From bca70b87efc40595e2bb469d63c77618872bd97b Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Fri, 15 Jul 2016 10:57:21 -0400
Subject: [PATCH] Fixes opus_pcm_soft_clip() returning values slightly larger
than +/-1 with -ffast-math
---
src/opus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/opus.c b/src/opus.c
index b7b0ea06c..2b47cdac6 100644
--- a/src/opus.c
+++ b/src/opus.c
@@ -104,6 +104,10 @@ OPUS_EXPORT void opus_pcm_soft_clip(float *_x, int N, int C, float *declip_mem)
/* Compute a such that maxval + a*maxval^2 = 1 */
a=(maxval-1)/(maxval*maxval);
+ /* Slightly boost "a" by 2^-24. This is just enough to ensure -ffast-math
+ does not cause output values larger than +/-1, but small enough not
+ to matter even for 24-bit output. */
+ a += a*6e-8;
if (x[i*C]>0)
a = -a;
/* Apply soft clipping */
--
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