title: Opencv CAP_PROP_FRAME_COUNT return negative larg number
body: <p>VideoCapture capture(captureFileName);
  I am using Opencv 3.3.1. 
  I am using the following cod.</p>
  
  <pre><code>    if (!capture.isOpened()) {
          throw "Error when reading file";
      }
  
      cout &lt;&lt; "capture.get(CAP_PROP_FRAME_COUNT)"
              &lt;&lt; capture.get(CAP_PROP_FRAME_COUNT) &lt;&lt; endl;
      cout &lt;&lt; "capture.get(CV_CAP_PROP_FPS)" &lt;&lt; capture.get(CV_CAP_PROP_FPS)
              &lt;&lt; endl;
  </code></pre>
  
  <p>When the video size is around 30MB, capture.get(CAP_PROP_FRAME_COUNT) return value around 16632. However, when the video size is around 150MB, capture.get(CAP_PROP_FRAME_COUNT) return value around -2.30584e+14. </p>
  
  <p>The rest of the code cannot run as well (after that line). Did anyone run large video with opencv before?</p>
  
  <hr>
  
  <p>update:</p>
  
  <p>I realized the problem is in the source video. I download the stream with vlc and it did not stop recording properly and a 1 minute video is more than 100mb(frames after 30mb are corrupted). VideoCapture works well on other video. </p>