message: videoio(macosx): fix array access exception in AVFoundation
diff: @@ -694,7 +694,15 @@ CvCaptureFile::CvCaptureFile(const char* filename) {
  return;
  }
  - mAssetTrack = [[mAsset tracksWithMediaType: AVMediaTypeVideo][0] retain];
  + NSArray *tracks = [mAsset tracksWithMediaType:AVMediaTypeVideo];
  + if ([tracks count] == 0) {
  + fprintf(stderr, "OpenCV: Couldn't read video stream from file \"%s\"\n", filename);
  + [localpool drain];
  + started = 0;
  + return;
  + }
  +
  + mAssetTrack = [tracks[0] retain];
  if ( ! setupReadingAt(kCMTimeZero) ) {
  fprintf(stderr, "OpenCV: Couldn't read movie file \"%s\"\n", filename);
  