Home » Android » Playing an arbitrary tone with Android

Playing an arbitrary tone with Android

Posted by: admin November 30, 2017 Leave a comment

Questions:

Is there any way to make Android emit a sound of arbitrary frequency (meaning, I don’t want to have pre-recorded sound files)?

I’ve looked around and ToneGenerator was the only thing I was able to find that was even close, but it seems to only be capable of outputting the standard DTMF tones.

Any ideas?

Answers:

I originally found this example code on a blog, but it had some bugs in it that generated some horrendous sounds. I’ve fixed the bugs and posted the resulting code here. Seems to work well for me!

public class PlaySound extends Activity {
    // originally from http://marblemice.blogspot.com/2010/04/generate-and-play-tone-in-android.html
    // and modified by Steve Pomeroy <[email protected]>
    private final int duration = 3; // 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];

    Handler handler = new Handler();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    @Override
    protected void onResume() {
        super.onResume();

        // Use a new tread as this can take a while
        final Thread thread = new Thread(new Runnable() {
            public void run() {
                genTone();
                handler.post(new Runnable() {

                    public void run() {
                        playSound();
                    }
                });
            }
        });
        thread.start();
    }

    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);

        }
    }

    void playSound(){
        final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                sampleRate, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, generatedSnd.length,
                AudioTrack.MODE_STATIC);
        audioTrack.write(generatedSnd, 0, generatedSnd.length);
        audioTrack.play();
    }
}

Questions:
Answers:

Improving on the above code:

Add amplitude ramp up and ramp down to avoid the clicks.

Add code to determine when the tack has finished playing.

        double duration = 1;                // seconds
        double freqOfTone = 1000;           // hz
        int sampleRate = 8000;              // a number

        double dnumSamples = duration * sampleRate;
        dnumSamples = Math.ceil(dnumSamples);
        int numSamples = (int) dnumSamples;
        double sample[] = new double[numSamples];
        byte generatedSnd[] = new byte[2 * numSamples];


        for (int i = 0; i < numSamples; ++i) {      // Fill the sample array
            sample[i] = Math.sin(freqOfTone * 2 * Math.PI * i / (sampleRate));
        }

        // convert to 16 bit pcm sound array
        // assumes the sample buffer is normalized.
        // convert to 16 bit pcm sound array
        // assumes the sample buffer is normalised.
        int idx = 0;
        int i = 0 ;

        int ramp = numSamples / 20 ;                                    // Amplitude ramp as a percent of sample count


        for (i = 0; i< ramp; ++i) {                                     // Ramp amplitude up (to avoid clicks)
            double dVal = sample[i];
                                                                        // Ramp up to maximum
            final short val = (short) ((dVal * 32767 * i/ramp));
                                                                        // in 16 bit wav PCM, first byte is the low order byte
            generatedSnd[idx++] = (byte) (val & 0x00ff);
            generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
        }


        for (i = i; i< numSamples - ramp; ++i) {                        // Max amplitude for most of the samples
            double dVal = sample[i];
                                                                        // 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);
        }

        for (i = i; i< numSamples; ++i) {                               // Ramp amplitude down
            double dVal = sample[i];
                                                                        // Ramp down to zero
            final short val = (short) ((dVal * 32767 * (numSamples-i)/ramp ));
                                                                        // in 16 bit wav PCM, first byte is the low order byte
            generatedSnd[idx++] = (byte) (val & 0x00ff);
            generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
        }

        AudioTrack audioTrack = null;                                   // Get audio track
        try {
            audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                    sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO,
                    AudioFormat.ENCODING_PCM_16BIT, (int)numSamples*2,
                    AudioTrack.MODE_STATIC);
            audioTrack.write(generatedSnd, 0, generatedSnd.length);     // Load the track
            audioTrack.play();                                          // Play the track
        }
        catch (Exception e){
            RunTimeError("Error: " + e);
            return false;
        }

        int x =0;
        do{                                                     // Montior playback to find when done
             if (audioTrack != null) 
                 x = audioTrack.getPlaybackHeadPosition(); 
             else 
                 x = numSamples;            
        }while (x<numSamples);

        if (audioTrack != null) audioTrack.release();           // Track play done. Release track.

Questions:
Answers:

Here’s another blog demoing a simple synth plus some UI

http://audioprograming.wordpress.com/2012/10/18/a-simple-synth-in-android-step-by-step-guide-using-the-java-sdk/

You might also be interested in csound or pdlib (pure data lib) for android.

