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 but I can not add sound level visualization. How can I do it?

please someone help me a giving suggestion or a sample tutorials link or code.

Answer 1

I like Ali's answer, but here's a simpler version that performs much better. The real speed comes from making the view class's onDraw method as fast as possible. Store the correct values in memory first by doing any computations not required for drawing outside the draw loop, and pass fully populated structures to draw routines to allow the hardware to optimize drawing many lines.

I launched my RecordingActivity and set it full screen, but you can create a layout resource or add the view anywhere.

Actvity:

public class RecordingActivity extends Activity {
    private VisualizerView visualizerView;
    private MediaRecorder recorder = new MediaRecorder();
    private Handler handler = new Handler();
    final Runnable updater = new Runnable() {
        public void run() {
            handler.postDelayed(this, 1);
            int maxAmplitude = recorder.getMaxAmplitude();
            if (maxAmplitude != 0) {
                visualizerView.addAmplitude(maxAmplitude);
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recording);
        visualizerView = (VisualizerView) findViewById(R.id.visualizer);
        try {
            recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
            recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
            recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
            recorder.setOutputFile("/dev/null");
            recorder.prepare();
            recorder.start();
        } catch (IllegalStateException | IOException ignored) {
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        handler.removeCallbacks(updater);
        recorder.stop();
        recorder.reset();
        recorder.release();
    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        handler.post(updater);
    }
}

View:

public class VisualizerView extends View {
    private static final int MAX_AMPLITUDE = 32767;

    private float[] amplitudes;
    private float[] vectors;
    private int insertIdx = 0;
    private Paint pointPaint;
    private Paint linePaint;
    private int width;
    private int height;

    public VisualizerView(Context context, AttributeSet attrs) {
        super(context, attrs);
        linePaint = new Paint();
        linePaint.setColor(Color.GREEN);
        linePaint.setStrokeWidth(1);
        pointPaint = new Paint();
        pointPaint.setColor(Color.BLUE);
        pointPaint.setStrokeWidth(1);
    }

    @Override
    protected void onSizeChanged(int width, int h, int oldw, int oldh) {
        this.width = width;
        height = h;
        amplitudes = new float[this.width * 2]; // xy for each point across the width
        vectors = new float[this.width * 4]; // xxyy for each line across the width
    }

    /**
     * modifies draw arrays. cycles back to zero when amplitude samples reach max screen size
     */
    public void addAmplitude(int amplitude) {
        invalidate();
        float scaledHeight = ((float) amplitude / MAX_AMPLITUDE) * (height - 1);
        int ampIdx = insertIdx * 2;
        amplitudes[ampIdx++] = insertIdx;   // x
        amplitudes[ampIdx] = scaledHeight;  // y
        int vectorIdx = insertIdx * 4;
        vectors[vectorIdx++] = insertIdx;   // x0
        vectors[vectorIdx++] = 0;           // y0
        vectors[vectorIdx++] = insertIdx;   // x1
        vectors[vectorIdx] = scaledHeight;  // y1
        // insert index must be shorter than screen width
        insertIdx = ++insertIdx >= width ? 0 : insertIdx;
    }

    @Override
    public void onDraw(Canvas canvas) {
        canvas.drawLines(vectors, linePaint);
        canvas.drawPoints(amplitudes, pointPaint);
    }
}

Answer 2

Create a xml activity_recording.xml like this.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="180dp"
    android:layout_alignParentBottom="true"
    android:background="#231f20" >

    <ali.visualiser.VisualizerView
        android:id="@+id/visualizer"
        android:layout_width="220dp"
        android:layout_height="75dp"
        android:layout_centerHorizontal="true"
        android:layout_margin="5dp" />

    <TextView
        android:id="@+id/txtRecord"
        android:layout_width="wrap_content"
        android:layout_height="40dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="25dp"
        android:gravity="center"
        android:text="Start Recording"
        android:textColor="@android:color/white"
        android:textSize="30sp" />

</RelativeLayout>

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<Float> 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<Float>(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<files.length; i++) {

                if(files[i].isDirectory()) {                

                }
                else {
                    files[i].delete();
                }
            }
        }
        return true;
    }

    @Override
    protected void onDestroy() {

        super.onDestroy();
        releaseRecorder();
    }

    // updates the visualizer every 50 milliseconds
    Runnable updateVisualizer = new Runnable() {
        @Override
        public void run() {
            if (isRecording) // if we are already recording
            {
                // get the current amplitude
                int x = recorder.getMaxAmplitude();
                visualizerView.addAmplitude(x); // update the VisualizeView
                visualizerView.invalidate(); // refresh the VisualizerView

                // update in 40 milliseconds
                handler.postDelayed(this, REPEAT_INTERVAL);
            }
        }
    };


}

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.