Reading video/camera code in opencv

It is found that the method for reading videos or USB camera in opencv is so simple. The following is the code for reading cameras in opencv2.31:

Int main () {// open the video file // CV: videocapture capture ("bike. avi "); // 0 open default camera CV: videocapture capture (0); // check whether the video is enabled if (! Capture. isopened () return 1; // get the frame rate double rate = capture. get (cv_cap_prop_fps); bool stop (false); CV: mat frame; // current video frame CV: namedwindow ("extracted frame "); // interval between two frames int delay = 1000/rate; // loop playback of all frames while (! Stop) {// read the next frame if (! Capture. read (FRAME) break; // display the image CV: imshow ("extracted frame", frame) in the window; // press any key to stop the video. // If (CV:: waitkey (Delay)> = 0) // stop = true; CV: waitkey (20);} // close the video file capture. release (); Return 0 ;}