title: undefind reference to gst_element_register Qtcreator
body: <p>I'm trying to build a program in which I use gstreamer and opencv to manipulate images. This is my main file:</p>
  
  <pre><code>#include "GstSource.hpp"
  #include &lt;opencv2/highgui/highgui.hpp&gt;
  #include &lt;opencv2/highgui/highgui_c.h&gt;  
  #include &lt;iostream&gt;
  
  static const int Key_Escape  =  27;
  
  int main(int argc, char *argv[])
  {
  cv::namedWindow("Gstreamer");
  cvMoveWindow("Gstreamer",100,100);
  
  GstreamerPlayer player;
  if (! player.open("videotestsrc") )
      std::cerr &lt;&lt; "Unable to open pipeline" &lt;&lt; std::endl;
  
  if ( !player.setWidth(640) || !player.setHeight(480) ) {
      std::cerr &lt;&lt; "Unable to change resolution" &lt;&lt; std::endl;
      return 1;
  }
  
  
  bool fps_readed = false;
  while (true) {
      if (!player.grabFrame()) {
          std::cerr &lt;&lt; "Failed to grab frame" &lt;&lt; std::endl;
          break;
      }
      GstreamerImage * frame = player.getImage();
      if (!frame) {
          std::cerr &lt;&lt; "Failed to retrieve frame" &lt;&lt; std::endl;
          break;
      }
  
      if (!fps_readed) {
          std::cout &lt;&lt; "Video playing at " &lt;&lt; player.getFps() &lt;&lt; " fps" &lt;    std::endl;
          fps_readed = true;
      }
  
      cv::Mat canvas = cv::Mat(frame-&gt;height, frame-&gt;width, CV_8UC3, frame-&gt;data);
      if ( canvas.empty() )
          break;
      cv::imshow("Gstreamer", canvas);
  
      int key = cv::waitKey(10);
      if (key == Key_Escape)
          break;
  }
  }
  </code></pre>
  
  <p>and this is the .pro file:</p>
  
  <pre><code>QT       += core
  
  QT       -= gui
  
  TARGET = provaQT
  CONFIG   += console
  CONFIG   -= app_bundle
  
  TEMPLATE = app
  
  INCLUDEPATH += /usr/include/gstreamer-1.0 \
             /usr/local/include \
             /usr/include/glib-2.0 \
             /usr/lib/arm-linux-gnueabihf/glib-2.0/include \
             /usr/lib/arm-linux-gnueabihf
  
  LIBS += -L"/usr/lib/arm-linux-gnueabihf" -lglib-2.0 -lgobject-2.0 \
      -L"/usr/local/lib" -lopencv_core -lopencv_highgui -lopencv_imgcodecs    -lopencv_imgproc -lopencv_videoio \
      -L"/usr/lib/arm-linux-gnueabihf/gstreamer-1.0" -lgnl -lgst1394 -lgstaasink -lgstaccurip -lgstcoreelements \
      -L"/home/odroid/Desktop/Gstreamer-Test/bin/linux/gst-plugins" -lgst-overlay
  
  
  SOURCES += \
  ../Gstreamer-Test/src/gstinit.cpp \
  ../Gstreamer-Test/src/gstplugin.cpp \
  ../Gstreamer-Test/src/gstplugin_impl.cpp \
  ../Gstreamer-Test/src/GstSource.cpp \
  ../Gstreamer-Test/src/main.cpp \
  ../Gstreamer-Test/src/videotestoverlay.cpp
  
  HEADERS += \
  ../Gstreamer-Test/src/gstplugin.hpp \
  ../Gstreamer-Test/src/gstplugin_impl.hpp \
  ../Gstreamer-Test/src/GstSource.hpp \
  ../Gstreamer-Test/src/videotestoverlay.hpp  
  </code></pre>
  
  <p>and I get 147 error of this type: undefined reference to..... because many function used are declared but not defined. Where are their definition? How I can include their definition? </p>