Fix bugs in IIR and oversampling classes

jatinchowdhury18 · Sep 10, 2020 · 21701fb · 21701fb
1 parent b67a810
commit 21701fb
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Showing 2 changed files with 20 additions and 20 deletions.
diff --git a/src/shared/iir.hpp b/src/shared/iir.hpp
@@ -216,22 +216,22 @@ struct TBiquadFilter : IIRFilter<3, T> {
 			} break;
 
 			case PEAK: {
-				if (V >= 1.f) {
-					float norm = 1.f / (1.f + K / Q + K * K);
-					this->b[0] = (1.f + K / Q * V + K * K) * norm;
-					this->b[1] = 2.f * (K * K - 1.f) * norm;
-					this->b[2] = (1.f - K / Q * V + K * K) * norm;
-					this->a[1] = this->b[1];
-					this->a[2] = (1.f - K / Q + K * K) * norm;
-				}
-				else {
-					float norm = 1.f / (1.f + K / Q / V + K * K);
-					this->b[0] = (1.f + K / Q + K * K) * norm;
-					this->b[1] = 2.f * (K * K - 1.f) * norm;
-					this->b[2] = (1.f - K / Q + K * K) * norm;
-					this->a[1] = this->b[1];
-					this->a[2] = (1.f - K / Q / V + K * K) * norm;
-				}
+                float c = 1.0f / K;
+                float phi = c * c;
+                float Knum = c / Q;
+                float Kdenom = Knum;
+
+                if(V > 1.0f)
+                    Knum *= V;
+                else
+                    Kdenom /= V;
+
+                float norm = phi + Kdenom + 1.0;
+                this->b[0] = (phi + Knum + 1.0f) / norm;
+                this->b[1] = 2.0f * (1.0f - phi) / norm;
+                this->b[2] = (phi - Knum + 1.0f) / norm;
+                this->a[1] = 2.0f * (1.0f - phi) / norm;
+                this->a[2] = (phi - Kdenom + 1.0f) / norm;
 			} break;
 
 			case NOTCH: {

diff --git a/src/shared/oversampling.hpp b/src/shared/oversampling.hpp
@@ -29,12 +29,12 @@ class AAFilter
         return Qs;
     }
 
-    void reset(float sampleRate) {
+    void reset(float sampleRate, int osRatio) {
         float fc = 0.98f * (sampleRate / 2.0f);
         auto Qs = calculateButterQs(2*N);
 
         for(int i = 0; i < N; ++i)
-            filters[i].setParameters(BiquadFilter::Type::LOWPASS, fc / sampleRate, Qs[i], 1.0f);
+            filters[i].setParameters(BiquadFilter::Type::LOWPASS, fc / (osRatio * sampleRate), Qs[i], 1.0f);
     }
 
     inline float process(float x) noexcept {
@@ -58,8 +58,8 @@ class OversampledProcess
     OversampledProcess() = default;
 
     void reset(float baseSampleRate) {
-        aaFilter.reset(baseSampleRate);
-        aiFilter.reset(baseSampleRate);
+        aaFilter.reset(baseSampleRate, ratio);
+        aiFilter.reset(baseSampleRate, ratio);
     }
 
     using OSProcess = std::function<float(float)>;