Develop Reference

Adding Fragments and Simple UI Elements significantly slows down Audio Processing Algo

I am new to android and I am trying to build an APP to record audio, do FFT to get freq spectrum.
The buffer size of complete audio is 155 * 2048
i.e. 155* AudioRecord.getMinBufferSize(44100, mono_channel, PCM_16bit)
Each chunk from the recorder is of 2048 shorts , i convert type short into type double and pass it to the FFT library. The library returns me the real and imaginary part which i will use to construct the frequency spectrum. Then i append each chunk to an array.
Now here is the problem:
In app 1 there are no UI elements or Fragments just a simple basic button which is attach to a listener that execute an Async task for reading chunks from Audio.Recorder and does FFT on it chunk by chunk ( each chunk = 2048 short). This process (Recording and FFT) for 155 chunks with sample rate 44100 should take 7 seconds ( 2048 * 155 / 44100 ) but the task took around 9 seconds, which is a lag of 2 seconds (which is acceptable).
In app 2 there are 7 fragments with login and signup screen where each fragment is separate from each other and linked to main activity. The same code here does the task (recording and fft) for 155 * 2048 chunks in 40-45 seconds which means the lag is upto 33-37 seconds. This lag is too much for my purpose. What could be the cause of so much lag in app 2 and how can i reduce it ?
Following is the FFT Library Code and Complex Type Code
FFT.java , Complex.java
My application Code
private boolean is_recording = false;
private AudioRecord recorder = null;
int minimum_buffer_size = AudioRecord.getMinBufferSize(SAMPLE_RATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
int bufferSize = 155 * AudioRecord.getMinBufferSize(SAMPLE_RATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
private static final int SAMPLE_RATE = 44100;
private Thread recordingThread = null;
short[] audioBuffer = new short[bufferSize];
MainTask recordTask;
double finalData[];
Complex[] fftArray;
boolean recieved = false;
int data_trigger_point = 10;
int trigger_count = 0;
double previous_level_1 ;
double previous_level_2 ;
double previous_level_3 ;
int no_of_chunks_to_be_send = 30;
int count = 0;
short[] sendingBuffer = new short[minimum_buffer_size * no_of_chunks_to_be_send];
public static final int RequestPermissionCode = 1;
mButton = (ImageButton) view.findViewById(R.id.submit);
mButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (is_recording) {
mButton.setBackgroundResource(R.drawable.play);
stopRecodringWithoutTone();
}
else {
mButton.setBackgroundResource(R.drawable.wait);
is_recording = true;
recordTask = new MainTask();
recordTask.execute();
}
}
});
public class MainTask extends AsyncTask<Void, int[], Void> {
#Override
protected Void doInBackground(Void... arg0) {
try {
recorder = new AudioRecord(
MediaRecorder.AudioSource.DEFAULT,
SAMPLE_RATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT,
minimum_buffer_size);
recorder.startRecording();
short[] buffer_recording = new short[minimum_buffer_size];
int recieve_counter = 0;
while (is_recording) {
if (count < bufferSize) {
int bufferReadResult = recorder.read(buffer_recording, 0, minimum_buffer_size);
System.arraycopy(buffer_recording, 0, audioBuffer, count, buffer_recording.length);
count += bufferReadResult;
System.out.println(count);
finalData = convert_to_double(buffer_recording);
int [] magnitudes = processFFT(finalData);
}
else {
stopRecording();
}
}
}
catch (Throwable t) {
t.printStackTrace();
Log.e("V1", "Recording Failed");
}
return null;
}
#Override
protected void onProgressUpdate(int[]... magnitudes) {
}
}
private int[] processFFT(double [] data){
Complex[] fftTempArray = new Complex[finalData.length];
for (int i=0; i<finalData.length; i++)
{
fftTempArray[i] = new Complex(finalData[i], 0);
}
fftArray = FFT.fft(fftTempArray);
int [] magnitude = new int[fftArray.length/2];
for (int i=0; i< fftArray.length/2; i++) {
magnitude[i] = (int) fftArray[i].abs();
}
return magnitude;
}
private double[] convert_to_double(short data[]) {
double[] transformed = new double[data.length];
for (int j=0;j<data.length;j++) {
transformed[j] = (double)data[j];
}
return transformed;
}
private void stopRecording() {
if (null != recorder) {
recorder.stop();
postAudio(audioBuffer);
recorder.release();
is_recording = false;
recorder = null;
recordingThread = null;
count = 0;
recieved = false;
}
}

I am not sure why there is a lag, however you can circumvent this problem : Run two async tasks, task 1 records the data and stores it in an array. 2nd async task takes chunks form this array and does FFT.

