From 0b3e9d5dc61bb705d93db1e87d78d8d5131905c6 Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefasab@gmail.com>
Date: Mon, 31 Oct 2011 11:32:11 +0100
Subject: [PATCH] vf_overlay: adopts FAST_DIV255 macro for calculating
destination alpha
Ease readability, improve exactness.
---
libavfilter/vf_overlay.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libavfilter/vf_overlay.c b/libavfilter/vf_overlay.c
index 06967c2db5b..6fa10aec8e5 100644
--- a/libavfilter/vf_overlay.c
+++ b/libavfilter/vf_overlay.c
@@ -452,7 +452,8 @@ static void blend_slice(AVFilterContext *ctx,
alpha = (alpha_v + alpha_h) >> 1;
} else
alpha = a[0];
- *d = (*d * (0xff - alpha) + *s++ * alpha + 128) >> 8;
+ *d = FAST_DIV255(*d * (255 - alpha) + *s * alpha);
+ s++;
d++;
a += 1 << hsub;
}
--
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