Try a different low-pass filter

Seems to be more correct, although it's not as powerful as the previous (which
may be a good thing)

1 files changed, 6 insertions, 4 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index ce669791..eefab9ee 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -211,8 +211,9 @@ static __inline ALfloat aluComputeDrySample(ALsource *source, ALfloat DryGainHF,
 {
     if(DryGainHF < 1.0f)
     {
-        sample *= DryGainHF;
-        sample += source->LastDrySample * (1.0f - DryGainHF);
+        ALfloat u = sample + source->LastDrySample;
+        ALfloat v = sample - source->LastDrySample;
+        sample = (u + (v*DryGainHF)) * 0.5;
     }
 
     source->LastDrySample = sample;
@@ -223,8 +224,9 @@ static __inline ALfloat aluComputeWetSample(ALsource *source, ALfloat WetGainHF,
 {
     if(WetGainHF < 1.0f)
     {
-        sample *= WetGainHF;
-        sample += source->LastWetSample * (1.0f - WetGainHF);
+        ALfloat u = sample + source->LastWetSample;
+        ALfloat v = sample - source->LastWetSample;
+        sample = (u + (v*WetGainHF)) * 0.5;
     }
 
     source->LastWetSample = sample;