AsyncTask runs at a lower priority to make sure the UI thread will remain responsive. Thus more UI, more delay in AsyncTask
You're facing the delay because of the scheduling of BACKGROUND thread priority by the Linux cgroup that Android uses that has to live with 10% CPU time altogether.
If you go with THREAD_PRIORITY_BACKGROUND + THREAD_PRIORITY_MORE_FAVORABLE
your thread will be lifted with 10% limitation.
So your code will look like this:
protected final Void doInBackground(Void... arg0) {
Process.setThreadPriority(THREAD_PRIORITY_BACKGROUND + THREAD_PRIORITY_MORE_FAVORABLE);
...//your code here
}
If that doesn't work due to some reasons on next call of doInBackground because Android by default resets the priority. In that case, try using Process.THREAD_PRIORITY_FOREGROUND

Generating frequency with AudioTrack

I found the following code, that generates 'noise'. I want to be able to generate a tone. As far as I understood there's some kind of formula involving SIN to generate the tone.
This line generates the noise: rnd.nextBytes(noiseData);
I tried to assign specific value manually to all array elements, but then there's no sound. I found a code that generates a tone, but it doesn't stream it. When I tried to pass the data to my code, the tone is generated for a few seconds and then the app crashes.
Any suggestions how can I generate a tone from this? Thanks
public class Internal extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void onPlayClicked(View v)
{
start();
}
public void onStopClicked(View v)
{
stop();
}
boolean m_stop = false;
AudioTrack m_audioTrack;
Thread m_noiseThread;
Runnable m_noiseGenerator = new Runnable()
{
public void run()
{
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
/* 8000 bytes per second, 1000 bytes = 125 ms */
byte [] noiseData = new byte[1000];
Random rnd = new Random();
while(!m_stop)
{
rnd.nextBytes(noiseData);
m_audioTrack.write(noiseData, 0, noiseData.length);
}
}
};
void start()
{
m_stop = false;
/* 8000 bytes per second*/
m_audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, AudioFormat.CHANNEL_OUT_MONO,
AudioFormat.ENCODING_PCM_8BIT, 8000 /* 1 second buffer */,
AudioTrack.MODE_STREAM);
m_audioTrack.play();
m_noiseThread = new Thread(m_noiseGenerator);
m_noiseThread.start();
}
void stop()
{
m_stop = true;
m_audioTrack.stop();
}
}
This is the code that generates a tone, but when I feed its output to my write buffer, it plays for a second and then the app crashes.. even though I changed 'AudioFormat.ENCODING_PCM_8BIT' to 'AudioFormat.ENCODING_PCM_16BIT'
private final int duration = 1; // seconds
private final int sampleRate = 8000;
private final int numSamples = duration * sampleRate;
private final double sample[] = new double[numSamples];
private final double freqOfTone = 440; // hz
private final byte generatedSnd[] = new byte[2 * numSamples];
void genTone(){
// fill out the array
for (int i = 0; i < numSamples; ++i) {
sample[i] = Math.sin(2 * Math.PI * i / (sampleRate/freqOfTone));
}
// convert to 16 bit pcm sound array
// assumes the sample buffer is normalised.
int idx = 0;
for (final double dVal : sample) {
// scale to maximum amplitude
final short val = (short) ((dVal * 32767));
// in 16 bit wav PCM, first byte is the low order byte
generatedSnd[idx++] = (byte) (val & 0x00ff);
generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
}
}

Be sure that your noiseData buffer size is greater or equal than the minimum buffersize AudioTrack will return you with getMinBufferSize.
http://developer.android.com/reference/android/media/AudioTrack.html#getMinBufferSize(int, int, int)

A simple Real-Time Mic Meter in Android

I have helped from the book Pro Android media...
Here is the code:
public class MicMeter extends Activity implements OnClickListener {
RecordAudio recordTask;
int blocksize = 256;
int frequency = 8000;
int channelConfig = AudioFormat.CHANNEL_CONFIGURATION_MONO;
int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;
TextView txt;
Button start;
boolean started = false;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mic_meter);
start = (Button)findViewById(R.id.button1);
txt = (TextView)findViewById(R.id.textView1);
start.setOnClickListener(this);
}
private class RecordAudio extends AsyncTask <Void,double[],Void>{
#Override
protected Void doInBackground(Void... params) {
try{
int bufferSize = AudioRecord.getMinBufferSize(frequency,channelConfig,audioEncoding);
AudioRecord audioRecord = new AudioRecord( MediaRecorder.AudioSource.MIC, frequency, channelConfig, audioEncoding, bufferSize);
short[] buffer = new short[blocksize];
double[] meter = new double[blocksize];
audioRecord.startRecording();
while(started){
int bufferReadResult = audioRecord.read(buffer, 0, blocksize);
for (int i = 0; i < blocksize && i < bufferReadResult; i++) {
meter[i] = (double) buffer[i] / 32768.0; // signed 16 bit
}
publishProgress(meter);
}
audioRecord.stop();
}catch (Throwable t) {
Log.e("AudioRecord","RecordingFail");
}
return null;
}
#Override
protected void onProgressUpdate(double[]... meter) {
for(int i = 0 ; i < meter[0].length ; i++){
double[] helper = meter[i];
txt.setText(Double.toString(helper));
}
}
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(started){
recordTask.cancel(true);
}else{
started = true;
recordTask = new RecordAudio();
recordTask.execute();
}
}
}
while i press the button.
It shows 255.0 and then it doesn't response...
Are there any way to fix it??
Are there any beter version about this?
thank

