title: PJSIP project: the window handle created from pjsua allways NULL
body: <p>In a PJSIP project (Windows 32 Bit MFC/C++) we are working with SIP server to show the incoming video call. 
  Since using SDL / DirectShow (DirectX) layers, the SDL creates his own window to show incoming video (it works). My config_site.h looks like :</p>
  
  <pre><code>#define PJMEDIA_HAS_VIDEO           1
  #define PJMEDIA_HAS_FFMPEG          1
  #define PJMEDIA_VIDEO_DEV_HAS_SDL       1
  #define PJMEDIA_VIDEO_DEV_HAS_DSHOW     1
  </code></pre>
  
  <p>I would have the video showed in own windows rather than in SDL's window.
  So I try to get HWND of the SDL's window and to use it like a child window of own one:</p>
  
  <pre><code>pjsua_call_get_info(call_id, &amp;ci);
  for (unsigned i = 0; i &lt; ci.media_cnt; ++i) 
  {
    if ((ci.media[i].type == PJMEDIA_TYPE_VIDEO) &amp;&amp; 
       (ci.media[i].dir &amp; PJMEDIA_DIR_DECODING))
    {
      pjsua_vid_win_info wi;
      pjsua_vid_win_get_info(ci.media[i].stream.vid.win_in, &amp;wi);
      // Using handle like this or whatever:
      //HWND hwndOld = ::SetParent((HWND)&amp;wi.hwnd.info.win.hwnd, pWnd-&gt;m_hWnd);
      break;
    }
  }
  </code></pre>
  
  <p>The problem: <strong>wi.hwnd.info.win.hwnd</strong> is allways NULL !</p>
  
  <p>Maybe someone has the similar problem with SDL's windows? 
  The question is also, whether I obviosly need a SDL layer - maybe I shall just drop it using solely PJSIP? I mean:</p>
  
  <pre><code>#define PJMEDIA_HAS_VIDEO           1
  #define PJMEDIA_HAS_FFMPEG          1
  //#define PJMEDIA_VIDEO_DEV_HAS_SDL       1
  //#define PJMEDIA_VIDEO_DEV_HAS_DSHOW     1
  </code></pre>
  
  <p>I have tried this config but no video has been showed ...</p>