title: OpenCV VideoCapture not opens file ios
body: <p>I've saved a video to a file using:</p>
  
  <pre><code>NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
  documentsDirectory = [documentsDirectory stringByAppendingPathComponent:@"test9.avi"];
  
  NSLog(@"Open to: %@", documentsDirectory);
  
  std::string fileName([documentsDirectory cString], [documentsDirectory cStringLength]);
  videoWriter = new cv::VideoWriter(fileName, CV_FOURCC('H', 'F', 'Y', 'U'), 25, cvSize(288,352),1);
  </code></pre>
  
  <p>But I can't open this with VideoCapture:</p>
  
  <pre><code>NSLog(@"Load the video");
  videoCapture = new cv::VideoCapture();
  NSLog(@"Video loaded");
  if (videoCapture-&gt;open(fileName))
  {
      NSLog(@"Opened");
  }
  else {
      NSLog(@"Failed to open");
  }
  </code></pre>
  
  <p>There is no error from the VideoCapture itself just my log "Failed to open" ...
  Can I somehow get more detailed error log?</p>