Refactor Biquad in preparation of EBU R128 loudness normalization.

src/effects/Biquad.cpp

@@ -2,31 +2,30 @@
 
 #define square(a) ((a)*(a))
 
-void Biquad_Process (BiquadStruct* pBQ, int iNumSamples)
+Biquad::Biquad()
+{
+   pfIn = 0;
+   pfOut = 0;
+   fNumerCoeffs[B0] = 1;
+   fNumerCoeffs[B1] = 0;
+   fNumerCoeffs[B2] = 0;
+   fDenomCoeffs[A1] = 0;
+   fDenomCoeffs[A2] = 0;
+   Reset();
+}
+
+void Biquad::Reset()
+{
+   fPrevIn = 0;
+   fPrevPrevIn = 0;
+   fPrevOut = 0;
+   fPrevPrevOut = 0;
+}
+
+void Biquad::Process(int iNumSamples)
 {
-   float* pfIn = pBQ->pfIn;
-   float* pfOut = pBQ->pfOut;
-   float fPrevIn = pBQ->fPrevIn;
-   float fPrevPrevIn = pBQ->fPrevPrevIn;
-   float fPrevOut = pBQ->fPrevOut;
-   float fPrevPrevOut = pBQ->fPrevPrevOut;
    for (int i = 0; i < iNumSamples; i++)
-   {
-      float fIn = *pfIn++;
-      *pfOut = fIn * pBQ->fNumerCoeffs [0] +
-         fPrevIn * pBQ->fNumerCoeffs [1] +
-         fPrevPrevIn * pBQ->fNumerCoeffs [2] -
-         fPrevOut * pBQ->fDenomCoeffs [0] -
-         fPrevPrevOut * pBQ->fDenomCoeffs [1];
-      fPrevPrevIn = fPrevIn;
-      fPrevIn = fIn;
-      fPrevPrevOut = fPrevOut;
-      fPrevOut = *pfOut++;
-   }
-   pBQ->fPrevIn = fPrevIn;
-   pBQ->fPrevPrevIn = fPrevPrevIn;
-   pBQ->fPrevOut = fPrevOut;
-   pBQ->fPrevPrevOut = fPrevPrevOut;
+      *pfOut++ = ProcessOne(*pfIn++);
 }
 
 void ComplexDiv (float fNumerR, float fNumerI, float fDenomR, float fDenomI, float* pfQuotientR, float* pfQuotientI)

src/effects/Biquad.h

@@ -1,37 +1,44 @@
 #ifndef __BIQUAD_H__
 #define __BIQUAD_H__
 
-#if 0
-//initialisations not supported in MSVC 2013.
-//Gives error C2905
-// Do not make conditional on compiler.
-typedef struct {
-   float* pfIn {};
-   float* pfOut {};
-   float fNumerCoeffs [3] { 1.0f, 0.0f, 0.0f };	// B0 B1 B2
-   float fDenomCoeffs [2] { 0.0f, 0.0f };	// A1 A2
-   float fPrevIn {};
-   float fPrevPrevIn {};
-   float fPrevOut {};
-   float fPrevPrevOut {};
-} BiquadStruct;
-#else
-// WARNING: This structure may need initialisation.
-typedef struct {
+struct Biquad
+{
+   Biquad();
+   void Reset();
+   void Process(int iNumSamples);
+
+   enum
+   {
+      /// Numerator coefficient indices
+      B0=0, B1, B2,
+      /// Denominator coefficient indices
+      A1=0, A2
+   };
+
+   inline float ProcessOne(float fIn)
+   {
+      float fOut = fIn * fNumerCoeffs[B0] +
+            fPrevIn * fNumerCoeffs[B1] +
+            fPrevPrevIn * fNumerCoeffs[B2] -
+            fPrevOut * fDenomCoeffs[A1] -
+            fPrevPrevOut * fDenomCoeffs[A2];
+      fPrevPrevIn = fPrevIn;
+      fPrevIn = fIn;
+      fPrevPrevOut = fPrevOut;
+      fPrevOut = fOut;
+      return fOut;
+   }
+
    float* pfIn;
    float* pfOut;
-   float fNumerCoeffs [3];	// B0 B1 B2
-   float fDenomCoeffs [2];	// A1 A2
+   float fNumerCoeffs[3]; // B0 B1 B2
+   float fDenomCoeffs[2]; // A1 A2, A0 == 1.0
    float fPrevIn;
    float fPrevPrevIn;
    float fPrevOut;
    float fPrevPrevOut;
-} BiquadStruct;
-#endif
+};
 
-
-
-void Biquad_Process (BiquadStruct* pBQ, int iNumSamples);
 void ComplexDiv (float fNumerR, float fNumerI, float fDenomR, float fDenomI, float* pfQuotientR, float* pfQuotientI);
 bool BilinTransform (float fSX, float fSY, float* pfZX, float* pfZY);
 float Calc2D_DistSqr (float fX1, float fY1, float fX2, float fY2);

src/effects/ScienFilter.cpp

@@ -218,12 +218,7 @@ unsigned EffectScienFilter::GetAudioOutCount()
 bool EffectScienFilter::ProcessInitialize(sampleCount WXUNUSED(totalLen), ChannelNames WXUNUSED(chanMap))
 {
    for (int iPair = 0; iPair < (mOrder + 1) / 2; iPair++)
-   {
-      mpBiquad[iPair].fPrevIn = 0;
-      mpBiquad[iPair].fPrevPrevIn = 0;
-      mpBiquad[iPair].fPrevOut = 0;
-      mpBiquad[iPair].fPrevPrevOut = 0;
-   }
+      mpBiquad[iPair].Reset();
 
    return true;
 }
@@ -235,7 +230,7 @@ size_t EffectScienFilter::ProcessBlock(float **inBlock, float **outBlock, size_t
    {
       mpBiquad[iPair].pfIn = ibuf;
       mpBiquad[iPair].pfOut = outBlock[0];
-      Biquad_Process(&mpBiquad[iPair], blockLen);
+      mpBiquad[iPair].Process(blockLen);
       ibuf = outBlock[0];
    }
 

src/effects/ScienFilter.h

@@ -102,7 +102,7 @@ private:
    int mFilterSubtype;	// lowpass, highpass
    int mOrder;
    int mOrderIndex;
-   ArrayOf<BiquadStruct> mpBiquad;
+   ArrayOf<Biquad> mpBiquad;
 
    double mdBMax;
    double mdBMin;