use*_*330 11 c++ linux performance opencv screenshot
我正试图找到一种快速的截屏方式(如30 fps或以上),以便在c ++中使用opencv
我在网上找到的所有信息都涉及到windows.h或者速度太慢.
有人能为我提供一些实现这一目标的代码,或者至少指出我正确的方向,这样我就能解决这个问题吗？
Bra*_*don 12
您可以使用它将屏幕截图变为原始像素结构.将它传递给OpenCV以及Width&Height&BitsPerPixel,你应该很好.
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <cstdint>
#include <cstring>
#include <vector>
void ImageFromDisplay(std::vector<uint8_t>& Pixels, int& Width, int& Height, int& BitsPerPixel)
{
Display* display = XOpenDisplay(nullptr);
Window root = DefaultRootWindow(display);
XWindowAttributes attributes = {0};
XGetWindowAttributes(display, root, &attributes);
Width = attributes.width;
Height = attributes.height;
XImage* img = XGetImage(display, root, 0, 0 , Width, Height, AllPlanes, ZPixmap);
BitsPerPixel = img->bits_per_pixel;
Pixels.resize(Width * Height * 4);
memcpy(&Pixels[0], img->data, Pixels.size());
XDestroyImage(img);
XCloseDisplay(display);
}
然后使用它OpenCV,你可以做:
int main()
{
int Width = 0;
int Height = 0;
int Bpp = 0;
std::vector<std::uint8_t> Pixels;
ImageFromDisplay(Pixels, Width, Height, Bpp);
if (Width && Height)
{
Mat img = Mat(Height, Width, Bpp > 24 ? CV_8UC4 : CV_8UC3, &Pixels[0]); //Mat(Size(Height, Width), Bpp > 24 ? CV_8UC4 : CV_8UC3, &Pixels[0]);
namedWindow("WindowTitle", WINDOW_AUTOSIZE);
imshow("Display window", img);
waitKey(0);
}
return 0;
}
基于@ abc的答案,我想出了以下内容,使用MIT的X共享内存扩展.
@ abc的例子以120-180 fps运行并使用~40%的Titan X(Maxwell).以下以15000 fps运行并使用80%的Titan X.
注释掉break;内部循环内部的语句也可以不间断地运行它.
使用@ abc类的版本:
// g++ screena.cpp -o screena -lX11 -lXext -Ofast -mfpmath=both -march=native -m64 -funroll-loops -mavx2 `pkg-config opencv --cflags --libs` && ./screena
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/XShm.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <opencv2/opencv.hpp> // This includes most headers!
#include <time.h>
#define FPS(start) (CLOCKS_PER_SEC / (clock()-start))
struct ScreenShot{
ScreenShot(uint x, uint y, uint width, uint height):
x(x), y(y), width(width), height(height){
display = XOpenDisplay(nullptr);
root = DefaultRootWindow(display);
XGetWindowAttributes(display, root, &window_attributes);
screen = window_attributes.screen;
ximg = XShmCreateImage(display, DefaultVisualOfScreen(screen), DefaultDepthOfScreen(screen), ZPixmap, NULL, &shminfo, width, height);
shminfo.shmid = shmget(IPC_PRIVATE, ximg->bytes_per_line * ximg->height, IPC_CREAT|0777);
shminfo.shmaddr = ximg->data = (char*)shmat(shminfo.shmid, 0, 0);
shminfo.readOnly = False;
if(shminfo.shmid < 0)
puts("Fatal shminfo error!");;
Status s1 = XShmAttach(display, &shminfo);
printf("XShmAttach() %s\n", s1 ? "success!" : "failure!");
init = true;
}
void operator() (cv::Mat& cv_img){
if(init)
init = false;
XShmGetImage(display, root, ximg, 0, 0, 0x00ffffff);
cv_img = cv::Mat(height, width, CV_8UC4, ximg->data);
}
~ScreenShot(){
if(!init)
XDestroyImage(ximg);
XShmDetach(display, &shminfo);
shmdt(shminfo.shmaddr);
XCloseDisplay(display);
}
Display* display;
Window root;
XWindowAttributes window_attributes;
Screen* screen;
XImage* ximg;
XShmSegmentInfo shminfo;
int x, y, width, height;
bool init;
};
int main(){
ScreenShot screen(0, 0, 1920, 1080);
cv::Mat img;
for(uint i;; ++i){
double start = clock();
screen(img);
if(!(i & 0b111111))
printf("fps %4.f spf %.4f\n", FPS(start), 1 / FPS(start));
break;
}
cv::imshow("img", img);
cv::waitKey(0);
}
"裸"版:
// g++ xshm2.c -o xshm2 -lX11 -lXext `$cv`-Ofast -mfpmath=both -march=native -m64 -funroll-loops -mavx2 && ./xshm2
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/XShm.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <opencv2/opencv.hpp> // This includes most headers!
