Develop Reference

Android Wear Audio Recorder using the ChannelAPI

I'm trying to build an audio recorder app for Android Wear. Right now, I'm able to capture the audio on the watch, stream it to phone and save it on a file. However, the audio file is presenting gaps or cropped parts.
I found this aswered questions related to my problem link1, link2, but they couldn't help me.
Here is my code:
First, on the watch side, I create the channel using the channelAPI and sucessfully send the audio being captured on the watch to the smartphone.
//here are the variables values that I used
//44100Hz is currently the only rate that is guaranteed to work on all devices
//but other rates such as 22050, 16000, and 11025 may work on some devices.
private static final int RECORDER_SAMPLE_RATE = 44100;
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
int BufferElements2Rec = 1024;
int BytesPerElement = 2;
//start the process of recording audio
private void startRecording() {
recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
RECORDER_SAMPLE_RATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);
recorder.startRecording();
isRecording = true;
recordingThread = new Thread(new Runnable() {
public void run() {
writeAudioDataToPhone();
}
}, "AudioRecorder Thread");
recordingThread.start();
}
private void writeAudioDataToPhone(){
short sData[] = new short[BufferElements2Rec];
ChannelApi.OpenChannelResult result = Wearable.ChannelApi.openChannel(googleClient, nodeId, "/mypath").await();
channel = result.getChannel();
Channel.GetOutputStreamResult getOutputStreamResult = channel.getOutputStream(googleClient).await();
OutputStream outputStream = getOutputStreamResult.getOutputStream();
while (isRecording) {
// gets the voice output from microphone to byte format
recorder.read(sData, 0, BufferElements2Rec);
try {
byte bData[] = short2byte(sData);
outputStream.write(bData);
} catch (IOException e) {
e.printStackTrace();
}
}
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Then, on the smartphone side, I receive the audio data from the channel and write it to a PCM file.
public void onChannelOpened(Channel channel) {
if (channel.getPath().equals("/mypath")) {
Channel.GetInputStreamResult getInputStreamResult = channel.getInputStream(mGoogleApiClient).await();
inputStream = getInputStreamResult.getInputStream();
writePCMToFile(inputStream);
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(MainActivity.this, "Audio file received!", Toast.LENGTH_SHORT).show();
}
});
}
}
public void writePCMToFile(InputStream inputStream) {
OutputStream outputStream = null;
try {
// write the inputStream to a FileOutputStream
outputStream = new FileOutputStream(new File("/sdcard/wearRecord.pcm"));
int read = 0;
byte[] bytes = new byte[1024];
while ((read = inputStream.read(bytes)) != -1) {
outputStream.write(bytes, 0, read);
}
System.out.println("Done writing PCM to file!");
} catch (Exception e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (outputStream != null) {
try {
// outputStream.flush();
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
What am I doing wrong or what are your suggestions to achieve a perfect gapless audio file on the smartphone? Thanks in advance.

I noticed in your code that you are reading everything into a short[] array, and then converting it to a byte[] array for the Channel API to send. Your code also creates a new byte[] array through each iteration of the loop, which will create a lot of work for the garbage collector. In general, you want to avoid allocations inside loops.
I would allocate one byte[] array at the top, and let the AudioRecord class store it directly into the byte[] array (just make sure you allocate twice as many bytes as you did shorts), with code like this:
mAudioTemp = new byte[bufferSize];
int result;
while ((result = mAudioRecord.read(mAudioTemp, 0, mAudioTemp.length)) > 0) {
try {
mAudioStream.write(mAudioTemp, 0, result);
} catch (IOException e) {
Log.e(Const.TAG, "Write to audio channel failed: " + e);
}
}
I also tested this with a 1 second audio buffer, using code like this, and it worked nicely. I'm not sure what the minimum buffer size is before it starts to have problems:
int bufferSize = Math.max(
AudioTrack.getMinBufferSize(44100, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT),
44100 * 2);

