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OpenCV实现简单录屏功能

运维开发网 https://www.qedev.com 2022-01-20 10:26 出处:网络 作者: 蓬
本文实例为大家分享了OpenCV实现简单录屏功能的具体代码,供大家参考,具体内容如下

本文实例为大家分享了OpenCV实现简单录屏功能的具体代码,供大家参考,具体内容如下

OpenCV中VideoCapture和VideoWriter用于读写视频文件,这里的录屏功能用到VideoWriter,用于将捕获的屏幕的每一帧数据保存到视频文件。

VideoWriter写视频文件的步骤

1、bool open(const String& filename, int fourcc, double fps,Size frameSize, bool isColor = true);

2、void write(InputArray image);或者VideoWriter& operator << (const Mat& image);

3、void release();

下列代码用于获取屏幕的截图

int width = GetSystemMetrics(SM_CXSCREEN);
int height = GetSystemMetrics(SM_CYSCREEN);
HDC hdcScreen = GetDC(NULL);
HDC hdcMemDC = CreateCompatibleDC(hdcScreen);
HBITMAP hbmScreen = CreateCompatibleBitmap(hdcScreen, width, height);

BITMAPINFO bi;
bi.bmiHeader.biSizehCgSr = sizeof(bi.bmiHeader);
bi.bmiHeader.biWidth = width;
bi.bmiHeader.biHeight = height;
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 24;
bi.bmiHeader.biCompression = BI_RGB;
bi.bmiHeader.biSizeImage = 0;
bi.bmiHeader.biXPelsPerMeter = 0;
bi.bmiHeader.biYPelsPerMeter = 0;
bi.bmiHeader.biClrUsed = 0;
bi.bmiHeader.biClrImportant = 0;
SelectObject(hdcMemDC, hbmScreen);
int lineBytes = ((width * bi.bmiHeader.biBitCount + 31) / 32) * 4;//每行字节数必须是4字节的整数倍
int bmpSize = lineBytes * height;
char* lpbitmap = new char[bmpSize];
BitBlt(hdcMemDC, 0, 0, width, height, hdcScreen, 0, 0, SRCCOPY);
GetDIBits(hdcMemDC, hbmScreen, 0, height, lpbitmap, &bi, DIB_RGB_COLORS);

lpbitmap为屏幕的像素颜色数据,下列代码将lpbitmap作为一帧写到视频中(假设VideoWriter为已正常打开的VideoWriter实例)

cv::Mat bmpMat(height, width, CV_8UC3);
for (int i = 0; i < height; i++)
{
  int srcIndex = (height-i-1) * lineBytes;
  int destIndex = i * width * 3;
  memcpy(&bmpMat.data[destIndex],&lpbitmap[srcIndex],width*3);
}
videoWriter.write(bmpMat);//或videoWriter << bmpMat;

因为lpbitmap中的数据是从左下角到右上角排列,而视频帧图像的数据是从左上角到右下角排列,所以要将数据按行上下翻转,即lpbitmap第一行对应视频图像的最后一行。另外BMP图像数据每行的字节数必须是4字节的整数倍,而写入视频的Mat数据没有这个要求,即每行数据大小是图像实际宽度乘以每个颜色占用的字节数,所以实际每行拷贝的数据是width*3节字。

下面是一段测试代码,这里只录制100帧,实际使用中http://www.cppcns.com可通过命令行参数、快捷键或按钮等自行决定开始和结束时间,帧率这里也设为固定的25,其实也应该根据具体形况设定合适的值。最后别忘了将opencv_ffmpegXXX.dll文件放到可执行文件目录下。

#include<windows.h>
#include"opencv2/opencv.hpp"
int main()
{

  cv::VideoWriter videoWriter;
  double fps = 25;
  int codec = cv::VideoWriter::fourcc('m', 'p', '4', 'v');
  int width = GetSystemMetrics(SM_CXSCREEN);
  int height = GetSystemMetrics(SM_CYSCREEN);

  time_t seconds = time(0);
  int s = seconds % 60;
  int m = (seconds % 3600) / 60;
  int h = (seconds % (3600 * 24)) / 3600 + 8;
  char timeBuf[128] = { 0 };
  sprintf_s(timeBuf, "CaptureScreen-%d-%d-%d.mp4", h, m, s);
  cv::String filePath = timeBuf;
  videoWriter.open(filePath, codec, fps, cv::Size(width, height), true);
  if (!videoWriter.isOpened())
  {
    return -1;
  }

  HDC hdcScreen = GetDC(NULL);
  HDC hdcMemDC = CreateCompatibleDC(hdcScreen);
  HBITMAP hbmScreen = CreateCompatibleBitmap(hdcScreen, width, height);

  BITMAPINFO bi;
  bi.bmiHeader.biSize = sizeof(bi.bmiHeader);
  bi.bmiHeader.biWidth = width;
  bi.bmiHeader.biHeight = height;
  bi.bmiHeader.hCgSrbiPlanes = 1;
  bwww.cppcns.comi.bmiHeader.biBitCount = 24;
  bi.bmiHeader.biCompression = BI_RGB;
  bi.bmiHeader.biSizeImage = 0;
  bi.bmiHeader.biXPelsPerMeter = 0;
  bi.bmiHeader.biYPelsPerMeter = 0;
  bi.bmiHeader.biClrUsed = 0;
  bi.bmiHeader.biClrImportant = 0;
  SelectObject(hdcMemDC, hbmScreen);

  int lineBytes = ((width * bi.bmiHeader.biBitCount + 31) / 32) * 4;
  int bmpSize = lineBytes * height;
  char* lpbitmap = new char[bmpSize];
  cv::Mat bmpMat(height, width, CV_8UC3);
  for (int i=0;i<100;i++)
  {
    if (BitBlt(hdcMemDC, 0, 0, width, height, hdcScreen, 0, 0, SRCCOPY))
    {
      GetDIBits(hdcMemDC, hbmScreen, 0, height, lpbitmap, &bi, DIB_RGB_COLORS);
      for (int i = 0; i < height; i++)
      {
        int srcIndex = (height-i-1) * lineBytes;
        int destIndex = i * width * 3;
        memcpy(&bmpMathCgSr.data[destIndex],&lpbitmap[srcIndex],width*3);
      }
      videoWriter.write(bmpMat);//videoWriter << bmpMat;
    }
  }
  delete[] lpbitmap;
  if (videoWriter.isOpened())
  {
    videoWriter.release();
  }
  return 0;
}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持我们。

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