通过套接字发送C++ OpenCV图像

Question

通过套接字发送C++ OpenCV图像

16

我正试图使用OpenCV和sockets实现一个流媒体服务。服务器端加载给定的图像并将其通过socket发送到客户端，客户端接收并显示该图像。然而，我在发送图像数据和在客户端上重建图像时遇到了很多问题。以下是我迄今为止编写的代码：

图像发送方：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    if (argc < 3) {
       fprintf(stderr,"usage %s hostname port\n", argv[0]);
       exit(0);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }
    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, 
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) 
        error("ERROR connecting");

    Mat image;
    image = imread(argv[3], CV_LOAD_IMAGE_COLOR);
    if(! image.data )                              // Check for invalid input
    {
        cout <<  "Could not open or find the image" << std::endl ;
        return -1;
    }

    n = write(sockfd,image.data,image.total()*image.channels());
    if (n < 0) 
         error("ERROR writing to socket");
    close(sockfd);

    namedWindow( "Client", CV_WINDOW_AUTOSIZE );// Create a window for display.
    imshow( "Client", image );  
    waitKey(0);
    return 0;
}

图像接收器：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
     int sockfd, newsockfd, portno;
     socklen_t clilen;
     char buffer[1024];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     if (argc < 2) {
         fprintf(stderr,"ERROR, no port provided\n");
         exit(1);
     }
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0) 
        error("ERROR opening socket");
     bzero((char *) &serv_addr, sizeof(serv_addr));
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, 
                 (struct sockaddr *) &cli_addr, 
                 &clilen);
     if (newsockfd < 0) 
          error("ERROR on accept");
     bzero(buffer,1024);

     n = read(newsockfd,buffer,1023);
     if (n < 0) error("ERROR reading from socket");

     Mat image(690,690,CV_8UC3,*buffer);
     imwrite("/home/securitas/images/prova.jpg",image);
     close(newsockfd);
     close(sockfd);

     namedWindow( "Server", CV_WINDOW_AUTOSIZE );// Create a window for display.
     imshow( "Server", image );  
     waitKey(0);
     return 0; 
}

我在客户端只收到了一张黑色的图片，没有其他任何内容。需要帮助吗？

- user2938976

5个回答

3

bytes = send(clientSock, frame.data, imgSize, 0));

在Visual Studio 12中，这个语句出现了错误。它说.. 错误: "uchar *"类型的参数与"const char *"类型的参数不兼容，在""frame.data""处。

- user3165224

1

在 Microsoft Visual Studio 2012 中，sockData[imgSize] 下的红色线条表示表达式必须具有常量值。然后我将 int imgSize 更改为 const int imgSize。它仍然显示相同的问题。

 Mat img = Mat::zeros(100,100, CV_8UC3);
 const int imgSize = img.total()*img.elemSize();
 uchar sockData[imgSize];

- user5473110

1

缓冲区溢出。我不确定图像的格式和大小是否相同，因此您应该诚实地序列化您的Mat，类似于这里。

- user1190294

1024不够吗？或者你是指发送方？那我该填什么呢？9999999？ - user2938976

1

Haris的回答是正确的，也对我有用。然而，与那个服务器端代码（从uchar数据构建图像）不同，你还可以使用更短的形式：

int  imgSize = img.total()*img.elemSize();
uchar sockData[imgSize];

for (int i = 0; i < imgSize; i += bytes) {
    if ((bytes = recv(connectSock, sockData +i, imgSize  - i, 0)) == -1)
        quit("recv failed", 1);
}

// change the last loop to below statement
Mat img(Size(HEIGHT, WIDTH), CV_8UC3, socketData);

- Sida

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Haris · Accepted Answer

获取Mat.data并直接发送到套接字，数据顺序为BGR BGR BGR....在接收端假设您知道图像的大小。接收后，只需将接收到的缓冲区（BGR BGR ...数组）分配给Mat。

客户端：

Mat frame;
frame = (frame.reshape(0,1)); // to make it continuous

int  imgSize = frame.total()*frame.elemSize();

// Send data here
bytes = send(clientSock, frame.data, imgSize, 0))

服务器:-

Mat  img = Mat::zeros( height,width, CV_8UC3);
int  imgSize = img.total()*img.elemSize();
uchar sockData[imgSize];

//Receive data here

for (int i = 0; i < imgSize; i += bytes) {
    if ((bytes = recv(connectSock, sockData +i, imgSize  - i, 0)) == -1)  {
        quit("recv failed", 1);
    }
}

// Assign pixel value to img
int ptr=0;
for (int i = 0;  i < img.rows; i++) {
    for (int j = 0; j < img.cols; j++) {                                     
       img.at<cv::Vec3b>(i,j) = cv::Vec3b(sockData[ptr+ 0],sockData[ptr+1],sockData[ptr+2]);
       ptr=ptr+3;
    }
}