> Maybe not only use multithreading for speedup, also need some
> algorithms to improve it.
> What about the speedup compare data?
Additionally, a fast implementation of box filtering is used and
sub-sampling as recommended in https://arxiv.org/abs/1505.00996. Current
implementation outperforms
--git a/libavfilter/vf_guided.c b/libavfilter/vf_guided.c
new file mode 100644
index 00..2bb640f686
--- /dev/null
+++ b/libavfilter/vf_guided.c
@@ -0,0 +1,400 @@
+/*
+ * Copyright (c) 2021 Andrey Moskalenko
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can
