和我的团队正在创建一个应用程序,该应用程序包含显示 rmsDb 值的旁路音频源。我们希望得到一个范围从 -155 到 0 的比例,但我们得到的值范围从 -70 到 -19。我们不知道音阶出了什么问题,因为我们都是音频编程的新手。
编辑:这与Google Project Tango有关,因为我们使用的设备是联想Phab2Pro,这是唯一一款支持Tango的商用设备,我们专门为使用Tango进行音频工作而购买。 因此,这影响了探戈技术的采用。
public class RecordingThread {
private static final String LOG_TAG = RecordingThread.class.getSimpleName();
private static final int SAMPLE_RATE = 22050;
public float centerFrequency = 1000;
private short[] audioBuffer;
private short[] audioBuffer2;
private double rms;
private double mGain;
private double rmsdB;
public RecordingThread(AudioDataReceivedListener listener) {
mListener = listener;
}
private boolean mShouldContinue;
private AudioDataReceivedListener mListener;
private Thread mThread;
public boolean recording() {
return mThread != null;
}
public void startRecording() {
if (mThread != null)
return;
mShouldContinue = true;
mThread = new Thread(new Runnable() {
@Override
public void run() {
record();
}
});
mThread.start();
}
public void stopRecording() {
if (mThread == null)
return;
mShouldContinue = false;
mThread = null;
}
private void record() {
rms = 0;
android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_URGENT_AUDIO);
// buffer size in bytes
int bufferSize = AudioRecord.getMinBufferSize(SAMPLE_RATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
if (bufferSize == AudioRecord.ERROR || bufferSize == AudioRecord.ERROR_BAD_VALUE) {
bufferSize = SAMPLE_RATE * 2;
}
audioBuffer = new short[bufferSize / 2];
audioBuffer2 = new short[bufferSize / 2];
AudioRecord record = new AudioRecord(MediaRecorder.AudioSource.DEFAULT,
SAMPLE_RATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT,
bufferSize);
if (record.getState() != AudioRecord.STATE_INITIALIZED) {
Log.e(LOG_TAG, "Audio Record can't initialize!");
return;
}
record.startRecording();
Log.v(LOG_TAG, "Start recording");
long shortsRead = 0;
while (mShouldContinue) {
int numberOfShort = record.read(audioBuffer, 0, audioBuffer.length);
shortsRead += numberOfShort;
/*
* Noise level meter begins here
*/
// Compute the RMS value. (Note that this does not remove DC).
for (int i = 2; i < audioBuffer.length; i++) {
if(i % 3 == 0) {
audioBuffer2[i] = BiQuad.bqfilter(audioBuffer[i], audioBuffer[i - 1], audioBuffer[i - 2], audioBuffer2[i], audioBuffer2[i - 1], audioBuffer2[i - 2], SAMPLE_RATE, centerFrequency, 5);
rms += audioBuffer2[i] * audioBuffer2[i];
}
}
rms = Math.sqrt(rms / audioBuffer2.length);
mGain = 1.0/32767; //0.0044;
rmsdB = 20.0 * Math.log10(mGain * rms);
}
record.stop();
record.release();
Log.v(LOG_TAG, String.format("Recording stopped. Samples read: %d", shortsRead));
}
}
任何帮助将不胜感激。
可能需要进行一些校准,即向 rmsdB 值添加一个常数。
进行多次测量并与标准声强级计进行比较。
通过制作声音强度(以 dB 为单位,在 y 轴上(与 rmsdB 值(在 x 轴上(的图表,您可以将一条线拟合到这些数据中,然后图形的 y 截距将告诉您要添加的常数,例如
rmsdB = calibrationCostant + 20.0 * Math.log10(mGain * rms);