Issue encoding and decoding an audio recording to G711 ( PCMU - uLaw) format

Question

There isn't too much info about apply this codec when we need to streaming audio. Without apply the codec, my code work like a charm establishing a communication between 2 devices but I need encode/decode in that format because I will need streaming with the server and not between two devices (I am testing this code using 2 devices). I am looking for the chance if anyone of your could see where is the key of my problem. I've tried different configurations of the input parameters. Maybe, the codecs that I am using are wrong (I took them from one project with Apache license.) This values are set in the recorder-sender as in the player-receiver device: ``` private int port=50005; private int sampleRate = 8000 ;//44100; private int channelConfig = AudioFormat.CHANNEL_OUT_MONO; private int audioFormat = AudioFormat.ENCODING_PCM_16BIT; int minBufSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat); ``` Note: CHANNEL_OUT_MONO in the player and CHANNEL_IN_MONO in the rec…

Accepted Answer

Ok guys, finally I resolved for myself the problem encoding/decoding audio. It's been a annoying task during the last week. The main problem of my code was the encoding was well done but the decoding wasn't so I was working around it and modify these class with the help of other resources and I've created my own encoding/decoding methods (and these are working like a charm!!!).

Other important decision was to change the encoding format. Now I am using alaw, and not anymore ulaw. The only reason why I did this change is because programmatically is easier to implement alaw than ulaw.

Also I had to play a lot with the parameters as a buffers sizes, etc etc.

I will submit my code and I hope that someone of you could save so much time using my references.

```
    private int port=50005;
private int sampleRate = 8000; //44100;
private int channelConfig = AudioFormat.CHANNEL_IN_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);

public void startStreamingEncoding() {

Thread streamThread = new Thread(new Runnable() {

@Override
        public void run() {
            try {

android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

DatagramSocket socket = new DatagramSocket();

byte[] buffer = new byte[4096];

DatagramPacket packet;

final InetAddress destination = InetAddress.getByName(ip_receiver);

recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat, minBufSize * 10);

recorder.startRecording();

/////Encoding:
                CMG711 encoder = new CMG711();
                byte[] outBuffer = new byte[4096];

int read, encoded;
                File sdCard = Environment.getExternalStorageDirectory();
                FileOutputStream out = new FileOutputStream( new File( sdCard ,"audio-bernard.raw" ));

while(status == true) {

//reading data from MIC into buffer
                    read = recorder.read(buffer, 0, buffer.length);
                    Log.d(getTag(), "read: "+read );

//Encoding:
                    encoded = encoder.encode(buffer,0, read, outBuffer);

//putting buffer in the packet
                    packet = new DatagramPacket (outBuffer, encoded, destination,port);
                    out.write( outBuffer, 0, encoded );

socket.send(packet);
                }

} catch(UnknownHostException e) {
                Log.e("VS", "UnknownHostException");
            } catch (IOException e) {
                e.printStackTrace();
                Log.e("VS", "IOException");
            } 
        }

});
    streamThread.start();
 }
```

And for the receiver and player class or method:

```
private int port=50005;
private int sampleRate = 8000 ;//44100;
private int channelConfig = AudioFormat.CHANNEL_OUT_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);

public void playerAudioDecodingBernard()
    {
        Thread thrd = new Thread(new Runnable() {
            @Override
            public void run() 
            {
                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

AudioTrack track = new AudioTrack(AudioManager.STREAM_MUSIC, 
                        sampleRate, AudioFormat.CHANNEL_OUT_MONO, 
                        AudioFormat.ENCODING_PCM_16BIT, minBufSize * 10, 
                        AudioTrack.MODE_STREAM);

CMG711 decoder = new CMG711();

try
                {
                    DatagramSocket sock = new DatagramSocket(port);
                    byte[] buf = new byte[4096];

int frame = 0;
                    while(true)
                    {
                        DatagramPacket pack = new DatagramPacket(buf, 4096);
                        sock.receive(pack);

//Decoding:                         
                        int size = pack.getLength();
                        //Log.d( "Player", "Player: "+ size +", "+pack.getLength() + ", "+pack.getOffset() );
                        byte[] byteArray = new byte[size*2];

decoder.decode(pack.getData(), 0, size, byteArray);
                        track.write(byteArray, 0, byteArray.length);

if( frame++ > 3 )
                            track.play();
                    }
                }
                catch (SocketException se)
                {
                    Log.e("Error", "SocketException: " + se.toString());
                }
                catch (IOException ie)…

Issue encoding and decoding an audio recording to G711 ( PCMU - uLaw) format

Solution

Problem