diff --git a/doc/filters.texi b/doc/filters.texi
index b7762101a6..68f54f19b0 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -4243,6 +4243,12 @@ Apply uncover up-left effect:
 blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
 @end example
 
+@item
+Split diagonally video and shows top and bottom layer on each side:
+@example
+blend=all_expr=if(gt(X,Y*(W/H)),A,B)
+@end example
+
 @item
 Display differences between the current and the previous frame:
 @example