c++ - 使用套接字发送 Iplimage

Question

我正在尝试从通过 USB 连接到 Raspberry Pi 的罗技高清摄像头捕获帧，RP 正在运行 arch linux，我正在使用 OpenCV C api 和 TCP 客户端。

TCP服务器在ubuntu下运行c++(QT)

我将 frame->imageData 存储在缓冲区中，然后将数据发送到缓冲区中。

这是一个概念证明，我可以将一个帧保存到缓冲区，然后从缓冲区重建一个新帧，它是 tmpbuffer，实际上这段代码运行完美:

CvCapture *capture = cvCaptureFromCAM(1);
cvNamedWindow( "mywindow", CV_WINDOW_AUTOSIZE );
    int i =1;

   while ( 1 ) {
     // Get one frame
     IplImage* frame = cvQueryFrame( capture );
     CvSize size;
     size.height = 480;
  size.width = 640;
     IplImage* tmpframe = cvCreateImageHeader(size, IPL_DEPTH_8U, 3); //create a new frame
     if ( !frame ) {
       //fprintf( stderr, "ERROR: frame is null...\n" );
       getchar();
       break;
     }else
     {
         //std::cout<<i<<std::endl;
         char buffer[frame->imageSize];
         snprintf(buffer,frame->imageSize,"%s",frame->imageData);
         //printf("frame->height= %s\n",buffer);

         tmpframe->imageData = buffer;
         printf("data %s\n",tmpframe->imageData);

         //snprintf(IDbuffer,10,"%d",frame->ID);
         //printf("frame->ID= %s\n",IDbuffer);
         i++;
     }
     cvShowImage( "mywindow", tmpframe );

这是我的 client.c 文件:

#include <opencv/cv.h>
 #include <opencv/highgui.h>
 #include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>


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

int main(int argc,char *argv[])
{

int sockfd,portno,n;
 struct sockaddr_in serv_addr;
 struct hostent *server;


 if(argc <3)
 {
  fprintf(stderr,"usage %s hostname portname 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,&serv_addr,sizeof(serv_addr)) < 0)
 {
  error("ERROR CONNECTING");
 }
    CvCapture *capture = cvCaptureFromCAM(1);
       // Show the image captured from the camera in the window and repeat
        int i =1;

       while ( 1 ) {
         // Get one frame
         IplImage* frame = cvQueryFrame( capture );
         if ( !frame ) {
           //fprintf( stderr, "ERROR: frame is null...\n" );
           getchar();
           break;
         }else
         {
             i++;
         }

         char *msg = frame->imageData;
         char buffer[frame->imageSize];
         bzero (buffer,frame->imageSize);
         snprintf(buffer,frame->imageSize,"%s",msg);
 n=write(sockfd,buffer,frame->imageSize);
 if(n <0)
 {
  error("ERROR READING FROM SOCKET");
 }
 //printf("%s\n",buffer);


 }
return 0;
}

这就是我在服务器上接收数据的方式:

void HostConnector::readyRead()
{
    QByteArray Data = socket->readAll();

    CvSize size;
    size.height = 480;
    size.width = 640;
    IplImage *frame = cvCreateImageHeader(size, IPL_DEPTH_8U, 3);


    frame->imageData = Data.data();
    cvShowImage( "mywindow", frame );

}

但是服务器崩溃了!! 段错误在

cvShowImage( "mywindow", frame );

Answer 1

我在没有仔细检查代码的情况下看到的两个问题:

• 您正在使用 printf(3) 风格的函数来格式化二进制数据。那是错误的^TM。生成的字符串的长度将与图像的长度不同，二进制数据可能在中间有零字节，或者没有零终止符。
• 您正在其范围之外使用临时缓冲区 (char buffer[frame->imageSize]) - 这可能是段错误的原因。