Android录音时获取分贝值的方法代码实例

参考文章android中实时获取音量分贝值详解：

public class mediarecorderdemo { 
  private final string tag = "mediarecord"; 
  private mediarecorder mmediarecorder; 
  public static final int max_length = 1000 * 60 * 10;// 最大录音时长1000*60*10; 
  private string filepath; 
 
  public mediarecorderdemo(){ 
    this.filepath = "/dev/null"; 
  } 
 
  public mediarecorderdemo(file file) { 
    this.filepath = file.getabsolutepath(); 
  } 
 
  private long starttime; 
  private long endtime; 
 
  /** 
   * 开始录音 使用amr格式 
   * 
   *      录音文件 
   * @return 
   */ 
  public void startrecord() { 
    // 开始录音 
    /* ①initial：实例化mediarecorder对象 */ 
    if (mmediarecorder == null) 
      mmediarecorder = new mediarecorder(); 
    try { 
      /* ②setaudiosource/setvediosource */ 
      mmediarecorder.setaudiosource(mediarecorder.audiosource.mic);// 设置麦克风 
      /* ②设置音频文件的编码：aac/amr_nb/amr_mb/default 声音的（波形）的采样 */ 
      mmediarecorder.setoutputformat(mediarecorder.outputformat.default); 
            /* 
       * ②设置输出文件的格式：three_gpp/mpeg-4/raw_amr/default three_gpp(3gp格式 
       * ，h263视频/arm音频编码)、mpeg-4、raw_amr(只支持音频且音频编码要求为amr_nb) 
       */ 
      mmediarecorder.setaudioencoder(mediarecorder.audioencoder.amr_nb); 
 
      /* ③准备 */ 
      mmediarecorder.setoutputfile(filepath); 
      mmediarecorder.setmaxduration(max_length); 
      mmediarecorder.prepare(); 
      /* ④开始 */ 
      mmediarecorder.start(); 
      // audiorecord audiorecord. 
      /* 获取开始时间* */ 
      starttime = system.currenttimemillis(); 
      updatemicstatus(); 
      log.i("action_start", "starttime" + starttime); 
    } catch (illegalstateexception e) { 
      log.i(tag, 
          "call startamr(file mrecaudiofile) failed!" 
              + e.getmessage()); 
    } catch (ioexception e) { 
      log.i(tag, 
          "call startamr(file mrecaudiofile) failed!" 
              + e.getmessage()); 
    } 
  } 
 
  /** 
   * 停止录音 
   * 
   */ 
  public long stoprecord() { 
    if (mmediarecorder == null) 
      return 0l; 
    endtime = system.currenttimemillis(); 
    log.i("action_end", "endtime" + endtime); 
    mmediarecorder.stop(); 
    mmediarecorder.reset(); 
    mmediarecorder.release(); 
    mmediarecorder = null; 
    log.i("action_length", "time" + (endtime - starttime)); 
    return endtime - starttime; 
  } 
 
  private final handler mhandler = new handler(); 
  private runnable mupdatemicstatustimer = new runnable() { 
    public void run() { 
      updatemicstatus(); 
    } 
  }; 
 
  /** 
   * 更新话筒状态 
   * 
   */ 
  private int base = 1; 
  private int space = 100;// 间隔取样时间 
 
  private void updatemicstatus() { 
    if (mmediarecorder != null) { 
      double ratio = (double)mmediarecorder.getmaxamplitude() /base; 
      double db = 0;// 分贝 
      if (ratio > 1) 
        db = 20 * math.log10(ratio); 
      log.d(tag,"分贝值："+db); 
      mhandler.postdelayed(mupdatemicstatustimer, space); 
    } 
  } 
}