From 010a66487d9b92f21d5b41c2d5956d8b79b58324 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Mon, 30 Apr 2012 09:33:00 -0700
Subject: [PATCH] Use 2 chained one-pole filters for the wet path

---
 Alc/ALu.c                   |  5 ++---
 Alc/mixer.c                 | 12 ++++++------
 OpenAL32/Include/alSource.h |  4 ++--
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/Alc/ALu.c b/Alc/ALu.c
index 2777b0fe..d3965dfd 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -308,8 +308,7 @@ ALvoid CalcNonAttnSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
     ALSource->Params.Direct.iirFilter.coeff = lpCoeffCalc(DryGainHF, cw);
     for(i = 0;i < NumSends;i++)
     {
-        /* We use a one-pole filter, so we need to take the squared gain */
-        ALfloat a = lpCoeffCalc(WetGainHF[i]*WetGainHF[i], cw);
+        ALfloat a = lpCoeffCalc(WetGainHF[i], cw);
         ALSource->Params.Send[i].iirFilter.coeff = a;
     }
 }
@@ -762,7 +761,7 @@ ALvoid CalcSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
     ALSource->Params.Direct.iirFilter.coeff = lpCoeffCalc(DryGainHF, cw);
     for(i = 0;i < NumSends;i++)
     {
-        ALfloat a = lpCoeffCalc(WetGainHF[i]*WetGainHF[i], cw);
+        ALfloat a = lpCoeffCalc(WetGainHF[i], cw);
         ALSource->Params.Send[i].iirFilter.coeff = a;
     }
 }
diff --git a/Alc/mixer.c b/Alc/mixer.c
index e925a5e8..75ede3dc 100644
--- a/Alc/mixer.c
+++ b/Alc/mixer.c
@@ -350,16 +350,16 @@ static void MixSend_##sampler(ALsource *Source, ALuint sendidx,               \
                                                                               \
         if(OutPos == 0)                                                       \
         {                                                                     \
-            value = sampler(data + pos*NumChannels + i, NumChannels,frac);    \
+            value = sampler(data + pos*NumChannels + i, NumChannels, frac);   \
                                                                               \
-            value = lpFilter1PC(WetFilter, i, value);                         \
+            value = lpFilter2PC(WetFilter, i, value);                         \
             WetClickRemoval[0] -= value * WetSend;                            \
         }                                                                     \
         for(BufferIdx = 0;BufferIdx < BufferSize;BufferIdx++)                 \
         {                                                                     \
-            value = sampler(data + pos*NumChannels + i, NumChannels,frac);    \
+            value = sampler(data + pos*NumChannels + i, NumChannels, frac);   \
                                                                               \
-            value = lpFilter1P(WetFilter, i, value);                          \
+            value = lpFilter2P(WetFilter, i, value);                          \
             WetBuffer[OutPos] += value * WetSend;                             \
                                                                               \
             frac += increment;                                                \
@@ -369,9 +369,9 @@ static void MixSend_##sampler(ALsource *Source, ALuint sendidx,               \
         }                                                                     \
         if(OutPos == SamplesToDo)                                             \
         {                                                                     \
-            value = sampler(data + pos*NumChannels + i, NumChannels,frac);    \
+            value = sampler(data + pos*NumChannels + i, NumChannels, frac);   \
                                                                               \
-            value = lpFilter1PC(WetFilter, i, value);                         \
+            value = lpFilter2PC(WetFilter, i, value);                         \
             WetPendingClicks[0] += value * WetSend;                           \
         }                                                                     \
         OutPos -= BufferSize;                                                 \
diff --git a/OpenAL32/Include/alSource.h b/OpenAL32/Include/alSource.h
index 88ced697..f76f618d 100644
--- a/OpenAL32/Include/alSource.h
+++ b/OpenAL32/Include/alSource.h
@@ -63,9 +63,9 @@ typedef struct SendParams {
      * output buffer. */
     ALfloat Gain;
 
-    /* A low-pass filter, using a one-pole filter. */
+    /* A low-pass filter, using 2 chained one-pole filters. */
     FILTER iirFilter;
-    ALfloat history[MAXCHANNELS];
+    ALfloat history[MAXCHANNELS*2];
 } SendParams;
 
 
-- 
2.11.4.GIT