In my code, I want to run a Videocapture in a separate pthread continuously, while the main thread will act as a socket server to communicate to any client (or vice versa).
When the client communicates to the server, the server will immediately send the latest Videocapture frame to the client and close the connection and again wait for another connection.
I am currently using OpenCV 2.3.0 in mingw32 environment.
After looking some possible solutions on StackOverflow, I tried following them, but, however may I place the OpenCV variables either locally or globally or swapping the threads i.e. keeping Videocapture thread in main thread or in the 2nd thread, the program just hangs silently at the mutex locked area of the VideoCapture thread when the client gets connected.
I suppose this is happening when the server thread starts locking the mutex after connecting to a client.
Any reasoning or possible solution will be highly appreciated. Also, I am using prebuilt OpenCV version 2.3.0 and I need the code to be cross platform. In any case, if it points to a bug, I can obviously switch to some other version.
Server code
mynet.h
#ifndef __MYNET__
#define __MYNET__
#ifdef _WIN32
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0501 /* Windows XP. */
#endif
#include <winsock2.h>
#include <Ws2tcpip.h>
#else
/* Assume that any non-Windows platform uses POSIX-style sockets instead. */
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h> /* Needed for getaddrinfo() and freeaddrinfo() */
#include <unistd.h> /* Needed for close() */
#endif
int sockInit(void)
{
#ifdef _WIN32
WSADATA wsa_data;
return WSAStartup(MAKEWORD(1,1), &wsa_data);
#else
return 0;
#endif
}
int sockQuit(void)
{
#ifdef _WIN32
return WSACleanup();
#else
return 0;
#endif
}
/* Note: For POSIX, typedef SOCKET as an int. */
#ifndef _WIN32
typedef int SOCKET;
#else
typedef unsigned int SOCKET;
#endif
int sockClose(SOCKET sock)
{
int status = 0;
#ifdef _WIN32
status = shutdown(sock, SD_BOTH);
if (status == 0) { status = closesocket(sock); }
#else
status = shutdown(sock, SHUT_RDWR);
if (status == 0) { status = close(sock); }
#endif
return status;
}
#if(defined(_WIN32) || defined(WIN32))
#include <windows.h>
#define mysleep(x) Sleep((x))
#else
#include <unistd.h>
#define mysleep(x) usleep((x)*1000)
#endif
#endif
netserver.cpp
#define _GLIBCXX_USE_CXX11_ABI 0
#undef _GLIBCXX_DEBUG
#include "../mynet.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <pthread.h>
using namespace cv;
Mat frame(120, 160, CV_8UC3);;
pthread_mutex_t mutex;
pthread_t thread;
void *myfunc(void *threadid)
{
int n;
int listenfd = 0,connfd = 0;
struct sockaddr_in serv_addr;
unsigned char sendBuff[160*120*3];
Mat hereframe;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
printf("socket retrieve success\n");
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(5000);
bind(listenfd, (struct sockaddr*)&serv_addr,sizeof(serv_addr));
if(listen(listenfd, 10) == -1)
{
printf("Failed to listen\n");
}
else
{
connfd = accept(listenfd, (struct sockaddr*)NULL,NULL); // accept awaiting request
if(connfd<=0) printf("Something went wrong with write()! %s\n", strerror(errno));
else
{
while(1)
{
printf("Got client...\n");
pthread_mutex_lock (&mutex);
printf("Copying data...\n");
frame.copyTo(hereframe);
pthread_mutex_unlock (&mutex);
printf("Hereframe size: %dX%d\n", hereframe.rows, hereframe.cols);
memcpy(sendBuff, hereframe.data, 120*160*3);
printf("Sending data...\n");
n = send(connfd, (char*)sendBuff, 120*160*3,0);
if(n<0) printf("Something went wrong with write()! %s\n", strerror(errno));
printf("Closing client after writing %d bytes...\n", n);
printf("Closed...\n");
mysleep(40);
printf("Restartng data...\n");
}
sockClose(connfd);
}
}
sockQuit();
pthread_exit(NULL);
}
int main(void)
{
//cvNamedWindow("Sisplay", CV_WINDOW_AUTOSIZE);
sockInit();
pthread_mutex_init(&mutex,NULL);
VideoCapture cap;
Mat hereframe1;
cap.open(0);
cap.set( CV_CAP_PROP_FRAME_WIDTH, 160 );
cap.set( CV_CAP_PROP_FRAME_HEIGHT, 120 );
if( !cap.isOpened()) printf("Fukced up\n");
int rc;
long t;
rc = pthread_create(&thread, NULL, myfunc, (void *)t);
if (rc)
{
printf("ERROR; return code from pthread_create() is %d\n", rc);
exit(-1);
}
for(;;)
{
cap >> hereframe1;
// printf("Video size: %dX%d\n", hereframe1.rows, hereframe1.cols);
pthread_mutex_lock(&mutex);
hereframe1.copyTo(frame); /* hangs here*/
pthread_mutex_unlock(&mutex);
// cvtColor(frame, gray, CV_BGR2GRAY);
Scalar tempVal = mean(hereframe1);
// printf("Mean = %f\n", tempVal.val[0]);
mysleep(30);
//if(waitKey(30)=='q') break;
// std::swap(prevgray, gray);
}
char *b;
pthread_join(thread,(void**)&b);
return 0;
}
Client code
receiver.cpp
#define _GLIBCXX_USE_CXX11_ABI 0
#include "../mynet.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <opencv/cv.h>
#include <opencv/highgui.h>
using namespace cv;
int main(int argc, char *argv[])
{
int sockfd = 0,n = 0;
unsigned char recvBuff[120*160*3];
struct sockaddr_in serv_addr;
sockInit();
memset(recvBuff, '0',sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0))< 0)
{
printf("\n Error : Could not create socket \n");
return 1;
}
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(5000);
serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
if(connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr))<0)
{
printf("\n Error : Connect Failed \n");
return 1;
}
printf("Connected to server...\n");
Mat frame(120, 160, CV_8UC3);
int csz = 0;
cvNamedWindow("Display", CV_WINDOW_AUTOSIZE);
printf("OK here 0\n");
for(;;)
{
csz = 0;
while((n = recv(sockfd, (char*)recvBuff, sizeof(recvBuff), 0)) > 0)
{
printf("OK here 2\n");
printf("Read %d bytes...\n", n);
csz += n;
if(csz<=120*160*3)
{
memcpy(frame.data+(csz-n), recvBuff, n);
}
if(csz>= 120*160*3) break;
}
printf("OK here 3\n");
printf("Got data of size %d bytes...\n", csz);
imshow("Display", frame);
if(csz < 120*160*3)
{
printf("\n Read Error \n");
}
if(waitKey(30)=='q') break;
// std::swap(prevgray, gray);
}
sockClose(sockfd);
sockQuit();
return 0;
}
