OpenCV External USB Camera

Recently, we need to use OPENCV Computer Vision Library to read and display and save the video. As a result of the previous use of notebooks, the desktop external USB camera, there are a lot of problems, always show memory problems, Google, Baidu large half-day, summed up the way the great God proposal, finally solved the problem, the problem and code to share to everyone, avoid detours. The cause of the problem occurs: 1. The camera initialization takes time, enters the loop before Waitkey (2000), otherwise will appear the Flash back; 2. There is a decoding problem with the webcam video.

--------------------------------------"program description"-------------------------------------------
//		Program Description: OPENCV Computer Vision Library Getting Started learning
//		Program Description: Desktop using OPENCV external USB camera, read in video and display
/		dev Test operating system: Windows 7 64bit
//		IDE version for development test: Visual Studio
//		Development Test OPENCV version:  2.4.9
//		October 2017 Created by @ Fireman1994
//-------------------------------------------------------------------------------------------- ----

#include "cv.h"
#include "highgui.h"
#include "iostream"
using namespace std;

int main (int argc,char* argv[])
{
	cvcapture* cap;
	Cap=cvcapturefromcam (0);
	if (!cap)
	{
		cout<< "Create Camera Capture Error" <<endl;
		System ("pause");
		Exit ( -1);
	}
	Cvnamedwindow ("img", 1);
	iplimage* img;
	Before entering the loop, wait for a period of time for the camera to initialize, otherwise initialization is not completed, will flash out of the program
	Cvwaitkey (a);
	while (1)
	{
		img=cvqueryframe (CAP);//read-in video decode
		if (!img) break
		;
	
		Cvshowimage ("IMG", IMG);
		Cvwaitkey (3);
	}
	Cvreleasecapture (&CAP);
	Cvdestroyallwindows ();
	Cvreleaseimage (&img);
	return 0;
}