[FFmpeg-devel] [PATCH] vf_blend: Use integers for divide mode

Timothy Gu timothygu99 at gmail.com
Sun Feb 14 04:21:43 CET 2016


2.5x faster for 8-bit mode without autovectorization in GCC, 2x
slower with it on x86. However, since the platforms we enable GCC
autovectorization on most probably has support for SSE2
optimization (added in the subsequent commit), this commit should
in general do good.
---
 libavfilter/vf_blend.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavfilter/vf_blend.c b/libavfilter/vf_blend.c
index 2b734b4..b9e5add 100644
--- a/libavfilter/vf_blend.c
+++ b/libavfilter/vf_blend.c
@@ -240,7 +240,7 @@ DEFINE_BLEND8(hardlight,  (B < 128) ? MULTIPLY(2, B, A) : SCREEN(2, B, A))
 DEFINE_BLEND8(hardmix,    (A < (255 - B)) ? 0: 255)
 DEFINE_BLEND8(darken,     FFMIN(A, B))
 DEFINE_BLEND8(lighten,    FFMAX(A, B))
-DEFINE_BLEND8(divide,     av_clip_uint8(((float)A / ((float)B) * 255)))
+DEFINE_BLEND8(divide,     av_clip_uint8(B == 0 ? 255 : 255 * A / B))
 DEFINE_BLEND8(dodge,      DODGE(A, B))
 DEFINE_BLEND8(burn,       BURN(A, B))
 DEFINE_BLEND8(softlight,  (A > 127) ? B + (255 - B) * (A - 127.5) / 127.5 * (0.5 - fabs(B - 127.5) / 255): B - B * ((127.5 - A) / 127.5) * (0.5 - fabs(B - 127.5)/255))
@@ -280,7 +280,7 @@ DEFINE_BLEND16(hardlight,  (B < 32768) ? MULTIPLY(2, B, A) : SCREEN(2, B, A))
 DEFINE_BLEND16(hardmix,    (A < (65535 - B)) ? 0: 65535)
 DEFINE_BLEND16(darken,     FFMIN(A, B))
 DEFINE_BLEND16(lighten,    FFMAX(A, B))
-DEFINE_BLEND16(divide,     av_clip_uint16(((float)A / ((float)B) * 65535)))
+DEFINE_BLEND16(divide,     av_clip_uint16(B == 0 ? 65535 : 65535 * A / B))
 DEFINE_BLEND16(dodge,      DODGE(A, B))
 DEFINE_BLEND16(burn,       BURN(A, B))
 DEFINE_BLEND16(softlight,  (A > 32767) ? B + (65535 - B) * (A - 32767.5) / 32767.5 * (0.5 - fabs(B - 32767.5) / 65535): B - B * ((32767.5 - A) / 32767.5) * (0.5 - fabs(B - 32767.5)/65535))
-- 
2.1.4



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