I am trying to capture frames from a Logitech HD cam connected to a Raspberry Pi through usb, the RP is running arch linux and I am using OpenCV C api and a TCP client.
The TCP server is running c++(QT) under ubuntu.
I am storing the frame->imageData in a buffer and then send the data in the buffer.
this is a proof of concept that this idea works fine where tmpframe should be the new frame constructed on the server:
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 );
actually this code is running perfectly,
Here is my client.c file:
#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;
//char buffer[999999];
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++;
}
//bzero (buffer,999999);
//strncpy(buffer,frame->imageData,sizeof(frame->imageData) -1);
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;
}
and this is how I am receiving data on my server:
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 );
}
But the server is crashing !!
a segmentation fault at cvShowImage( "mywindow", frame );
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