I am trying to compile a very simple code with g++ (MacPorts gcc8 8.3.0_0) 8.3.0. I installed opencv4.1.0_2 with homebrew and it works perfectly for python. I need to switch to c++ at this point to use more transparent api functions. My code is:
#include <thread>
#include <opencv2/opencv.hpp>
#include <opencv2/core.hpp>
#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include "opencv2/imgcodecs/imgcodecs.hpp"
#include <iostream>
#include <stdio.h>
using namespace std;
using namespace cv;
const string ip = "192.168.122.1";
const string url1 = "http://"+ip+":8081/?action=stream";
const string url2 = "http://"+ip+":8082/?action=stream";
const string url3 = "http://"+ip+":8083/?action=stream";
const string url4 = "http://"+ip+":8084/?action=stream";
const string url5 = "http://"+ip+":8080/?action=stream";
const string url6 = "http://"+ip+":8085/?action=stream";
const string url7 = "http://"+ip+":8086/?action=stream";
void VideoGet(string url) {
UMat frame;
VideoCapture cap(url);
cap.open(url);
if (!cap.isOpened()) {
cerr << "Unable to open camera "+url+"\n";
return;
}
while (true) {
cap.read(frame);
if (frame.empty()) {
cerr << "Grabbed blank frame\n";
break;
}
}
}
int main() {
thread cam1(VideoGet,url1);
thread cam2(VideoGet,url2);
thread cam3(VideoGet,url3);
thread cam4(VideoGet,url4);
thread cam5(VideoGet,url5);
thread cam6(VideoGet,url6);
thread cam7(VideoGet,url7);
}
I compile with g++ ttc_multi_osx.cpp 'pkg-config opencv4 --cflags --libs' -o ttc_multi_osx.o
and the compiler throws
Undefined symbols for architecture x86_64:
"cv::VideoCapture::open(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)", referenced from:
VideoGet(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) in ccgUe88M.o
"cv::VideoCapture::VideoCapture(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)", referenced from:
VideoGet(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) in ccgUe88M.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
Any help would be very much appreciated.
