I was trying to get the amplitude level of a microphone on Android like so:
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
Timer timer = new Timer();
timer.scheduleAtFixedRate(new RecorderTask(recorder), 0, 1000);
private class RecorderTask extends TimerTask {
private MediaRecorder recorder;
public RecorderTask(MediaRecorder recorder) {
this.recorder = recorder;
}
public void run() {
Log.v("MicInfoService", "amplitude: " + recorder.getMaxAmplitude());
}
}
Unfortunately, this only returns 0 all the time.
It appears that for this to work I have to actually start recording. Is that correct?
If so, do I need to record for 500ms, get amplitude, stop recording and repeat?
Finally, do I have to record to a file? I do not need to save this audio file, can't I just get the current amplitude or highest amplitude since last call of the current live microphone input without recording?
Any help is appreciated, thanks.
The solution from Toumal works, however I wasn't able to get a high enough refresh rate for my needs. So I ended up using the SoundMeter.java class that Toumal linked but modified it to use the code from this answer
Here is the code I used, which provides a much better refresh rate:
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
public class SoundMeter {
private AudioRecord ar = null;
private int minSize;
public void start() {
minSize= AudioRecord.getMinBufferSize(8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
ar = new AudioRecord(MediaRecorder.AudioSource.MIC, 8000,AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT,minSize);
ar.startRecording();
}
public void stop() {
if (ar != null) {
ar.stop();
}
}
public double getAmplitude() {
short[] buffer = new short[minSize];
ar.read(buffer, 0, minSize);
int max = 0;
for (short s : buffer)
{
if (Math.abs(s) > max)
{
max = Math.abs(s);
}
}
return max;
}
}