#include <time.h>
#define FPS(start) (CLOCKS_PER_SEC / (clock()-start))
// Using one monitor DOESN'T improve performance! Querying a smaller subset of the screen DOES
const uint WIDTH = 1920>>0;
const uint HEIGHT = 1080>>0;
// -------------------------------------------------------
int main(){
Display* display = XOpenDisplay(NULL);
Window root = DefaultRootWindow(display); // Macro to return the root window! It's a simple uint32
XWindowAttributes window_attributes;
XGetWindowAttributes(display, root, &window_attributes);
Screen* screen = window_attributes.screen;
XShmSegmentInfo shminfo;
XImage* ximg = XShmCreateImage(display, DefaultVisualOfScreen(screen), DefaultDepthOfScreen(screen), ZPixmap, NULL, &shminfo, WIDTH, HEIGHT);
shminfo.shmid = shmget(IPC_PRIVATE, ximg->bytes_per_line * ximg->height, IPC_CREAT|0777);
shminfo.shmaddr = ximg->data = (char*)shmat(shminfo.shmid, 0, 0);
shminfo.readOnly = False;
if(shminfo.shmid < 0)
puts("Fatal shminfo error!");;
Status s1 = XShmAttach(display, &shminfo);
printf("XShmAttach() %s\n", s1 ? "success!" : "failure!");
cv::Mat img;
for(int i; ; i++){
double start = clock();
XShmGetImage(display, root, ximg, 0, 0, 0x00ffffff);
img = cv::Mat(HEIGHT, WIDTH, CV_8UC4, ximg->data);
if(!(i & 0b111111))
printf("fps %4.f spf %.4f\n", FPS(start), 1 / FPS(start));
break;
}
cv::imshow("img", img);
cv::waitKey(0);
XShmDetach(display, &shminfo);
XDestroyImage(ximg);
shmdt(shminfo.shmaddr);
XCloseDisplay(display);
puts("Exit success!");
}
我使用 Brandon 的回答制作了一个更快的基于仿函数的屏幕截图代码：
#include <opencv2/opencv.hpp>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
class ScreenShot
{
Display* display;
Window root;
int x,y,width,height;
XImage* img{nullptr};
public:
ScreenShot(int x, int y, int width, int height):
x(x),
y(y),
width(width),
height(height)
{
display = XOpenDisplay(nullptr);
root = DefaultRootWindow(display);
}
void operator() (cv::Mat& cvImg)
{
if(img != nullptr)
XDestroyImage(img);
img = XGetImage(display, root, x, y, width, height, AllPlanes, ZPixmap);
cvImg = cv::Mat(height, width, CV_8UC4, img->data);
}
~ScreenShot()
{
if(img != nullptr)
XDestroyImage(img);
XCloseDisplay(display);
}
};
以下是您将如何在循环中使用它（按 退出q）：
int main()
{
ScreenShot screen(0,0,1920,1080);
cv::Mat img;
while(true)
{
screen(img);
cv::imshow("img", img);
char k = cv::waitKey(1);
if (k == 'q')
break;
}
}
这在我的机器上快了大约 39%。