Fix the voice LPF implementation

2 files changed, 4 insertions, 4 deletions

diff --git a/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AXStructs.h b/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AXStructs.h
index cc24bd78b7..2ac9ddd2f0 100644
--- a/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AXStructs.h
+++ b/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AXStructs.h
@@ -231,8 +231,8 @@ struct PBLowPassFilter
 {
 	u16 enabled;
 	s16 yn1;
-	s16 a0;
-	s16 b0;
+	u16 a0;
+	u16 b0;
 };
 
 struct AXPB
diff --git a/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AX_Voice.h b/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AX_Voice.h
index fcc1bb7999..f41c4c47ff 100644
--- a/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AX_Voice.h
+++ b/Source/Core/Core/Src/HW/DSPHLE/UCodes/UCode_AX_Voice.h
@@ -342,10 +342,10 @@ void MixAdd(int* out, const s16* input, u32 count, u16* pvol, s16* dpop, bool ra
 
 // Execute a low pass filter on the samples using one history value. Returns
 // the new history value.
-s16 LowPassFilter(s16* samples, u32 count, s16 yn1, s16 a0, s16 b0)
+s16 LowPassFilter(s16* samples, u32 count, s16 yn1, u16 a0, u16 b0)
 {
 	for (u32 i = 0; i < count; ++i)
-		yn1 = samples[i] = (s32)a0 * samples[i] - (s32)b0 * yn1;
+		yn1 = samples[i] = (a0 * (s32)samples[i] + b0 * (s32)yn1) >> 15;
 	return yn1;
 }