无法在Linux中使用OpenCV打开相机

我现在在linux上使用OpenCV 2.4.3。在我的/dev/中有一个叫video0的设备，它可以很好地工作。

目前，我正在使用以下代码来尝试访问相机。这段代码是在qtcreator中编写的，并使用qmake进行编译，以包含必要的库。对于OpenCV库，我在我的机器上下载了源代码，并按照网站上的说明进行了编译。

+ + main.cpp:

#include <iostream>
#include <opencv2/opencv.hpp>
#include <cstdlib>
int main(int argc, char** argv) {
    int cameraNumber = 0;
    if (argc>1)
        cameraNumber = atoi(argv[1]);
    cv::VideoCapture camera;
    camera.open(cameraNumber);
    if(!camera.isOpened()) {
        std::cerr<<"Error opening camera"<<std::endl;
        exit(1);
    }
    camera.set(CV_CAP_PROP_FRAME_WIDTH,640);
    camera.set(CV_CAP_PROP_FRAME_HEIGHT,480);
    while(true) {
        cv::Mat cameraFrame;
        camera>>cameraFrame;
        if (cameraFrame.empty()){
            std::cerr<<"No frame read from camera"<<std::endl;
            exit(1);
        }
        imshow("Camera",cameraFrame);
        char keypress = cv::waitKey(20);
        if (keypress==27) {
            break;
        }
    }
    return 0;
}

+ + test.pro

TEMPLATE = app
CONFIG += console
CONFIG -= app_bundle
CONFIG -= qt
SOURCES += main.cpp
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/release/ -lopencv_core
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/debug/ -lopencv_core
else:unix: LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/ -lopencv_core
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/release/ -lopencv_highgui
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/debug/ -lopencv_highgui
else:unix: LIBS += -L$$PWD/../../../../opt/OpenCV-2.4.3/lib/ -lopencv_highgui
INCLUDEPATH += $$PWD/../../../../opt/OpenCV-2.4.3/include
DEPENDPATH += $$PWD/../../../../opt/OpenCV-2.4.3/include

但是运行程序时输出Error opening camera并退出，说明相机没有打开成功。我已经谷歌了一段时间，没有找到任何可能的解决方案来解决这个问题。谁能给我一些建议如何解决这个问题?谢谢!