title: Preview issues for 1080P video using DirectShow
body: <p>I am using DirectShow in my application to capture video from webcams. I have issues while using cameras to preview and capture 1080P videos. Eg: HD Pro Webcam C910 camera of Logitech. 
  1080P video preview was very jerky and no HD clarity was observed. I could see that the enumerated device name was "USB Video Device"</p>
  
  <p>Today we installed Logitech webcam software on these XP machines . In that application, we could see the 1080P video without any jerking. Also we recorded 1080P video in the Logitech application and saw them in high quality. </p>
  
  <p>But when I test my application, </p>
  
  <ol>
  <li><p>I can see that the enumerated device name has been changed to "Logitech Pro Webcam C910" instead of the "USB Video Device" as in the previous case.</p></li>
  <li><p>The CPU eaten up by my application is 20%, but the process "SYSTEM" eats up 60%+ and the overall CPU revolves around 100%</p>
  
  <ol>
  <li><p>Even though the video quality has been greatly improved, the jerks are still there, may be due to the 100% CPU.</p></li>
  <li><p>When I closed my application, the high CPU utlizaton by "System" process goes away.</p></li>
  </ol></li>
  </ol>
  
  <p>Regarding my application - It uses ICaptureGraphBuilder2::RenderStream to create Preview and Capture streams. </p>
  
  <p>In Capture Stream, I connect Camera filter to NULL renderer with sample grabber as the intermediate filter. </p>
  
  <p>In preview stream, I have </p>
  
  <pre><code>g_pBuild-&gt;RenderStream(&amp;PIN_CATEGORY_PREVIEW,&amp;MEDIATYPE_Video,cam,NULL,NULL); 
  </code></pre>
  
  <p>Preview is displayed on a windows as specified using IVideoWindow interface. I use the following</p>
  
  <pre><code>g_vidWin-&gt;put_Owner((OAHWND)(HWND)hWnd);
  g_vidWin-&gt;put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS);
  g_vidWin-&gt;put_MessageDrain((OAHWND)hWnd);
  </code></pre>
  
  <p>I tried setting Frame rate to different values ( AvgTimePerFrame = 500000 ( 20 fps ) and 666667(15 fps) etc. </p>
  
  <p>But all the trials, still give the same result. Clarity has become more, but some jerks still remain and CPU is almost 100% due to 60+ % utlilization by "System". When I close my video application, usage by "System" goes back to 1-2 %.</p>
  
  <p>Any help on this is most welcome.</p>
  
  <p>Thanks in advance,</p>