From e5d771c84deaa70ce9fab5951eee831cbe5e82a9 Mon Sep 17 00:00:00 2001
From: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Date: Wed, 9 Dec 2015 18:02:22 -0500
Subject: [PATCH] avfilter/avf_showfreqs: avoid wasteful pow

pow is a ridiculous function for computing a simple Gaussian.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
---
 libavfilter/avf_showfreqs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavfilter/avf_showfreqs.c b/libavfilter/avf_showfreqs.c
index a3665ef4bb..3ed0155f01 100644
--- a/libavfilter/avf_showfreqs.c
+++ b/libavfilter/avf_showfreqs.c
@@ -227,8 +227,9 @@ static void generate_window_func(float *lut, int N, int win_func, float *overlap
         *overlap = 0.75;
         break;
     case WFUNC_GAUSS:
+#define SQR(x) ((x)*(x))
         for (n = 0; n < N; n++)
-            lut[n] = pow(M_E,-0.5*pow((n-(N-1)/2)/(0.4*(N-1)/2.f),2));
+            lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
         *overlap = 0.75;
         break;
     default: