void vpx_img_flip ( vpx_image_t * img ) {
 img -> planes [ VPX_PLANE_Y ] += ( signed ) ( img -> d_h - 1 ) * img -> stride [ VPX_PLANE_Y ] ;
 img -> stride [ VPX_PLANE_Y ] = - img -> stride [ VPX_PLANE_Y ] ;
 img -> planes [ VPX_PLANE_U ] += ( signed ) ( ( img -> d_h >> img -> y_chroma_shift ) - 1 ) * img -> stride [ VPX_PLANE_U ] ;
 img -> stride [ VPX_PLANE_U ] = - img -> stride [ VPX_PLANE_U ] ;
 img -> planes [ VPX_PLANE_V ] += ( signed ) ( ( img -> d_h >> img -> y_chroma_shift ) - 1 ) * img -> stride [ VPX_PLANE_V ] ;
 img -> stride [ VPX_PLANE_V ] = - img -> stride [ VPX_PLANE_V ] ;
 img -> planes [ VPX_PLANE_ALPHA ] += ( signed ) ( img -> d_h - 1 ) * img -> stride [ VPX_PLANE_ALPHA ] ;
 img -> stride [ VPX_PLANE_ALPHA ] = - img -> stride [ VPX_PLANE_ALPHA ] ;
 }
void vpx_img_flip ( vpx_image_t * img ) {
 img -> planes [ VPX_PLANE_Y ] += ( signed ) ( img -> d_h - 1 ) * img -> stride [ VPX_PLANE_Y ] ;
 img -> stride [ VPX_PLANE_Y ] = - img -> stride [ VPX_PLANE_Y ] ;
 img -> planes [ VPX_PLANE_U ] += ( signed ) ( ( img -> d_h >> img -> y_chroma_shift ) - 1 ) * img -> stride [ VPX_PLANE_U ] ;
 img -> stride [ VPX_PLANE_U ] = - img -> stride [ VPX_PLANE_U ] ;
 img -> planes [ VPX_PLANE_V ] += ( signed ) ( ( img -> d_h >> img -> y_chroma_shift ) - 1 ) * img -> stride [ VPX_PLANE_V ] ;
 img -> stride [ VPX_PLANE_V ] = - img -> stride [ VPX_PLANE_V ] ;
 img -> planes [ VPX_PLANE_ALPHA ] += ( signed ) ( img -> d_h - 1 ) * img -> stride [ VPX_PLANE_ALPHA ] ;
 img -> stride [ VPX_PLANE_ALPHA ] = - img -> stride [ VPX_PLANE_ALPHA ] ;
 }