title: Calling Gstreamer inside openCV
body: <p>I need to call Gstremaer inside an openCV code (opening a video camera essentially).
  As I looked through the source code, <code>modules/highgui/src/cap_gstreamer.cpp</code> seems to be the file I'm looking for.</p>
  
  <p>I compiled OpenCV with Gstreamer flag.</p>
  
  <pre><code> GStreamer:
  --       base:                      YES (ver 1.2.3)
  --       video:                     YES (ver 1.2.3)
  --       app:                       YES (ver 1.2.3)
  --       riff:                      YES (ver 1.2.3)
  --       pbutils:                   YES (ver 1.2.3)
  </code></pre>
  
  <p>but I'm not able to call a Gstreamer-related functions (e.g. <code>cvCreateCapture_GStreamer</code> which is defined inside <code>cap_gstreamer.cpp</code>)
  <code>cap_gstreamer.cpp</code> was built successfully as the opencv install log suggested:</p>
  
  <pre><code>[ 17%] Building CXX object modules/highgui/CMakeFiles/opencv_highgui.dir/src/cap_gstreamer.cpp.o
  </code></pre>
  
  <p><code>cvCreateCapture_GStreamer</code> is also present inside <code>/usr/local/lib/libopencv_highgui.so.3.0.0</code> after building openCV
  (found that using <code>grep</code>)</p>
  
  <p>I use <code>#include &lt;opencv/highgui.h&gt;</code> but calling <code>cvCreateCapture_GStreamer</code>fails(<code>-lopencv_highgui</code> flag is set inside the Makefile):</p>
  
  <pre><code>error: ‘cvCapture_GStreamer’ was not declared in this scope
  </code></pre>
  
  <p>Any suggestions would be helpful and greatly appreciated.</p>
  
  <p>Thanks!</p>