android获取音量分贝值

AudioRecordDemo.java

%title插图%num
package com.example.recording;

import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.util.Log;

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);
if(volume>80){
Log.d(TAG, “恭喜您获得一元优惠券”);
}

// 大概一秒十次
synchronized (mLock) {
try {
mLock.wait(100);

} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
mAudioRecord.stop();
mAudioRecord.release();
mAudioRecord = null;
}
}).start();
}
}
MediaRecorderDemo.java

package com.example.recording;

import java.io.File;
import java.io.IOException;

import android.media.MediaRecorder;
import android.os.Handler;
import android.util.Log;

public class MediaRecorderDemo {
private final String TAG = “MediaRecord”;
private MediaRecorder mMediaRecorder;
public static final int MAX_LENGTH = 1000 * 60 * 10;// *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);
}
}
}
MainActivity.java

package com.example.recording;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
new AudioRecordDemo().getNoiseLevel();

}

}
activity_main.xml

<RelativeLayout xmlns:android=”http://schemas.android.com/apk/res/android”
xmlns:tools=”http://schemas.android.com/tools”
android:layout_width=”match_parent”
android:layout_height=”match_parent”
android:paddingBottom=”@dimen/activity_vertical_margin”
android:paddingLeft=”@dimen/activity_horizontal_margin”
android:paddingRight=”@dimen/activity_horizontal_margin”
android:paddingTop=”@dimen/activity_vertical_margin”
tools:context=”.MainActivity” >

<TextView
android:layout_width=”wrap_content”
android:layout_height=”wrap_content”
android:text=”@string/hello_world” />

</RelativeLayout>
*后别忘 了，在AndroidManifest.xml中配置
<uses-permission android:name=”android.permission.RECORD_AUDIO” />
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