Android: Audio Recording with voice level visualization

Question

I need to create a android application which is for recording voice while showing the voice(sound) level visualization.

I already created an audio recording application

Answer 1

Create a xml activity_recording.xml like this.

Create a custom visualizerView as given below.

package ali.visualiser;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class VisualizerView extends View {
    private static final int LINE_WIDTH = 1; // width of visualizer lines
    private static final int LINE_SCALE = 75; // scales visualizer lines
    private List amplitudes; // amplitudes for line lengths
    private int width; // width of this View
    private int height; // height of this View
    private Paint linePaint; // specifies line drawing characteristics

    // constructor
    public VisualizerView(Context context, AttributeSet attrs) {
        super(context, attrs); // call superclass constructor
        linePaint = new Paint(); // create Paint for lines
        linePaint.setColor(Color.GREEN); // set color to green
        linePaint.setStrokeWidth(LINE_WIDTH); // set stroke width
    } 

    // called when the dimensions of the View change
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        width = w; // new width of this View
        height = h; // new height of this View
        amplitudes = new ArrayList(width / LINE_WIDTH);
    } 

    // clear all amplitudes to prepare for a new visualization
    public void clear() {
        amplitudes.clear();
    } 

    // add the given amplitude to the amplitudes ArrayList
    public void addAmplitude(float amplitude) {
        amplitudes.add(amplitude); // add newest to the amplitudes ArrayList

        // if the power lines completely fill the VisualizerView
        if (amplitudes.size() * LINE_WIDTH >= width) {
            amplitudes.remove(0); // remove oldest power value
        } 
    } 

    // draw the visualizer with scaled lines representing the amplitudes
    @Override
    public void onDraw(Canvas canvas) {
        int middle = height / 2; // get the middle of the View
        float curX = 0; // start curX at zero

        // for each item in the amplitudes ArrayList
        for (float power : amplitudes) {
            float scaledHeight = power / LINE_SCALE; // scale the power
            curX += LINE_WIDTH; // increase X by LINE_WIDTH

            // draw a line representing this item in the amplitudes ArrayList
            canvas.drawLine(curX, middle + scaledHeight / 2, curX, middle
                    - scaledHeight / 2, linePaint);
        } 
    } 

}

Create RecordingActivity class as given below.

package ali.visualiser;

import java.io.File;
import java.io.IOException;

import android.app.Activity;
import android.media.MediaRecorder;
import android.media.MediaRecorder.OnErrorListener;
import android.media.MediaRecorder.OnInfoListener;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;



public class RecordingActivity extends Activity {
    public static final String DIRECTORY_NAME_TEMP = "AudioTemp";
    public static final int REPEAT_INTERVAL = 40;
    private TextView txtRecord;

    VisualizerView visualizerView;

    private MediaRecorder recorder = null;

    File audioDirTemp;
private boolean isRecording = false;


    private Handler handler; // Handler for updating the visualizer
    // private boolean recording; // are we currently recording?

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

        visualizerView = (VisualizerView) findViewById(R.id.visualizer);

        txtRecord = (TextView) findViewById(R.id.txtRecord);
        txtRecord.setOnClickListener(recordClick);

        audioDirTemp = new File(Environment.getExternalStorageDirectory(),
                DIRECTORY_NAME_TEMP);
        if (audioDirTemp.exists()) {
            deleteFilesInDir(audioDirTemp);
        } else {
            audioDirTemp.mkdirs();
        }

        // create the Handler for visualizer update
        handler = new Handler();
    }   

    OnClickListener recordClick = new OnClickListener() {

        @Override
        public void onClick(View v) {

            if (!isRecording) {
                // isRecording = true;

                txtRecord.setText("Stop Recording");

                recorder = new MediaRecorder();

                recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
                recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
                recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
                recorder.setOutputFile(audioDirTemp + "/audio_file"
                        + ".mp3");

                OnErrorListener errorListener = null;
                recorder.setOnErrorListener(errorListener);
                OnInfoListener infoListener = null;
                recorder.setOnInfoListener(infoListener);

                try {
                    recorder.prepare();
                    recorder.start();
                    isRecording = true; // we are currently recording
                } catch (IllegalStateException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                handler.post(updateVisualizer);

            } else {

                txtRecord.setText("Start Recording");

                releaseRecorder();
            }

        }
    };

    private void releaseRecorder() {
        if (recorder != null) {
            isRecording = false; // stop recording
            handler.removeCallbacks(updateVisualizer);
            visualizerView.clear();
            recorder.stop();
            recorder.reset();
            recorder.release();
            recorder = null;
        }
    }   

    public static boolean deleteFilesInDir(File path) {

        if( path.exists() ) {
            File[] files = path.listFiles();
            if (files == null) {
                return true;
            }
            for(int i=0; i

Result

This is how it looks: https://www.youtube.com/watch?v=BoFG6S02GH0

When it reaches the end, the animation continues as expected: erasing the beginning of the graph.