修改yv12像素值

YV12内存布局

 1 unsigned char *pY = (unsigned char *)pBuf;
 2 unsigned char *pV = pY + nWidth * nHeight;
 3 unsigned char *pU = pV + (nWidth>>1)*(nHeight>>1);
 4
 5 //加上出入口数字指纹,以便确认识别出来的是哪个口
 6 if(nPort==0)
 7 {
 8 pY[0]=0;
 9 pV[0]=0;
10 pU[0]=0;
11 }
12 else
13 {
14 pY[0]=255;
15 pV[0]=255;
16 pU[0]=255;
17 }