Get amplitude from user's voice

Question

How to detect amplitude from user's voice? Just detect if user speak or not. What is the different between AudioRecorder, MediaRecorder, Audio Capture? Please give me a full explanation and code please

i tried this class from tutorial but it has error in "mRecorder.prepare():"

import android.media.MediaRecorder;

 public class SoundMeter {
    static final private double EMA_FILTER = 0.6;

    private MediaRecorder mRecorder = null;
    private double mEMA = 0.0;

    public void start() {
            if (mRecorder == null) {
                    mRecorder = new MediaRecorder();
                    mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
                    mRecorder.prepare();
                mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
                mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
                mRecorder.setOutputFile("/dev/null"); 

                mRecorder.start();
                mEMA = 0.0;
            }
    }

    public void stop() {
            if (mRecorder != null) {
                    mRecorder.stop();       
                    mRecorder.release();
                    mRecorder = null;
            }
    }

    public double getAmplitude() {
            if (mRecorder != null)
                    return  (mRecorder.getMaxAmplitude()/2700.0);
            else
                    return 0;

    }

    public double getAmplitudeEMA() {
            double amp = getAmplitude();
            mEMA = EMA_FILTER * amp + (1.0 - EMA_FILTER) * mEMA;
            return mEMA;
    }

}

update my second try

     public class MainActivity extends Activity {


 static final private double EMA_FILTER = 0.6;
private MediaRecorder mRecorder = null;
private double mEMA = 0.0;
TextView tv;

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


      mRecorder = new MediaRecorder();
      mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);

      mRecorder.start();
      mEMA = 0.0;


     tv = (TextView) findViewById(R.id.textView1);
    double a = getAmplitude();
    tv.setText(String.valueOf(a));
    new Timer().schedule(new TimerTask() {

        @Override
        public void run() {
            // TODO Auto-generated method stub
            down();
        }
    }, 500, 10);

}
public void down() {
    this.runOnUiThread(Update);
}
private Runnable Update=new Runnable() {

    @Override
    public void run() {
        // TODO Auto-generated method stub
        double a = getAmplitude();
        tv.setText(String.valueOf(a));
    }
};


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}
public double getAmplitude() {
       if (mRecorder != null)
               return  (mRecorder.getMaxAmplitude());
       else
               return 0;

} }

thats my code, but it doesnt work – Alvin Christian Feb 21 '13 at 05:52 — Alvin Christian, Feb 21 '13 at 05:52

mcalex · Answer 1 · 2013-02-21T07:26:11.760

1

A couple of things:

You need to set Output Format before the prepare() statement. From the documentation for prepare(): Throws IllegalStateException if it is called after start() or before setOutputFormat()
MediaRecorder.prepare() also throws IOException. You may want to surround the prepare() with a try/catch construct.

try:

if (mRecorder == null) {
    try {
        mRecorder = new MediaRecorder();
        mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        mRecorder.setOutputFile("/dev/null"); 

        mRecorder.prepare();
        mRecorder.start();
        mEMA = 0.0;
    }
    catch (IOException e) {
        //do something with e
    }
}

edited Feb 21 '13 at 07:26

answered Feb 21 '13 at 06:53

mcalex

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i have an error while debug this, "Source not found", why? – Alvin Christian Feb 21 '13 at 09:21
not sure. which line? (silly question) do you have a mic attached? – mcalex Feb 21 '13 at 09:24
mic? i debug it on my Android device. i just need to detect user's speak or not, still i have to set audio sorce, format, encoder? – Alvin Christian Feb 21 '13 at 09:28
oops lol, of course mic attached. You've already set source (mic) format (3GPP) and encoder (amr narrow band). Also, if you set output file to /dev/null you won't get a recording – mcalex Feb 21 '13 at 09:40
i see in other thread that if i just need to detect sound i dont need to set format and encoder and encoder. Btw if i not use try catch and just declare the Mediaplayer i get error source not found, if i use it and try to get amplitude, th result is always 0.0 Help me Take a look, i updated my answer – Alvin Christian Feb 21 '13 at 09:48

Get amplitude from user's voice

1 Answers1