OpenCv在Qt中的使用

1.使用OpenCV进行打开摄像头并进行录像

    CvCapture *capture;
    IplImage *frame;
    QImage *qImg;
    QTimer *timer;
    capture = cvCaptureFromCAM(0);
    cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_WIDTH,320);
    cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_HEIGHT,240);
    if(capture)
    {
        QMessageBox::information(this,"Information","successful!");
        if (capture)
        {
            frame = cvQueryFrame(capture);
            if (frame)
                this->resize(frame->width,frame->height);
            qImg = new QImage(QSize(frame->width,frame->height),QImage::Format_RGB888);
            iplImg = cvCreateImageHeader(cvSize(frame->width,frame->height),8,3);
            iplImg->imageData = (char*)qImg->bits();
            timer = new QTimer(this);
            timer->setInterval(30);
            connect(timer,SIGNAL(timeout()),this,SLOT(nextFrame()));
            timer->start();
            writer = cvCreateVideoWriter("out.avi",CV_FOURCC('D', 'I', 'V', 'X'),10,
                                         cvSize(frame->width,frame->height),1);
            isCamera = true;
        }
    }
    else
    {
        QMessageBox::information(this,"Information","Sorry,fail!");
        isCamera = false;
    }
void openCV::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
    if(isCamera == true)
    {
        painter.drawImage(QPoint(0,0),*qImg);
    }
    else
    {

    }
}
void openCV::nextFrame()
{
    frame = cvQueryFrame(capture);

    if (frame)
    {
        if (frame->origin == IPL_ORIGIN_TL)
        {
            cvCopy(frame,iplImg,0);
        }
        else
        {
            cvFlip(frame,iplImg,0);
        }
        cvCvtColor(iplImg,iplImg,CV_BGR2RGB);
        cvWriteFrame(writer,frame);
        this->update();
    }
}

在编译的目录下就有out.avi这个视频文件，要打开视频文件如下：

    CvCapture *capture;
    IplImage *frame;
    QImage *qImg;
    QTimer *timer;
    capture = cvCaptureFromFile("out.avi");
    if (capture)
    {
        frame = cvQueryFrame(capture);
        if (frame)
            this->resize(frame->width,frame->height);
        qImg = new QImage(QSize(frame->width,frame->height),QImage::Format_RGB888);
        iplImg = cvCreateImageHeader(cvSize(frame->width,frame->height),8,3);
        iplImg->imageData = (char*)qImg->bits();
        timer = new QTimer(this);
        timer->setInterval(30);
        connect(timer,SIGNAL(timeout()),this,SLOT(nextFrame()));
        timer->start();

        isCamera = true;
    }
    else
    {
        QMessageBox::information(this,"Information","Sorry,fail!");
        isCamera = false;
    }
void openCV::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
    if(isCamera == true)
    {
        painter.drawImage(QPoint(0,0),*qImg);
    }
    else
    {

    }
}
void openCV::nextFrame()
{
    frame = cvQueryFrame(capture);

    if (frame)
    {
        if (frame->origin == IPL_ORIGIN_TL)
        {
            cvCopy(frame,iplImg,0);
        }
        else
        {
            cvFlip(frame,iplImg,0);
        }
        cvCvtColor(iplImg,iplImg,CV_BGR2RGB);
        this->update();
    }
}
 这里面有个问题，第一，程序无法运行，经检查是 
     
      cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_WIDTH,320);   
          cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_HEIGHT,240);
 cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_WIDTH,320);
     cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_HEIGHT,240);

 这两句话的问题。查了一圈资料，貌似不支持。将其屏蔽！注释掉，程序就能运行了！
 第二，变量isCamera应该申明成为全局变量。按照原博客里的申明方法根本不可运行。将其申明为：static bool  isCamera = false；这句话放在头文件的外面！！！
 其他部分参照下面程序即可！
 第一，有时候运行程序会卡住，直接出不来图像。在MyWidget的析构函数中增加cvReleaseImage(&frame)好了很多。另外定时器的间隔时间调40ms、50ms会好点。我的电脑内存是4G，当内存占用1300多M时，运行程序卡的几率很大。重启后卡的几率就变小了。 不知道为什么？？
 第二，每次运行程序时，在显示图片之前会有警告。mmap：无效的参数
  munmap：无效的参数
 munmap；无效的参数  。