用qt+opencv， 写一个电脑录屏的示例代码， 保存格式 h264

可以的，以下是示例代码：

#include "opencv2/opencv.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/video.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
#include <chrono>
#include <ctime>

using namespace cv;
using namespace std;

int main()
{
    VideoCapture cap(0);
    if (!cap.isOpened())
    {
        std::cout << "Cannot open Camera" << std::endl;
        return -1;
    }

    int frame_width = static_cast<int>(cap.get(CAP_PROP_FRAME_WIDTH));
    int frame_height = static_cast<int>(cap.get(CAP_PROP_FRAME_HEIGHT));

    VideoWriter writer;
    double fps = 25.0;
    int codec = VideoWriter::fourcc('H', '2', '6', '4');
    writer.open("output.h264", codec, fps, Size(frame_width, frame_height), true);
    if (!writer.isOpened())
    {
        std::cout << "Cannot open file" << std::endl;
        return -1;
    }

    std::cout << "Press q to stop recording" << std::endl;

    while (true)
    {
        Mat frame;
        cap >> frame;
        writer << frame;

        imshow("Frame", frame);

        char c = static_cast<char>(waitKey(1));
        if (c == 'q' || c == 'Q')
            break;
    };

    cap.release();
    writer.release();
    destroyAllWindows();

    std::cout << "Recording complete" << std::endl;

    return 0;
}

这是一个使用OpenCV和Qt编写的电脑录屏示例程序，可以将摄像头捕获的视频流编码为H.264格式并保存到本地文件。希望这个示例程序可以帮助你实现你的目标。