title: openCV imdecode works slowly
body: <p>I'm working with MJPEG big sequences (e.g. 3000 JPEGs in sequence). I'm holding this JPEG sequence in vector of object containing JPEG data as <code>std::vector&lt;char&gt; vBufferPFDecode</code>. I want to show this data with openCV <code>hightGUI</code> methods (imshow), so I have to convert it to <code>cv::Mat</code> type with method:</p>
  
  <pre><code>cv::Mat pMat=cv::imdecode(cv::Mat(vBufferPFDecode), -1 );
  </code></pre>
  
  <p>It works, but to slowly - I can only get 8-10 frames per second. Do you know any alternative methods?</p>