fixed possible video distortion problem when cap_avfoundation.mm is used to…

fixed possible video distortion problem when cap_avfoundation.mm is used to capture video (ticket #1980)

modules/highgui/src/cap_avfoundation.mm

@@ -720,7 +720,7 @@ fromConnection:(AVCaptureConnection *)connection{
 		image->height = height; 
 		image->nChannels = 4; 
 		image->depth = IPL_DEPTH_8U; 
-		image->widthStep = rowBytes; 
+		image->widthStep = (int)rowBytes; 
 		image->imageData = imagedata; 
 		image->imageSize = currSize; 
 
@@ -731,7 +731,7 @@ fromConnection:(AVCaptureConnection *)connection{
 		bgr_image->height = height; 
 		bgr_image->nChannels = 3; 
 		bgr_image->depth = IPL_DEPTH_8U; 
-		bgr_image->widthStep = rowBytes; 
+		bgr_image->widthStep = (int)rowBytes; 
 		bgr_image->imageData = bgr_imagedata; 
 		bgr_image->imageSize = currSize; 
 
@@ -949,7 +949,7 @@ IplImage* CvCaptureFile::retrieveFramePixelBuffer() {
 		image->height = height; 
 		image->nChannels = 4; 
 		image->depth = IPL_DEPTH_8U; 
-		image->widthStep = width*4; 
+		image->widthStep = rowBytes; 
 		image->imageData = imagedata; 
 		image->imageSize = currSize; 
 
@@ -962,7 +962,7 @@ IplImage* CvCaptureFile::retrieveFramePixelBuffer() {
 		bgr_image->height = height; 
 		bgr_image->nChannels = 3; 
 		bgr_image->depth = IPL_DEPTH_8U; 
-		bgr_image->widthStep = width*4; 
+		bgr_image->widthStep = rowBytes; 
 		bgr_image->imageData = bgr_imagedata; 
 		bgr_image->imageSize = currSize;