Audio Synthesis 440 Hz : Audio « Media « Android

1. Android
2. Media
3. Audio

Audio Synthesis 440 Hz

   
package app.test;

import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class Test extends Activity implements OnClickListener {

  Button startSound;
  Button endSound;

  AudioSynthesisTask audioSynth;

  boolean keepGoing = false;

  float synth_frequency = 440; // 440 Hz, Middle A

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

    startSound = (Button) this.findViewById(R.id.StartSound);
    startSound.setOnClickListener(this);

    endSound = (Button) this.findViewById(R.id.EndSound);
    endSound.setOnClickListener(this);

    endSound.setEnabled(false);
  }

  @Override
  public void onPause() {
    super.onPause();
    keepGoing = false;

    endSound.setEnabled(false);
    startSound.setEnabled(true);
  }

  public void onClick(View v) {
    if (v == startSound) {
      keepGoing = true;

      audioSynth = new AudioSynthesisTask();
      audioSynth.execute();

      endSound.setEnabled(true);
      startSound.setEnabled(false);
    } else if (v == endSound) {
      keepGoing = false;

      endSound.setEnabled(false);
      startSound.setEnabled(true);
    }
  }

  private class AudioSynthesisTask extends AsyncTask<Void, Void, Void> {
    @Override
    protected Void doInBackground(Void... params) {
      final int SAMPLE_RATE = 11025;

      int minSize = AudioTrack.getMinBufferSize(SAMPLE_RATE,
          AudioFormat.CHANNEL_CONFIGURATION_MONO,
          AudioFormat.ENCODING_PCM_16BIT);

      AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
          SAMPLE_RATE, AudioFormat.CHANNEL_CONFIGURATION_MONO,
          AudioFormat.ENCODING_PCM_16BIT, minSize,
          AudioTrack.MODE_STREAM);

      audioTrack.play();

      short[] buffer = new short[minSize];

      float angular_frequency = (float) (2 * Math.PI) * synth_frequency
          / SAMPLE_RATE;
      float angle = 0;

      while (keepGoing) {
        for (int i = 0; i < buffer.length; i++) {
          buffer[i] = (short) (Short.MAX_VALUE * ((float) Math
              .sin(angle)));
          angle += angular_frequency;
        }
        audioTrack.write(buffer, 0, buffer.length);
      }

      return null;
    }
  }
}
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

<Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/StartSound" android:text="Start Sound"></Button>
<Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/EndSound" android:text="End Sound"></Button>
</LinearLayout>

   
    
    
  

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