for(int i = 0 ; i < meter[0].length ; i++){
double helper = i;
txt.setText(Double.toString(helper));
setText overwrites the old value. So only the last call will show. The last call sets it to helper, which will always be meter[0].length. Since that's a fixed number, it won't change.

How to get noise level using the built-in microphone in Android

What I want is to be able to get the current noise level in decibels (dB) on the click of a Button. I have been playing around with the sensors and can get them to work easily but this.. I'm stumped. I've tried a few codes but none work, or helped me understand this.
How can this be achieved?
EDIT:
I use the following code:
private Thread recordingThread;
private int bufferSize = 800;
private short[][] buffers = new short[256][bufferSize];
private int[] averages = new int[256];
private int lastBuffer = 0;
AudioRecord recorder;
boolean recorderStarted = false;
protected void startListenToMicrophone()
{
if (!recorderStarted)
{
recordingThread = new Thread()
{
#Override
public void run()
{
int minBufferSize = AudioRecord.getMinBufferSize(8000,
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
recorder = new AudioRecord(AudioSource.MIC, 8000,
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT, minBufferSize * 10);
recorder.setPositionNotificationPeriod(bufferSize);
recorder.setRecordPositionUpdateListener(new OnRecordPositionUpdateListener()
{
#Override
public void onPeriodicNotification(AudioRecord recorder)
{
short[] buffer = buffers[++lastBuffer
% buffers.length];
recorder.read(buffer, 0, bufferSize);
long sum = 0;
for (int i = 0; i < bufferSize; ++i)
{
sum += Math.abs(buffer[i]);
}
averages[lastBuffer % buffers.length] = (int) (sum / bufferSize);
lastBuffer = lastBuffer % buffers.length;
Log.i("dB", ""+averages);
tv4.setText("" + averages[1]);
}
#Override
public void onMarkerReached(AudioRecord recorder)
{
}
});
recorder.startRecording();
short[] buffer = buffers[lastBuffer % buffers.length];
recorder.read(buffer, 0, bufferSize);
while (true)
{
if (isInterrupted())
{
recorder.stop();
recorder.release();
break;
}
}
}
};
recordingThread.start();
recorderStarted = true;
}
}
private void stopListenToMicrophone()
{
if (recorderStarted)
{
if (recordingThread != null && recordingThread.isAlive()
&& !recordingThread.isInterrupted())
{
recordingThread.interrupt();
}
recorderStarted = false;
}
}
}
I have two buttons in my app. First one calls startListenToMicrophone and second calls the stop. I don't understand how this works. I got the code from here.
The textview gets a weird and very big value. What I need is the sound level in decibels.

Just a passing thought and I may be ver very wrong but, amplitude in dB=20xlog(S1/S2).
I couldn't find this calculation anywhere in your code. what you need to do is get S1, which will be the current recorded level and get S2 which needs to be the maximum possible value to record. Then calculate the dB value.

AudioTrack no sound with tone generation

I'm trying to get Android's AudioTrack play a squarewave with the following code
public Synthesizer() {
bufferSize = android.media.AudioTrack.getMinBufferSize(44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT);
player = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize,
AudioTrack.MODE_STREAM);
}
public void writeSamples(byte[] samples) {
fillBuffer(samples);
player.write(buffer, 0, samples.length);
}
private void putBuffer(byte[] samples) {
if (buffer.length < samples.length)
buffer = new byte[samples.length];
for (int i = 0; i < samples.length; i++)
buffer[i] = samples[i];
Even samples will be negative, the others will be positive, to get a square wave:
btnPlay.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
int frequency = 44100;
byte[] sample = new byte[frequency];
for (int i = 0; i < frequency; i++) {
if (i % 2 == 0) {
sample[i] = Byte.MAX_VALUE;
}
else {
sample[i] = Byte.MIN_VALUE;
}
}
squareSynth.writeSamples(sample);
Unfortunately I get no sound at all, i've checked my volume but couldn't even get static or some crackle. I find this very strange. Anyone knows how to fix it?