[FFmpeg-cvslog] lavfi/af_compensationdelay: replace pow(x, 0.5) by sqrt(x)

Ganesh Ajjanagadde git at videolan.org
Wed Jan 6 04:09:05 CET 2016


ffmpeg | branch: master | Ganesh Ajjanagadde <gajjanagadde at gmail.com> | Mon Jan  4 18:40:19 2016 -0800| [fc703f53cf3b0ca3806ecbf20d456f36b04249af] | committer: Ganesh Ajjanagadde

lavfi/af_compensationdelay: replace pow(x,0.5) by sqrt(x)

sqrt is faster, and is sometimes more accurate depending on the libm.

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=fc703f53cf3b0ca3806ecbf20d456f36b04249af
---

 libavfilter/af_compensationdelay.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavfilter/af_compensationdelay.c b/libavfilter/af_compensationdelay.c
index 33ee7e4..d5a3484 100644
--- a/libavfilter/af_compensationdelay.c
+++ b/libavfilter/af_compensationdelay.c
@@ -57,7 +57,7 @@ AVFILTER_DEFINE_CLASS(compensationdelay);
 // The maximum distance for options
 #define COMP_DELAY_MAX_DISTANCE            (100.0 * 100.0 + 100.0 * 1.0 + 1.0)
 // The actual speed of sound in normal conditions
-#define COMP_DELAY_SOUND_SPEED_KM_H(temp)  1.85325 * (643.95 * pow(((temp + 273.15) / 273.15), 0.5))
+#define COMP_DELAY_SOUND_SPEED_KM_H(temp)  1.85325 * (643.95 * sqrt(((temp + 273.15) / 273.15)))
 #define COMP_DELAY_SOUND_SPEED_CM_S(temp)  (COMP_DELAY_SOUND_SPEED_KM_H(temp) * (1000.0 * 100.0) /* cm/km */ / (60.0 * 60.0) /* s/h */)
 #define COMP_DELAY_SOUND_FRONT_DELAY(temp) (1.0 / COMP_DELAY_SOUND_SPEED_CM_S(temp))
 // The maximum delay may be reached by this filter



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