From febcbd65fa3d00cfdfbfabd1c2a8fb8e659e1ca1 Mon Sep 17 00:00:00 2001
From: Robert Swain <robert.swain@gmail.com>
Date: Thu, 11 Sep 2008 01:22:34 +0000
Subject: [PATCH] Correct pulse amplitude application - a negative or 0
coefficient implies the pulse is subtracted, else it is added. Also avoid a
divide by 0.
Based on a patch by Alex Converse (alex converse gmail com)
Fixes part of issue632
Originally committed as revision 15294 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/aac.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/libavcodec/aac.c b/libavcodec/aac.c
index c59a663bec8..cc069ed7c66 100644
--- a/libavcodec/aac.c
+++ b/libavcodec/aac.c
@@ -753,7 +753,9 @@ static int decode_spectrum_and_dequant(AACContext * ac, float coef[1024], GetBit
if (pulse_present) {
for(i = 0; i < pulse->num_pulse; i++){
float co = coef_base[ pulse->pos[i] ];
- float ico = co / sqrtf(sqrtf(fabsf(co))) + pulse->amp[i];
+ float ico = -pulse->amp[i];
+ if (co)
+ ico = co / sqrtf(sqrtf(fabsf(co))) + (co > 0 ? -ico : ico);
coef_base[ pulse->pos[i] ] = cbrtf(fabsf(ico)) * ico;
}
}
--
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