Original error will be reported

Mat src;
	// use default camera as video source
	VideoCapture cap(0);
	// check if we succeeded
	if (!cap.isOpened()) {
		cerr << "ERROR! Unable to open camera\n";
		return;
	}
	// get one frame from camera to know frame size and type
	cap >> src;
	// check if we succeeded
	if (src.empty()) {
		cerr << "ERROR! blank frame grabbed\n";
		return;
	}
	bool isColor = (src.type() == CV_8UC3);
	//--- INITIALIZE VIDEOWRITER
	VideoWriter writer;
	int codec = VideoWriter::fourcc('H', '2', '6', '4'/*'P','I','M','1'*//*'M', 'J', 'P', 'G'*/);  // select desired codec (must be available at runtime)
	double fps = 30.0;                          // framerate of the created video stream
	string filename = "./h264.avi";             // name of the output video file
	writer.open(filename, codec, fps, src.size(), isColor);
	// check if we succeeded
	if (!writer.isOpened()) {
		cerr << "Could not open the output video file for write\n";
		return;
	}
	//--- GRAB AND WRITE LOOP
	cout << "Writing videofile: " << filename << endl
	<< "Press any key to terminate" << endl;
	int frame_cnt = 0;
	for (;;)
	{
		// check if we succeeded
		if (!cap.read(src) || frame_cnt > 60) {
			cerr << "ERROR! blank frame grabbed\n";
			break;
		}
		// encode the frame into the videofile stream
		writer.write(src);
		frame_cnt += 1;
		// show live and wait for a key with timeout long enough to show images
		imshow("Live", src);
		if (waitKey(5) >= 0)
			break;
	}

• Wrong content
  

Solution

According to the error content of the prompt https://github.com/cisco/openh264/releases Go to the website to download the corresponding openh264-1.8.0-win64.dll The file is placed under the current project folder , Execute again to solve