main.cpp

#include <iostream> // for standard I/O
#include <string>   // for strings

#include <opencv2/core/core.hpp>        // Basic OpenCV structures (cv::Mat)
#include <opencv2/highgui/highgui.hpp>  // Video write

using namespace std;
using namespace cv;

int main() {
	VideoCapture cap(0);
	double w = cap.get(CV_CAP_PROP_FRAME_WIDTH);
	double h = cap.get(CV_CAP_PROP_FRAME_HEIGHT);
	cout << "frame size" << w << " " << h << endl;

	namedWindow("Video", CV_WINDOW_AUTOSIZE);

	while (1) {
		Mat frame;
		bool success = cap.read(frame);
		if (!success) {
			cout << "couldn't read video" << endl;
		}
		imshow("Video", frame);
		if (waitKey(30) == 27) {
			cout << "exit" << endl;
			break;
		}
	}
}	

Makefile

CC=g++
CFLAGS=-Wall -Werror
LDFLAGS=-lopencv_core -lopencv_highgui

all: main

OBJS = main.o

main: $(OBJS)
	$(CC) -o $@ $(OBJS) $(LDFLAGS) 

main.o: main.cpp
	$(CC) -o $@ $(CFLAGS) -c $<

clean:
	rm main $(OBJS)