MediaRecorder mMediaRecorder; int ratio = mMediaRecorder.getMaxAmplitude() / BASE; int db = 0;// 分贝 也可以理解为定义的音量大小 if (ratio > 1) db = (int) (20 * Math.log10(ratio));//db就是我们需要取得的音量的值。 //(int) (20 * Math.log10(ratio))振幅和音量大小的公式 //BASE的值由自己测试获得,我是怎么获取这个值得呢? //开启麦克风,不对麦克风说话,而由周围噪声获取的值 大概在300到600之间 我取得是600这个基准值。
一下是一部分应用的代码:
package com.taobao.baby.manager; import java.io.File; import java.io.IOException; import com.taobao.baby.R; import com.taobao.baby.util.Log; import android.media.MediaRecorder; import android.os.Handler; import android.widget.ImageView; /** * amr音频处理 * * @author hongfa.yy * @version 创建时间2012-11-21 下午4:33:28 */ public class RecordManager { private final String TAG = "RecordManager"; private MediaRecorder mMediaRecorder; public static final int MAX_LENGTH = 1000 * 60 * 10;// 最大录音时长1000*60*10; private File file; public RecordManager(File file,ImageView view) { this.file = file; this.view=view; } public RecordManager(File file) { this.file = file; } private long startTime; private long endTime; /** * 开始录音 使用amr格式 * * @param mRecAudioFile * 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.setOutputFormat(MediaRecorder.OutputFormat.AMR_NB); /* 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.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT); /* ③准备 */ mMediaRecorder.setOutputFile(file.getAbsolutePath()); mMediaRecorder.setMaxDuration(MAX_LENGTH); mMediaRecorder.prepare(); /* ④开始 */ mMediaRecorder.start(); // AudioRecord audioRecord. /* 获取开始时间* */ startTime = System.currentTimeMillis(); // pre=mMediaRecorder.getMaxAmplitude(); 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 * * @param mMediaRecorder */ 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 分贝是也就是相对响度 分贝的计算公式K=20lg(Vo/Vi) Vo当前振幅值 Vi基准值为600:我是怎么制定基准值的呢? 当20 * * Math.log10(mMediaRecorder.getMaxAmplitude() / Vi)==0的时候vi就是我所需要的基准值 * 当我不对着麦克风说任何话的时候,测试获得的mMediaRecorder.getMaxAmplitude()值即为基准值。 * Log.i("mic_", "麦克风的基准值:" + mMediaRecorder.getMaxAmplitude());前提时不对麦克风说任何话 */ private int BASE = 600; private int SPACE = 300;// 间隔取样时间 private ImageView view; private void updateMicStatus() { if (mMediaRecorder != null && view != null) { // int vuSize = 10 * mMediaRecorder.getMaxAmplitude() / 32768; int ratio = mMediaRecorder.getMaxAmplitude() / BASE; int db = 0;// 分贝 if (ratio > 1) db = (int) (20 * Math.log10(ratio)); switch (db / 4) { case 0: view.setImageBitmap(null); break; case 1: view.setImageResource(R.drawable.audio_recorder_volume_1); break; case 2: view.setImageResource(R.drawable.audio_recorder_volume_2); break; case 3: view.setImageResource(R.drawable.audio_recorder_volume_3); break; case 4: view.setImageResource(R.drawable.audio_recorder_volume_4); break; case 5: view.setImageResource(R.drawable.audio_recorder_volume_5); break; default: view.setImageResource(R.drawable.audio_recorder_volume_5); break; } mHandler.postDelayed(mUpdateMicStatusTimer, SPACE); /* * if (db > 1) { vuSize = (int) (20 * Math.log10(db)); Log.i("mic_", * "麦克风的音量的大小:" + vuSize); } else Log.i("mic_", "麦克风的音量的大小:" + 0); */ } } }