如下是qt 代码,opencv 版本3.4.1
1.核心问题是设置cap.set(CV_CAP_PROP_FOURCC, CV_FOURCC(‘M’, ‘J’, ‘P’, ‘G’));
可是不要设置帧率即cap.set(CV_CAP_PROP_FPS, 30);
不知道为啥设置后反而帧率上不去。
2.若是之上的代码仍是未达到预期,并且是在linux系统下使用能够安装如下依赖项
sudo apt-get install libv4l-dev
同时,从新编译opencv库
cmake -D WITH_LIBV4L=ON ../
ps:"…/"不加是不能生效的!
make -j8
make install
linux
int main() { qint64 m_nTime=0; qint32 m_nFrameRate=0; VideoCapture cap(CV_CAP_DSHOW); cv::Mat matframe; if(cap.isOpened()){ cap.release(); qDebug()<<"cap.isOpened() "; } qDebug()<<cap.open(0); Sleep(1000); if(cap.isOpened()){ cap.set(CV_CAP_PROP_FOURCC, CV_FOURCC('M', 'J', 'P', 'G')); cap.set(CV_CAP_PROP_FRAME_WIDTH, 2592); cap.set(CV_CAP_PROP_FRAME_HEIGHT,1944); // cap.set(CV_CAP_PROP_FPS, 30); while ( cap.read(matframe)) { if (matframe.empty()) { qDebug() << "frame is null " << endl; break; } cv::imshow("Input video", matframe); if((QDateTime::currentDateTime().toTime_t() - m_nTime) < 1) { m_nFrameRate++; } else { qDebug()<<"m_nFrameRate:"<< m_nFrameRate << "opencv fps:"<<cap.get(CV_CAP_PROP_FPS); << QDateTime::currentDateTime().toString(); m_nTime = QDateTime::currentDateTime().toTime_t(); m_nFrameRate = 0; } char c = waitKey(1); if(c==27) //ESC退出 break; } } else qDebug()<< "cap.isOpened() is failed !!!" ; cap.release(); }