Capturing Sound for Analysis and Visualizing Frequencies in Android

Question

I\'m new in Android and I\'m trying to make a program which captures an audio sound and then displays the frequencies that exist within it. I found an example that draws t

Answer 1

Here is the working code. I tried it myself. It works fine.

package com.example.frequencytest;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import ca.uol.aig.fftpack.RealDoubleFFT;

public class MainActivity extends Activity implements OnClickListener {

    int frequency = 8000;
    int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;
    int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;
    private RealDoubleFFT transformer;
    int blockSize = 256;

    Button startStopButton;
    boolean started = false;

    RecordAudio recordTask;

    ImageView imageView;
    Bitmap bitmap;
    Canvas canvas;
    Paint paint;

    //AudioRecord audioRecord;

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

        startStopButton = (Button) this.findViewById(R.id.start_stop_btn);
        startStopButton.setOnClickListener(this);

        transformer = new RealDoubleFFT(blockSize);

        imageView = (ImageView) this.findViewById(R.id.imageView1);
        bitmap = Bitmap.createBitmap((int) 256, (int) 100,
                Bitmap.Config.ARGB_8888);
        canvas = new Canvas(bitmap);
        paint = new Paint();
        paint.setColor(Color.GREEN);
        imageView.setImageBitmap(bitmap);

    }

    public class RecordAudio extends AsyncTask {

        @Override
        protected Void doInBackground(Void... arg0) {

            try {
                // int bufferSize = AudioRecord.getMinBufferSize(frequency,
                // AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
                int bufferSize = AudioRecord.getMinBufferSize(frequency, 
                        channelConfiguration, audioEncoding); 

                AudioRecord audioRecord = new AudioRecord( 
                        MediaRecorder.AudioSource.MIC, frequency, 
                        channelConfiguration, audioEncoding, bufferSize); 

                short[] buffer = new short[blockSize];
                double[] toTransform = new double[blockSize];

                audioRecord.startRecording();

                // started = true; hopes this should true before calling
                // following while loop

                while (started) {
                    int bufferReadResult = audioRecord.read(buffer, 0,
                            blockSize);

                    for (int i = 0; i < blockSize && i < bufferReadResult; i++) {
                        toTransform[i] = (double) buffer[i] / 32768.0; // signed
                                                                        // 16
                    }                                       // bit
                        transformer.ft(toTransform);
                        publishProgress(toTransform);



                }

                audioRecord.stop();

            } catch (Throwable t) {
                t.printStackTrace();
                Log.e("AudioRecord", "Recording Failed");
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(double[]... toTransform) {

            canvas.drawColor(Color.BLACK);

            for (int i = 0; i < toTransform[0].length; i++) {
                int x = i;
                int downy = (int) (100 - (toTransform[0][i] * 10));
                int upy = 100;

                canvas.drawLine(x, downy, x, upy, paint);
            }

            imageView.invalidate();

            // TODO Auto-generated method stub
            // super.onProgressUpdate(values);
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        if (started) {
            started = false;
            startStopButton.setText("Start");
            recordTask.cancel(true);
        } else {
            started = true;
            startStopButton.setText("Stop");
            recordTask = new RecordAudio();
            recordTask.execute();
        }
    }
}