From 2fbdc4faf1bc0740cf18b0267c017e2afafaa99e Mon Sep 17 00:00:00 2001
From: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Date: Mon, 4 Jan 2016 18:37:16 -0800
Subject: [PATCH] lavfi/avf_showspectrum: replace pow(x, 0.25) by sqrt(sqrt(x))

This is faster; precision assured as result is a float.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
---
 libavfilter/avf_showspectrum.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index 3611c96a5e..88bee3cb6e 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -590,7 +590,7 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFrame *insamples)
                 a = cbrt(a);
                 break;
             case FOURTHRT:
-                a = pow(a, 0.25);
+                a = sqrt(sqrt(a));
                 break;
             case FIFTHRT:
                 a = pow(a, 0.20);