Stream audio record from android device toanother

I want to make stream voice between microphone of android device to speaker of another, so I used Audiorecord !!
The activity that sends voice is :
public class MainActivity extends Activity {
AudioRecord recorder;
private int sampleRate = 44100;
int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
private boolean status = true;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton.setOnClickListener (startListener);
stopButton.setOnClickListener (stopListener);
minBufSize += 4096;
System.out.println("minBufSize: " + minBufSize);
}
private final OnClickListener stopListener = new OnClickListener() {
#Override
public void onClick(View arg0) {
status = false;
recorder.release();
}
};
private final OnClickListener startListener = new OnClickListener() {
#Override
public void onClick(View arg0) {
status = true;
try {
DatagramSocket socket = new DatagramSocket();
Log.d("VS", "Socket Created");
byte[] buffer = new byte[minBufSize];
Log.d("VS","Buffer created of size " + minBufSize);
DatagramPacket packet;
final InetAddress destination = InetAddress.getByName("addresse");
Log.d("VS", "Address retrieved");
recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat,minBufSize*10);
Log.d("VS", "Recorder initialized");
recorder.startRecording();
while(status == true) {
//reading data from MIC into buffer
minBufSize = recorder.read(buffer, 0, buffer.length);
//putting buffer in the packet
packet = new DatagramPacket (buffer,buffer.length,destination,port);
socket.send(packet);
System.out.println("MinBufferSize: " +minBufSize);
}
} catch(UnknownHostException e) {
Log.e("VS", "UnknownHostException");
} catch (IOException e) {
e.printStackTrace();
Log.e("VS", "IOException");
}
}
};
}
and the activity in the android revice is :
public class MainActivity extends Activity {
public static DatagramSocket socket;
private AudioTrack speaker;
private boolean status = true;
#SuppressLint("CutPasteId")
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button1 = (Button) findViewById(R.id.receive_button);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
status = true;
try {
DatagramSocket socket = new DatagramSocket(port);
byte[] buffer = new byte[4096];
//minimum buffer size. need to be careful. might cause problems. try setting manually if any problems faced
int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
speaker = new AudioTrack(AudioManager.STREAM_MUSIC,sampleRate,channelConfig,audioFormat,minBufSize,AudioTrack.MODE_STREAM);
speaker.play();
while(status == true) {
DatagramPacket packet = new DatagramPacket(buffer,buffer.length);
socket.receive(packet);
Log.d("VR", "Packet Received");
buffer=packet.getData();
Log.d("VR", "Packet data read into buffer");
speaker.write(buffer, 0, minBufSize);
Log.d("VR", "Writing buffer content to speaker");
}
} catch(UnknownHostException e) {
Log.e("VS", "UnknownHostException");
} catch (IOException e) {
e.printStackTrace();
Log.e("VS", "IOException");
}
}
});
Button button2 = (Button) findViewById(R.id.receive_button);
button2.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
status = false;
speaker.release();
}
});
}
}
the sender works but when I click the button in the receiver app, that makes error : NULL POINTER EXCEPTION!!
How can I resolve this?
Thanks!

Audio streaming in android

I'm trying to stream audio from an android phone to my pc but I keep getting an Exception.
When pressing the send button it used to be a code that records audio and stream it to the same phone but I altered it to send the recorded data over a socket.
I think it's a memory Exception but what should I do?
byte[] buffer = null;
byte[] byteBuf = null;
byte[][] buffers;
switch (v.getId()) {
case R.id.btnStart: {
Toast.makeText(AudioRecordingActivity.this, "Start Recording",
Toast.LENGTH_SHORT).show();
enableButtons(true);
//here is where I start my code
AudioRecord recorder = null;
boolean stopped =false;
// AudioTrack track = null;
buffers = new byte[65535 ][160000 ];
int ix = 0;
/*
* Initialize buffer to hold continuously recorded audio data, start recording, and start
* playback.
*/
try
{
try {
socket = new Socket("172.16.231.125",4444);
socketOutputStream =socket.getOutputStream();
Toast.makeText(AudioRecordingActivity.this, "Socket was made",
Toast.LENGTH_SHORT).show();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
Toast.makeText(AudioRecordingActivity.this, "Problem",
Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
int N = AudioRecord.getMinBufferSize(8000,AudioFormat.CHANNEL_IN_MONO,AudioFormat.ENCODING_PCM_16BIT);
recorder = new AudioRecord(AudioSource.MIC, 8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, N*10);
// track = new AudioTrack(AudioManager.STREAM_MUSIC, 8000,
// AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, N*10, AudioTrack.MODE_STREAM);
recorder.startRecording();
//track.play();
/*
* Loops until something outside of this thread stops it.
* Reads the data from the recorder and writes it to the audio track for playback.
*/
while(true)
{
buffer = buffers[ix++ % buffers.length];
N = recorder.read(buffer,0,buffer.length);
//ByteBuffer byteBuf = ByteBuffer.allocate(2*N);
// byteBuf = new byte[2*N];
/* int i = 0;
while (N >= i) {
byte b = (byte)(buffer[i]/256);
byteBuf[i]=b;
i++;
}*/
//byte [] bb = byteBuf.array();
try {
socketOutputStream.write( buffer );
socketOutputStream.flush();
Toast.makeText(AudioRecordingActivity.this, "Data was sent",
Toast.LENGTH_SHORT).show();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Toast.makeText(AudioRecordingActivity.this, "can't send",
Toast.LENGTH_SHORT).show();
} catch (IOException e) {
// TODO Auto-generated catch block
Toast.makeText(AudioRecordingActivity.this, "can't send",
Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
//track.write(buffer, 0, buffer.length);
}
}
catch(Throwable x)
{
Toast.makeText(AudioRecordingActivity.this,"Error reading voice audio",
Toast.LENGTH_SHORT).show();
}

Blank gaps appears when recording audio with AudioRecord

I use AudioRecord to record audio from Android, and then reply it using AudioTrack. However, the result is very terrible, it is somehow similar to what it recorded, but it maybe slower (or maybe because it is modified, so I feel like that). When I analyze it carefully, I realize that there are many "gaps" (0 value) in my short array.
This is the graph I received:
And the gaps (it repeat that pattern, every about 630bytes of data, there is about 630bytes of 0s):
Here is my code for recording:
protected void onRecordButtonClick() {
if (this.recording) {
this.recording = false;
this.butRecord.setText("Record");
} else {
this.recordBufferSize = AudioRecord.getMinBufferSize(44100, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
this.recorder = new AudioRecord(
MediaRecorder.AudioSource.DEFAULT,
44100,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT,
this.recordBufferSize);
this.recordThread = new Thread(new Runnable() {
#Override
public void run() {
MainActivity.this.onRecording();
}
});
this.recordThread.setPriority(Thread.MAX_PRIORITY);
this.recording = true;
this.butRecord.setText("Stop recording");
this.recordThread.start();
}
}
protected void onRecording() {
this.recordData.clear();
final short[] temp = new short[this.recordBufferSize];
this.recorder.startRecording();
while (this.recording) {
this.recorder.read(temp, 0, this.recordBufferSize);
for (int i = 0; i < temp.length; i ++) {
this.recordData.add(temp[i]);
}
if (this.recordData.size() >= 220500) { this.recording = false; }
}
this.recorder.stop();
// Complete data
this.currentData = new short[this.recordData.size()];
for (int i = 0; i < this.currentData.length; i++) {
this.currentData[i] = this.recordData.get(i);
}
{ // Write to SD Card the result
final File file = new File(Environment.getExternalStorageDirectory(), "record.pcm");
try {
FileOutputStream fos = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(fos);
for (int i = 0; i < this.currentData.length; i++) {
oos.writeShort(this.currentData[i]);
}
oos.flush();
oos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
this.handler.post(new Runnable() {
#Override
public void run() {
MainActivity.this.waveform.setData(MainActivity.this.currentData);
MainActivity.this.butRecord.setText("Record");
final Bitmap bitmap = MainActivity.this.waveform.getDrawingCache();
try {
FileOutputStream fos = new FileOutputStream(new File(Environment.getExternalStorageDirectory(), "cache.png"));
bitmap.compress(CompressFormat.PNG, 100, fos);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
});
}

Android AudioTrack clicks at start and end of sound

I get clicks at the start and end of playing a sound (a wav from the sdcard). It must be something to do with the track buffering but I dont know the solution. Also, I create a new one of these every time the sound plays, is this ok or is there a better way? There are many sounds playing over and over. Here is the code:
public void PlayAudioTrack(final String filePath, final Float f) throws IOException
{
new Thread(new Runnable() { public void run() {
//play sound here
int minSize = AudioTrack.getMinBufferSize( 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT );
AudioTrack track = new AudioTrack( AudioManager.STREAM_MUSIC, 44100,
AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT,
minSize, AudioTrack.MODE_STREAM);
track.setPlaybackRate((int) (44100*f));
if (filePath==null)
return;
int count = 512 * 1024;
//Read the file..
byte[] byteData = null;
File file = null;
file = new File(filePath);
byteData = new byte[(int)count];
FileInputStream in = null;
try {
in = new FileInputStream( file );
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int bytesread = 0, ret = 0;
int size = (int) file.length();
while (bytesread < size) {
try {
ret = in.read( byteData,0, count);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
track.play();
if (ret != -1) {
// Write the byte array to the track
track.write(byteData,0, ret); bytesread += ret;
}
else break; }
try {
in.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} track.stop(); track.release();
}
}).start();
}
Many thanks for any help

Isn't it possible that you play the PCM wave file header too?
Each PCM wave file has a small header at the beginning of the file, if you play that, you play the header bytes which could result in a click at te beginning.

I have had these same clicks at the beginning of each track using AudioTrack. I solved it by turning track volume off, waiting half a second, and then restoring normal volume. I no longer have any clicks. Here's the relevant bit of the code.
at.play();
at.setStereoVolume (0.0f, 0.0f);
new Thread (new Runnable(){
public void run() {
try{
Thread.sleep(500);
} catch (InterruptedException ie) { ; }
at.setStereoVolume (1.0f, 1.0f);
}
}).start();
new Thread (new Runnable(){
public void run() {
int i = 0;
try{
buffer = new byte[512];
while(((i = is.read(buffer)) != -1) && !paused){
at.write(buffer, 0, i);
position += i;
}
} catch (IOException e) {
e.printStackTrace();
}
if (!paused){
parent.trackEnded();
}
}
}).start();
}