doc/filters: add one more blend example

Signed-off-by: Paul B Mahol <onemda@gmail.com>

diff --git a/doc/filters.texi b/doc/filters.texi
index abc3a0cae80d71115eea7dd4bcc1b23f2ffa04a7..710294860e1bf0122919dcffcaec4066ec166af3 100644 (file)
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -4994,6 +4994,12 @@ Apply transition from bottom layer to top layer in first 10 seconds:
 blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
 @end example
 
+@item
+Apply linear horizontal transition from top layer to bottom layer:
+@example
+blend=all_expr='A*(X/W)+B*(1-X/W)'
+@end example
+
 @item
 Apply 1x1 checkerboard effect:
 @example