AudioRecord类获取录音音量分贝数

转自:http://www.jb51.net/article/64806.htm
 
public class AudioRecordDemo {
 
  private static final String TAG = "AudioRecord";
  static final int SAMPLE_RATE_IN_HZ = 8000;
  static final int BUFFER_SIZE = AudioRecord.getMinBufferSize(SAMPLE_RATE_IN_HZ,
          AudioFormat.CHANNEL_IN_DEFAULT, AudioFormat.ENCODING_PCM_16BIT);
  AudioRecord mAudioRecord;
  boolean isGetVoiceRun;
  Object mLock;
 
  public AudioRecordDemo() {
    mLock = new Object();
  }
 
  public void getNoiseLevel() {
    if (isGetVoiceRun) {
      Log.e(TAG, "还在录着呢");
      return;
    }
    mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC,
        SAMPLE_RATE_IN_HZ, AudioFormat.CHANNEL_IN_DEFAULT,
        AudioFormat.ENCODING_PCM_16BIT, BUFFER_SIZE);
    if (mAudioRecord == null) {
      Log.e("sound", "mAudioRecord初始化失败");
    }
    isGetVoiceRun = true;
 
    new Thread(new Runnable() {
      @Override
      public void run() {
        mAudioRecord.startRecording();
        short[] buffer = new short[BUFFER_SIZE];
        while (isGetVoiceRun) {
          //r是实际读取的数据长度,一般而言r会小于buffersize
          int r = mAudioRecord.read(buffer, 0, BUFFER_SIZE);
          long v = 0;
          // 将 buffer 内容取出,进行平方和运算
          for (int i = 0; i < buffer.length; i++) {
            v += buffer[i] * buffer[i];
          }
          // 平方和除以数据总长度,得到音量大小。
          double mean = v / (double) r;
          double volume = 10 * Math.log10(mean);
          Log.d(TAG, "分贝值:" + volume);
          // 大概一秒十次
          synchronized (mLock) {
            try {
              mLock.wait(100);
            } catch (InterruptedException e) {
              e.printStackTrace();
            }
          }
        }
        mAudioRecord.stop();
        mAudioRecord.release();
        mAudioRecord = null;
      }
    }).start();
  }
}