PlaySound.java

package com.example.wazoople.samplecalculator;

import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;

public class PlaySound extends Activity {
    public boolean playFreq(int freqOfTone, double duration) { //hz seconds
        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) {
            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.
        return true;
    }
}