Questions:
Answers:

Since there is a bug in some older android versions that causes a memory leak when using MODE_STATIC, I modified Xarph’s answer above to use MODE_STREAM. Hopefully it will help some.

public void playTone(double freqOfTone, double duration) {
 //double duration = 1000;                // seconds
 //   double freqOfTone = 1000;           // hz
    int sampleRate = 8000;              // a number

    double dnumSamples = duration * sampleRate;
    dnumSamples = Math.ceil(dnumSamples);
    int numSamples = (int) dnumSamples;
    double sample[] = new double[numSamples];
    byte generatedSnd[] = new byte[2 * numSamples];


    for (int i = 0; i < numSamples; ++i) {      // Fill the sample array
        sample[i] = Math.sin(freqOfTone * 2 * Math.PI * i / (sampleRate));
    }

    // convert to 16 bit pcm sound array
    // assumes the sample buffer is normalized.
    // convert to 16 bit pcm sound array
    // assumes the sample buffer is normalised.
    int idx = 0;
    int i = 0 ;

    int ramp = numSamples / 20 ;                                    // Amplitude ramp as a percent of sample count


    for (i = 0; i< ramp; ++i) {                                     // Ramp amplitude up (to avoid clicks)
        double dVal = sample[i];
                                                                    // Ramp up to maximum
        final short val = (short) ((dVal * 32767 * i/ramp));
                                                                    // in 16 bit wav PCM, first byte is the low order byte
        generatedSnd[idx++] = (byte) (val & 0x00ff);
        generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
    }


    for (i = i; i< numSamples - ramp; ++i) {                        // Max amplitude for most of the samples
        double dVal = sample[i];
                                                                    // 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);
    }

    for (i = i; i< numSamples; ++i) {                               // Ramp amplitude down
        double dVal = sample[i];
                                                                    // Ramp down to zero
        final short val = (short) ((dVal * 32767 * (numSamples-i)/ramp ));
                                                                    // in 16 bit wav PCM, first byte is the low order byte
        generatedSnd[idx++] = (byte) (val & 0x00ff);
        generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
    }

    AudioTrack audioTrack = null;                                   // Get audio track
    try {
         int bufferSize = AudioTrack.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);
        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                sampleRate, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, bufferSize,
                AudioTrack.MODE_STREAM);
        audioTrack.play();                                          // Play the track
        audioTrack.write(generatedSnd, 0, generatedSnd.length);     // Load the track
    }
    catch (Exception e){
    }
    if (audioTrack != null) audioTrack.release();           // Track play done. Release track.
}

Questions:
Answers:

Modified Code Based on Singhaks’ answer

public class MainActivity extends Activity {
    private final int duration = 30; // 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];
    Handler handler = new Handler();
    private AudioTrack audioTrack;
    private boolean play = false;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                8000, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, numSamples,
                AudioTrack.MODE_STREAM);
    }

    @Override
    protected void onResume() {
        super.onResume();

        // Use a new tread as this can take a while
        Thread thread = new Thread(new Runnable() {
            public void run() {

                handler.post(new Runnable() {

                    public void run() {
                        playSound();
                        genTone();
                    }
                });
            }   
        });
        thread.start();
    }

    void genTone(){
        // fill out the array
        while(play){
                for (int i = 0; i < numSamples; ++i) {
                //  float angular_frequency = 
                    sample[i] = Math.sin(2 * Math.PI * i / (sampleRate/freqOfTone));
                }
                int idx = 0;

                // convert to 16 bit pcm sound array
                // assumes the sample buffer is normalised.
                for (double dVal : sample) {
                    short val = (short) (dVal * 32767);
                    generatedSnd[idx++] = (byte) (val & 0x00ff);
                    generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);
                }
                audioTrack.write(generatedSnd, 0, numSamples);
            }
        }


    void playSound(){
        play = true;
        audioTrack.play();
    }
}

Questions:
Answers:

I wrapped the above wonderful solutions into a neat little package that’s more useable out of the box as a simple configurable buzzer. It runs it in a background thread and has stop and play methods and a handful of options you can set.

