How to sample microphone on Android without recording to get live amplitude/level?

Question

I was trying to get the amplitude level of a microphone on Android like so:

MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecord         


        

Answer 1

You can also use mediaRecoder class, to display real time data on UI you need to use Handler:

public class SoundMeter {
private MediaRecorder mediaRecorder;
public  void start(){
    if(started){
        return;
    }
    if (mediaRecorder == null){
        mediaRecorder = new MediaRecorder();

        mediaRecorder.setAudioSource(
                MediaRecorder.AudioSource.MIC);
        mediaRecorder.setOutputFormat(
                MediaRecorder.OutputFormat.THREE_GPP);
        mediaRecorder.setAudioEncoder(
                MediaRecorder.AudioEncoder.AMR_NB);
        mediaRecorder.setOutputFile("/dev/null");

        try{
            mediaRecorder.prepare();
        }catch (IllegalStateException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
        mediaRecorder.start();
        started = true;
    }
}

}
public double getAmplitude(){
    return  mediaRecorder.getMaxAmplitude();
}
}

This part show data on UI:

    private Runnable pollTask = new Runnable() {
    @Override
    public void run() {
        double amplitude = soundMeter.getAmplitude();
        amplitudeTextView.setText("Amplitude: " + amplitude);

        handler.postDelayed(pollTask, 500);
    }
};

Don't forget to call handler in onCreate method:

handler.postDelayed(pollTask, 500);

500 is delay in milliseconds which UI will updated

as you can see here you don't need to save output to file if you set output destination as below it won't save anywhere:

mediaRecorder.setOutputFile("/dev/null");