title: GETSNAPSHOT in MATLAB is too slow
body: <p>I have a code which acquires images from an analog camera using a USB video grabber. The HUGE problem for me is that whenever I use GETSNAPSHOT to get an image, the process takes a few seconds to perform, while the frame rate of the device is actually 30 frames per second. The funny thing is that the <code>preview(vidObj)</code> works perfectly fine. I understand that there's been a lot of discussion over why GETSNAPHOT is so slow, and there's one proposed solution that is very popular using TRIGGERCONFIG, but for some reason, that doesn't do anything to boost the image acquisition rate for me. I'll explain both cases below:</p>
  
  <ol>
  <li><p>Directly using GETSNAPSHOT</p>
  
  <pre><code>obj = videoinput('winvideo', 2);
     while someconditionhere
     img= getsnapshot(cam); % extract frame i from the video
     imshow(img);
     %do stuff
  end
  </code></pre></li>
  <li><p>With TRIGGERCONFIG</p>
  
  <pre><code>obj = videoinput('winvideo', 2);
  triggerconfig(obj,'manual');
  start(obj);
  while someconditionhere
      img= getsnapshot(cam); % extract frame i from the video
      imshow(img);
      %do stuff
  end
  </code></pre></li>
  </ol>
  
  <p>I have tried to keep the preview window running in the background (a crude solution I found online) but then my while loop doesn't execute. Also, if in the first code, I add <code>start(obj)</code>, then it gives me an error: "A timeout occurred during GETSNAPSHOT."</p>
  
  <p>I'm running out of ideas and I have this due in a few hours. Any help would be greatly appreciated!</p>