我想在两个 Linux 进程之间共享一个 CvMat 对象(OpenCV 库中的矩阵),为此我使用共享内存。一个进程(服务器)将从网络摄像头捕获一帧(矩阵),将其转换为灰度,使用共享内存共享它并在屏幕上显示该帧。另一个进程(客户端)将读取共享帧并执行一些操作。请参阅下面的代码。
问题似乎是客户端没有读取信息,因为“行”和“列”为零(或者服务器没有写入共享内存)。无论如何,我没有收到任何错误消息,我不知道我做错了什么。任何想法?
非常感谢!
这是服务器的代码:
#include <iostream>
#include <cv.h>
#include <highgui.h>
using namespace std;
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include "2cam.h"
int sizeofmat(CvMat *mat) {
return mat->rows * mat->cols * CV_ELEM_SIZE(mat->type);
}
int main() {
int shmid;
key_t key = 5678;
CvMat *vdisp = cvCreateMat(240, 320, CV_8U);
const size_t vdispsize = sizeofmat(vdisp);
CvMat *s = cvCreateMat(240, 320, CV_8U);
CvMat stub;
CvSize imageSize = cvSize(320, 240);
IplImage *color = cvCreateImage(imageSize, 8, 3);
IplImage *gray = cvCreateImage(imageSize, 8, 1);
/* Create the segment */
if ((shmid = shmget(key, vdispsize, IPC_CREAT | 0666)) < 0) {
perror("shmget");
exit(1);
}
/* Attach the segment to our data space */
if ((vdisp = (CvMat *)shmat(shmid, NULL, 0)) == (CvMat *)-1) {
perror("shmat");
exit(1);
}
/* Put CvMat into the memory to be read for other processes */
s = vdisp;
/* Create camera */
Camera c("/dev/video0", 320, 240, 30);
while (1) {
/* Get one frame */
c.Update();
c.toIplImage(color);
/* Convert color frame to grayscale */
cvCvtColor(color, gray, CV_BGR2GRAY);
/* Get matrix from the gray frame and write the matrix in shared memory*/
s = cvGetMat(gray, &stub, 0, 0);
/* Show frame */
cvNamedWindow("result", CV_WINDOW_AUTOSIZE);
cvShowImage("result", s);
/* Wait for escape key */
if ((cvWaitKey(10) & 255) == 27)
break;
}
/* free memory */
cvDestroyWindow("result");
cvReleaseImage(&color);
cvReleaseImage(&gray);
//cvReleaseMat(&vdisp);
//cvReleaseMat(&s);
return 0;
}
这是客户的代码:
#include <iostream>
#include <cv.h>
#include <highgui.h>
using namespace std;
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
int sizeofmat(CvMat *mat) {
return mat->rows * mat->cols * CV_ELEM_SIZE(mat->type);
}
int main() {
int shmid;
key_t key = 5678;
CvMat *vdisp = cvCreateMat(240, 320, CV_8U);
const size_t vdispsize = sizeofmat(vdisp);
CvMat *s = cvCreateMat(240, 320, CV_8U);
/* Locate the segment */
if ((shmid = shmget(key, vdispsize, 0666)) < 0) {
perror("shmget");
exit(1);
}
/* Now we attach the segment to our data space */
if ((vdisp = (CvMat *)shmat(shmid, NULL, 0)) == (CvMat *) -1) {
perror("shmat");
exit(1);
}
s = vdisp;
cout << "rows: " << s->rows << endl;
cout << "cols: " << s->cols << endl;
return 0;
}