android声音检测仪---分贝仪

文章出处：大黑个人博客--android声音检测仪---分贝仪

源码下载地址：https://github.com/halibobo/SoundMeter

背景

最近小区旁边工地施工，今一大早就被工地传来的guang！guang！...吵醒了。很响很响的那种，你们肯定会问具体有多响？具体要多响？怎么描述呢？顿时就萌生出开发一款记录声音响度的app，忙活了一下午于是就出了这个声音检测仪

简介

android端的声音检测程序，实时获取当前周围环境的声压级，也就是平常所说的分贝值

源码

声音采集利用系统的MediaRecorder

/**

* 录音

* @return 是否成功开始录音

*/

public boolean startRecorder(){

if (myRecAudioFile == null) {

return false;

}

try {

mMediaRecorder = new MediaRecorder();

mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);

mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);

mMediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

mMediaRecorder.setOutputFile(myRecAudioFile.getAbsolutePath());

mMediaRecorder.prepare();

mMediaRecorder.start();

isRecording = true;

return true;

} catch(IOException exception) {

mMediaRecorder.reset();

mMediaRecorder.release();

mMediaRecorder = null;

isRecording = false ;

exception.printStackTrace();

}catch(IllegalStateException e){

stopRecording();

e.printStackTrace();

isRecording = false ;

}

return false;

}

/**

* 获取声压值

*/

public float getMaxAmplitude() {

if (mMediaRecorder != null) {

try {

return mMediaRecorder.getMaxAmplitude();

} catch (IllegalArgumentException e) {

e.printStackTrace();

return 0;

}

} else {

return 5;

}

}

在MainActivity中开启一个线程定时获取声压值并转为分贝

private void startListenAudio() {

thread = new Thread(new Runnable() {

@Override

public void run() {

while (isThreadRun) {

try {

if(bListener) {

volume = mRecorder.getMaxAmplitude(); //获取声压值

if(volume > 0 && volume < 1000000) {

World.setDbCount(20 * (float)(Math.log10(volume))); //将声压值转为分贝值

}

}

Thread.sleep(100);

} catch (InterruptedException e) {

e.printStackTrace();

bListener = false;

}

}

}

});

thread.start();

}

自定义显示分贝值得大圆盘View 取名SoundDiscView

private float scaleWidth, scaleHeight;

private int newWidth, newHeight;

private Matrix mMatrix = new Matrix();

private Bitmap indicatorBitmap;

private Paint paint = new Paint();

static final long ANIMATION_INTERVAL = 100;

private void init() {

Bitmap myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.noise_index);

int bitmapWidth = myBitmap.getWidth();

int bitmapHeight = myBitmap.getHeight();

newWidth = getWidth();

newHeight = getHeight();

scaleWidth = ((float) newWidth) /(float) bitmapWidth; // 获取缩放比例

scaleHeight = ((float) newHeight) /(float) bitmapHeight; //获取缩放比例

mMatrix.postScale(scaleWidth, scaleHeight); //设置mMatrix的缩放比例

indicatorBitmap = Bitmap.createBitmap(myBitmap, 0, 0, bitmapWidth, bitmapHeight, mMatrix,true); //获取同等和背景宽高的指针图的bitmap

paint = new Paint();

paint.setTextSize(55);

paint.setAntiAlias(true);

paint.setTextAlign(Paint.Align.CENTER); //抗锯齿

paint.setColor(Color.WHITE);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

currentAngle = getAngle(World.dbCount); //获取指针应该显示的角度

mMatrix.setRotate(getAngle(World.dbCount), newWidth / 2, newHeight * 215 / 460); //片相对位置

canvas.drawBitmap(indicatorBitmap, mMatrix, paint);

postInvalidateDelayed(ANIMATION_INTERVAL);

canvas.drawText((int)World.dbCount+" DB", newWidth/2,newHeight*36/46, paint); //图片相对位置

}

运行发现指针滑动的太突兀，做个缓慢过度

public static float dbCount = 40;

private static float lastDbCount = dbCount;

public static void setDbCount(float dbValue) {

dbCount = lastDbCount + (dbValue - lastDbCount) * 0.2f;

lastDbCount = dbCount;

}

结果

这里的分贝值是手机系统录音时获取的，手机厂商都对这个值设置了上限而且手机厂商之间都是有差别的，所以获取声音的分贝值会有点偏差。但是最终运行起来的效果还是很满意的。下面附上源码

源码下载地址