Непрерывная генерация сигнала

// originally from [url]http://marblemice.blogspot.com/2010/04/generate-and-play-tone-in-android.html[/url]
    // and modified by Steve Pomeroy <steve@staticfree.info>
    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
    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();
 
    }

// Usage:
//    AudioTrack tone = generateTone(440, 250);
//    tone.play();
//
private AudioTrack generateTone(double freqHz, int durationMs)
{
    int count = (int)(44100.0 * 2.0 * (durationMs / 1000.0)) & ~1;
    short[] samples = new short[count];
    for(int i = 0; i < count; i += 2){
        short sample = (short)(Math.sin(2 * Math.PI * i / (44100.0 / freqHz)) * 0x7FFF);
        samples[i + 0] = sample;
        samples[i + 1] = sample;
    }
    AudioTrack track = new AudioTrack(AudioManager.STREAM_MUSIC, 44100,
        AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT,
        count * (Short.SIZE / 8), AudioTrack.MODE_STATIC);
    track.write(samples, 0, count);
    return track;
}

[JAVA]public void sound(double frequency,double durationMs) {
int count = (int)(48000.0 * 2.0 * (durationMs / 1000.0)) & ~1;
short[] samples = new short[count];
for(int i = 0; i < count; i += 2){
short sample = (short)(Math.sin(2 * Math.PI * i / (48000.0 / frequency)) * 0x7FFF);
samples[i] = sample;
samples[i + 1] = sample;
}
if (audioTrack == null) {
audioTrack= new AudioTrack(AudioManager.STREAM_MUSIC, 48000, AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT,count * (Short.SIZE / 8), AudioTrack.MODE_STATIC);
audioTrack.write(samples, 0, count);
audioTrack.setLoopPoints(0, samples.length/2, -1);
audioTrack.play();
audioTrack=null;
}
}