputBufferIndex = encoder.dequeueOutputBuffer(bufferInfo, 0);

                        }
                        // ----------------------;

                    }
                    encoder.stop();
                    recorder.stop();
                }
                catch (Exception e)
                {
                    e.printStackTrace();
                }
            }
        });



        IOudpPlayer = new Thread(new Runnable()
        {
            public void run()
            {
                SocketAddress sockAddress;
                String address;

                int len = 1024;
                byte[] buffer2 = new byte[len];
                DatagramPacket packet;

                byte[] data;

                ByteBuffer[] inputBuffers;
                ByteBuffer[] outputBuffers;

                ByteBuffer inputBuffer;
                ByteBuffer outputBuffer;

                MediaCodec.BufferInfo bufferInfo;
                int inputBufferIndex;
                int outputBufferIndex;
                byte[] outData;
                try
                {
                    player.play();
                    decoder.start();
                    isPlaying = true;
                    while (isPlaying)
                    {
                        try
                        {
                            packet = new DatagramPacket(buffer2, len);
                            ds.receive(packet);

                            sockAddress = packet.getSocketAddress();
                            address = sockAddress.toString();

                         //   Log.d("UDP Receiver"," received !!! from " + address);

                            data = new byte[packet.getLength()];
                            System.arraycopy(packet.getData(), packet.getOffset(), data, 0, packet.getLength());

                           // Log.d("UDP Receiver",  data.length + " bytes received");

                            //===========
                            inputBuffers = decoder.getInputBuffers();
                            outputBuffers = decoder.getOutputBuffers();
                            inputBufferIndex = decoder.dequeueInputBuffer(-1);
                            if (inputBufferIndex >= 0)
                            {
                                inputBuffer = inputBuffers[inputBufferIndex];
                                inputBuffer.clear();

                                inputBuffer.put(data);

                                decoder.queueInputBuffer(inputBufferIndex, 0, data.length, 0, 0);
                            }

                            bufferInfo = new MediaCodec.BufferInfo();
                            outputBufferIndex = decoder.dequeueOutputBuffer(bufferInfo, 0);

                            while (outputBufferIndex >= 0)
                            {
                                outputBuffer = outputBuffers[outputBufferIndex];

                                outputBuffer.position(bufferInfo.offset);
                                outputBuffer.limit(bufferInfo.offset + bufferInfo.size);

                                outData = new byte[bufferInfo.size];
                                outputBuffer.get(outData);

                              //  Log.d("AudioDecoder", outData.length + " bytes decoded");

                                player.write(outData, 0, outData.length);

                                decoder.releaseOutputBuffer(outputBufferIndex, false);
                                outputBufferIndex = decoder.dequeueOutputBuffer(bufferInfo, 0);

                            }

                            //===========

                        }
                        catch (IOException e)
                        {
                        }
                    }

                    decoder.stop();
                    player.stop();

                }
                catch (Exception e)
                {
                }
            }
        });

//===========================================================
        int rate = findAudioRecord();
        if (rate != -1)
        {
            Log.v("=========media ", "ready: " + rate);
            Log.v("=========media channel ", "ready: " + channelConfig);

            boolean encoderReady = setEncoder(rate);
            Log.v("=========encoder ", "ready: " + encoderReady);
            if (encoderReady)
            {
                boolean decoderReady = setDecoder(rate);
                Log.v("=========decoder ", "ready: " + decoderReady);
                if (decoderReady)
                {
                    Log.d("=======bufferSize========", "" + bufferSize);
                    try
                    {
                        setPlayer(rate);

                        ds = new DatagramSocket(localPort);
                        IOudpPlayer.start();

                        IOrecorder.start();

                    }
                    catch (SocketException e)
                    {
                        e.printStackTrace();
                    }


                }

            }
        }
    }


    protected void onDestroy()
    {

        recorder.release();
        player.release();
        encoder.release();
        decoder.release();

    }
/*
    protected void onResume()
    {

        // isRecording = true;
    }

    protected void onPause()
    {

        isRecording = false;
    }
*/

    private int findAudioRecord()
    {
        for (int rate : new int[]{44100})
        {
            try
            {
                Log.v("===========Attempting rate ", rate + "Hz, bits: " + audioFormat + ", channel: " + channelConfig);
                bufferSize = AudioRecord.getMinBufferSize(rate, channelConfig, audioFormat);

                if (bufferSize != AudioRecord.ERROR_BAD_VALUE)
                {
                    // check if we can instantiate and have a success
                    recorder = new AudioRecord(AudioSource.MIC, rate, channelConfig, audioFormat, bufferSize);

                    if (recorder.getState() == AudioRecord.STATE_INITIALIZED)
                    {
                        Log.v("===========final rate ", rate + "Hz, bits: " + audioFormat + ", channel: " + channelConfig);

                        return rate;
                    }
                }
            }
            catch (Exception e)
            {
                Log.v("error", "" + rate);
            }

        }
        return -1;
    }

    private boolean setEncoder(int rate)
    {
        encoder = MediaCodec.createEncoderByType("audio/mp4a-latm");
        MediaFormat format = new MediaFormat();
        format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
        format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 1);
        format.setInteger(MediaFormat.KEY_SAMPLE_RATE, rate);
        format.setInteger(MediaFormat.KEY_BIT_RATE, 64 * 1024);//AAC-HE 64kbps
        format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectHE);
        encoder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
        return true;
    }

    private boolean setDecoder(int rate)
    {
        decoder = MediaCodec.createDecoderByType("audio/mp4a-latm");
        MediaFormat format = new MediaFormat();
        format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
        format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 1);
        format.setInteger(MediaFormat.KEY_SAMPLE_RATE, rate);
        format.setInteger(MediaFormat.KEY_BIT_RATE, 64 * 1024);//AAC-HE 64kbps
        format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectHE);

        decoder.configure(format, null, null, 0);

        return true;
    }

    private boolean setPlayer(int rate)
    {
        int bufferSizePlayer = AudioTrack.getMinBufferSize(rate, AudioFormat.CHANNEL_OUT_MONO, audioFormat);
        Log.d("====buffer Size player ", String.valueOf(bufferSizePlayer));

        player= new AudioTrack(AudioManager.STREAM_MUSIC, rate, AudioFormat.CHANNEL_OUT_MONO, audioFormat, bufferSizePlayer, AudioTrack.MODE_STREAM);


        if (player.getState() == AudioTrack.STATE_INITIALIZED)
        {

            return true;
        }
        else
        {
            return false;
        }

    }


}

Answer 6

I have tested with your souce. there are some points.

1. Bit Rate is a natural number of K, but not computer K. 64k = 64000, but not 64 * 1024

2. It's not recommended to write a long code that shares some variables. A. separate Encoder Thread and Decoder Thread into 2 independet classes. B. The DatagramSocket is shared by Sender and Receiver, it not good.

3. Enumerate Audio Format need more values. i.e. sample rates should be picked from : 8000, 11025, 22050, 44100