title: problem on displaying live video in qt c++ application
body: <p>I want to show a live stream of the camera connected to raspberry in qt application (OS Linux). After googling it, I found out I must display the video inside QLabel. When displaying an image there's no problem and everything works fine, but when I want to display the live stream inside QLabel, the live stream window opens separately (not inside QLabel). would you tell me how to solve this problem? here's my code :</p>
  
  <pre><code>void Dialog::on_Preview_clicked()
  {
      command = "raspistill";
      args&lt;&lt;"-o"&lt;&lt;"/home/pi/Pictures/Preview/"+Date1.currentDateTime().toString()+".jpg"&lt;&lt;"-t"&lt;&lt;QString::number(20000);
      Pic.start(command,args,QIODevice::ReadOnly);
      QPixmap pix("//home//pi//Pictures//Preview//test.jpg");
      ui-&gt;label_2-&gt;setPixmap(pix);
      ui-&gt;label_2-&gt;setScaledContents(true);
  }
  </code></pre>
  
  <p>This code opens video capturing screen and captures an image after 20 seconds. the only problem is that the capture screen (which could be used as a live stream). isn't being displayed inside the "Lable_2". Is there anyway to do this without using OpenCV library? If not, tell me how to do it using OpenCV.</p>
  
  <p>Thanks</p>