bool VideoCapture::push_back(int device, cv::Ptr<_VideoCaptureInterface> cam){
	if(!cam->open(device)){
		return false;
	}
	cam_interface.push_back(cam);
	return true;
}
bool VideoCapture::push_back(const std::string& filename, cv::Ptr<_VideoCaptureInterface> cam){
	if(!cam->open(filename)){
		return false;
	}
	cam_interface.push_back(cam);
	return true;
}