VideoCapture OpenCV Error?

[Helaly96]

i installed opencv on Ubuntu and tested it outside of qt with a simple C++ script, and it worked just fine.

My compiler is GCC 5.3.1

now i want to use in QT widgets application.

pkg-config --modversion opencv
2.4.9.1

above is the version of the Opencv installed.

here is the .pro file

-------------------------------------------------

QT += core gui network



greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += \
        main.cpp

HEADERS +=

FORMS +=


INCLUDEPATH += /usr/local/include/opencv
LIBS += -L/usr/local/lib -lopencv_shape -lopencv_videoio -lopencv_highgui




# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

here is the main.cpp file

#include "mainwindow.h"
#include <QApplication>
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/video/video.hpp"


using namespace cv;
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    VideoCapture cap(0); // get first cam
        while( cap.isOpened() )
        {
            Mat frame;
            if ( ! cap.read(frame) ) // cam might need some warmup
                continue;

            // your processing goes here

            imshow("lalala",frame);
            if ( waitKey(10)==27 )
                break;
        }

    return a.exec();
}

i followed this link and reached this point

https://forum.qt.io/topic/92848/opencv-error-undefined-reference-to-cv-videocapture-videocapture

and reached this compiler error

anyone know the issue ?

[Helaly96]

This post is deleted!

[SGaist]

Hi and welcome to devnet,

You can use pkg-config with qmake. See if it helps with OpenCV.