问题
I'm trying to get the Sound Level Pressure
expressed in decibel
but I always get 0
. (The output of the TextView
is -Infinity but because log(0) = -infinity.
public class SLP extends Activity{
TextView sound;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sound_activity);
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
Timer timer = new Timer();
timer.scheduleAtFixedRate(new RecorderTask(recorder), 0, 500);
}
private class RecorderTask extends TimerTask {
TextView sound = (TextView) findViewById(R.id.decibel);
private MediaRecorder recorder;
public RecorderTask(MediaRecorder recorder) {
this.recorder = recorder;
}
public void run() {
runOnUiThread(new Runnable() {
@Override
public void run() {
int amplitude = recorder.getMaxAmplitude();
double amplitudeDb = 20 * Math.log10((double)Math.abs(amplitude) / 32768);
sound.setText("" + amplitudeDb);
}
});
}
}
The permission in the Manifest.xml
:
<uses-permission android:name="android.permission.RECORD_AUDIO" />
Could you help me please?
Update
I tried with this too:
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile("/dev/null");
try {
recorder.prepare();
} catch (IOException e) {
e.printStackTrace();
}
recorder.start();
Timer timer = new Timer();
timer.scheduleAtFixedRate(new RecorderTask(recorder), 0, 500);
recorder.reset();
}
private class RecorderTask extends TimerTask {
TextView risultato = (TextView) findViewById(R.id.decibel);
private MediaRecorder recorder;
public RecorderTask(MediaRecorder recorder) {
this.recorder = recorder;
}
public double getAmplitude() {
if (recorder != null)
return (recorder.getMaxAmplitude());
else
return 0;
}
public void run() {
runOnUiThread(new Runnable() {
@Override
public void run() {
int amplitude = recorder.getMaxAmplitude();
double amplitudeDb = 20 * Math.log10(getAmplitude() / 32768);
//double db = 20 * Math.log(recorder.getMaxAmplitude() / 2700.0);
risultato.setText("" + amplitudeDb);
}
});
}
}
but nothing, still getting -Infinite
回答1:
Try with this:
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
Timer timer = new Timer();
timer.scheduleAtFixedRate(new RecorderTask(recorder), 0, 500);
recorder.setOutputFile("/dev/null");
try {
recorder.prepare();
recorder.start();
} catch(IllegalStateException e)
{
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private class RecorderTask extends TimerTask {
TextView sound = (TextView) findViewById(R.id.decibel);
private MediaRecorder recorder;
public RecorderTask(MediaRecorder recorder) {
this.recorder = recorder;
}
public void run() {
runOnUiThread(new Runnable() {
@Override
public void run() {
int amplitude = recorder.getMaxAmplitude();
double amplitudeDb = 20 * Math.log10((double)Math.abs(amplitude));
sound.setText("" + amplitudeDb);
}
});
}
}
Without / 32768 I get values between 30 db (my room with silence) and 88 db (when I put loud music).
I think they're OK
回答2:
I think you need to call recorder.prepare() and recorder.start() as per the developer notes
UPDATE you also must setOutputFile(file_path);
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(PATH_NAME);
recorder.prepare();
recorder.start(); // Recording is now started
...
recorder.stop();
recorder.reset(); // You can reuse the object by going
回答3:
Below code worked for me, need to set "setAudioSamplingRate" and "setAudioEncodingBitRate"
MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
if (Build.VERSION.SDK_INT >= 10) {
recorder.setAudioSamplingRate(44100);
recorder.setAudioEncodingBitRate(96000);
recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
} else {
// older version of Android, use crappy sounding voice codec
recorder.setAudioSamplingRate(8000);
recorder.setAudioEncodingBitRate(12200);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
}
recorder.setOutputFile(file.getAbsolutePath());
try {
recorder.prepare();
} catch (IOException e) {
throw new RuntimeException(e);
}
来源:https://stackoverflow.com/questions/31305163/getmaxamplitude-always-returns-0