It’s up on JCenter so you can add it to your dependencies list like this

compile 'net.mabboud:android-tone-player:0.2'

and you use it like this for a continuous buzzer

ContinuousBuzzer tonePlayer = new ContinuousBuzzer();
tonePlayer.play();

// just an example don't actually use Thread.sleep in your app
Thread.sleep(1000); 
tonePlayer.stop();

or a buzzer played only once and you can set frequency and volume like this

OneTimeBuzzer buzzer = new OneTimeBuzzer();
buzzer.setDuration(5);

// volume values are from 0-100
buzzer.setVolume(50);
buzzer.setToneFreqInHz(110);

Extended blog post here about it here

Questions:
Answers:
    float synth_frequency = 440;
    int minSize = AudioTrack.getMinBufferSize(SAMPLE_RATE,
AudioFormat.CHANNEL_OUT_MONO,
AudioFormat.ENCODING_PCM_16BIT);
AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
SAMPLE_RATE,
AudioFormat.CHANNEL_OUT_MONO,
AudioFormat.ENCODING_PCM_16BIT,
minSize,
AudioTrack.MODE_STREAM);
audioTrack.play();
short[] buffer = new short[minSize];
float angle = 0;
while (true) 
{
    if (play)
    {
        for (int i = 0; i < buffer.length; i++)
        {
            float angular_frequency =
            (float)(2*Math.PI) * synth_frequency / SAMPLE_RATE;
            buffer[i] = (short)(Short.MAX_VALUE * ((float) Math.sin(angle)));
            angle += angular_frequency;
    }
        audioTrack.write(buffer, 0, buffer.length);
    } 

// You can add arbitrary value in synth_frequency to get change sound for example you can add random variable to get sound

Questions:
Answers:

Do major (16 notes)

 public class MainActivity extends AppCompatActivity {

  private double mInterval = 0.125;
  private int mSampleRate = 8000;
  private byte[] generatedSnd;

  private final double mStandardFreq = 440;

  Handler handler = new Handler();
  private AudioTrack audioTrack;


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

  @Override
  protected void onResume() {
    super.onResume();

    // Use a new tread as this can take a while
    final Thread thread = new Thread(new Runnable() {
        public void run() {

            byte[] tempByte = new byte[0];
            for (int i = 0; i < 16 ; i++ ){
                double note = getNoteFrequencies(i);
                byte[] tonByteNote = getTone(mInterval, mSampleRate, note);
                tempByte = concat(tonByteNote, tempByte);
            }
            generatedSnd = tempByte;

            handler.post(new Runnable() {
                public void run() {
                    playTrack(generatedSnd);
                }
            });
        }
    });
    thread.start();
  }

  public byte[] concat(byte[] a, byte[] b) {
    int aLen = a.length;
    int bLen = b.length;
    byte[] c= new byte[aLen+bLen];
    System.arraycopy(a, 0, c, 0, aLen);
    System.arraycopy(b, 0, c, aLen, bLen);
    return c;
  }

  private double getNoteFrequencies(int index){
    return mStandardFreq * Math.pow(2, (double) index/12.0d);
  }

  private byte[] getTone(double duration, int rate, double frequencies){

    int maxLength = (int)(duration * rate);
    byte generatedTone[] = new byte[2 * maxLength];

    double[] sample = new double[maxLength];
    int idx = 0;

    for (int x = 0; x < maxLength; x++){
        sample[x] = sine(x, frequencies / rate);
    }


    for (final double dVal : sample) {

        final short val = (short) ((dVal * 32767));

        // in 16 bit wav PCM, first byte is the low order byte
        generatedTone[idx++] = (byte) (val & 0x00ff);
        generatedTone[idx++] = (byte) ((val & 0xff00) >>> 8);

    }

    return generatedTone;
}

  private AudioTrack getAudioTrack(int length){

    if (audioTrack == null)
        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                mSampleRate, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, length,
                AudioTrack.MODE_STATIC);

    return audioTrack;
  }

  private double sine(int x, double frequencies){
    return Math.sin(  2*Math.PI * x * frequencies);
  }

  void playTrack(byte[] generatedSnd){
    getAudioTrack(generatedSnd.length)
            .write(generatedSnd, 0, generatedSnd.length);
    audioTrack.play();
  }

}

Questions:
Answers:

see this helpful library

https://github.com/karlotoy/perfectTune

it’s easy to use

add this to your dependencies

 compile 'com.github.karlotoy:perfectTune:1.0.2'

And you use it like this:

PerfectTune perfectTune = new PerfectTune();
perfectTune.setTuneFreq(desire_freq);
perfectTune.playTune();

to stop the tune:

perfectTune.stopTune();

Questions:
Answers:

There are several programs for this, but they suck. I measured a few:

http://www.endolith.com/wordpress/2009/11/24/android-audio-applications/

So don’t do whatever they do. 😀