Hello guys, here is the strange stuff i found, calling imshow() and waitKey() functions after a cap >> img; in a loop can speedup the grabbing by halving the time (in my webcam from ~80ms to 40~ms), can someone explain my what's going on? There is a way for having a "fast" grabbing without the imshow()? Here's the code snippet (need C++11 and #include <chrono>):
VideoCapture capture(0);
capture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
capture.set(CV_CAP_PROP_FRAME_HEIGHT, 360);
capture.set(CV_CAP_PROP_FPS, 30);
if(!capture.isOpened()){
cout << "Failed to connect to the camera." << endl;
}
Mat frame;
int i = 60;
while(1){
auto t1 = chrono::high_resolution_clock::now();
capture >> frame;
auto t2 = chrono::high_resolution_clock::now();
cout << "grabbing ms: " << chrono::duration_cast<std::chrono::milliseconds>(t2-t1).count() << endl;
//COMMENT imshow() and see the capture >> frame; taking twice the time
imshow("Debug",tmpFrame);
i--; cout << i << endl;
if(waitKey(32) == 27 || i < 0){
capture.release();
return 0;
}
}