我对Android不是很了解,已经搜索了相当长一段时间。我想构建一个类似于分贝计的应用程序,实时显示声音水平。如果房间里有噪音,会有某些指示,如果很安静,也会有某些指示。
我完全不知道如何做到这一点。能否有人解释一下麦克风声音级别应用程序的基础知识?如果可能的话,请提供一些代码。
谢谢!
MediaRecorder.getMaxAmplitude()
方法。if (ActivityCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.RECORD_AUDIO},
RECORD_AUDIO);
}
Get the noise level using the MediaRecorder,
mRecorder = new MediaRecorder();
mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mRecorder.setOutputFile("/dev/null");
try {
mRecorder.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
mRecorder.start();
Start the MediaRecorder,
private Runnable mSleepTask = new Runnable() {
public void run() {
//Log.i("Noise", "runnable mSleepTask");
mSensor.start();
if (!mWakeLock.isHeld()) {
mWakeLock.acquire();
}
//Noise monitoring start
// Runnable(mPollTask) will execute after POLL_INTERVAL
mHandler.postDelayed(mPollTask, POLL_INTERVAL);
}
};
Create Runnable Thread to check the noise level frequently,
private Runnable mPollTask = new Runnable() {
public void run() {
double amp = mSensor.getAmplitude();
//Log.i("Noise", "runnable mPollTask");
// Runnable(mPollTask) will again execute after POLL_INTERVAL
mHandler.postDelayed(mPollTask, POLL_INTERVAL);
}
};
使用以下公式将振幅转换为分贝:
return 20 * Math.log10(mRecorder.getMaxAmplitude() / 2700.0);
Monitoring the Voice and Alert for the Louder Noise.
// Create runnable thread to Monitor Voice
private Runnable mPollTask = new Runnable() {
public void run() {
double amp = mSensor.getAmplitude();
//Log.i("Noise", "runnable mPollTask");
updateDisplay("Monitoring Voice...", amp);
if ((amp > mThreshold)) {
callForHelp(amp);
//Log.i("Noise", "==== onCreate ===");
}
// Runnable(mPollTask) will again execute after POLL_INTERVAL
mHandler.postDelayed(mPollTask, POLL_INTERVAL);
}
};
https://developer.android.com/reference/android/media/audiofx/Visualizer.html