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Reverb wrapping bugfix #33

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Reverb wrapping bugfix #33

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1c0ba96
attempt 1 fix reverb - still crap
djtuBIG-MaliceX Jan 5, 2021
2ff90a9
found the culprit - DC filter multiplication causing wrapping
djtuBIG-MaliceX Jan 5, 2021
41003fe
use C++-compliant C headers.
djtuBIG-MaliceX Jan 6, 2021
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2 changes: 1 addition & 1 deletion src/synth/constants.h
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Original file line number Diff line number Diff line change
Expand Up @@ -160,5 +160,5 @@ enum
#endif

#ifdef _WIN32
#define snprintf _snprintf
//#define snprintf _snprintf
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@djtuBIG-MaliceX djtuBIG-MaliceX Jan 6, 2021 •
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I had to comment this out as it was failing to build under MSYS2 MinGW-w64. This seems like a dirty hack anyway that likely no longer applies with more recent versions of MinGW-w64 GCC compiler suite.

#endif
59 changes: 34 additions & 25 deletions src/synth/reverb.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,9 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.

#include "constants.h"
#include "reverb.h"
#include <math.h>
#include <string.h>
#include <cmath>
#include <cstring>
#include <climits>

void CReverb::Init()
{
Expand Down Expand Up @@ -48,7 +49,7 @@ void CReverb::Init()
b1 = 0;
}

void CReverb::SetPar(char param, float value)
void CReverb::SetPar(char param, double value)
{
switch (param)
{
Expand All @@ -64,20 +65,21 @@ void CReverb::SetPar(char param, float value)
}
}

void CReverb::CalcCoefLowPass(float frequencia)
void CReverb::CalcCoefLowPass(double frequencia)
{
float w = 2.0f * sr;
float fCut = 2.0f * PI * Key2Frequency(frequencia * MAXFREQFLT);
float Norm = 1.0f / (fCut + w);
double w = 2.0f * sr;
double fCut = 2.0f * PI * Key2Frequency(frequencia * MAXFREQFLT);
double Norm = 1.0f / (fCut + w);
b1 = lrintf((w - fCut) * Norm * 32768.f);
a0 = a1 = lrintf( fCut * Norm * 32768.f);
}

void CReverb::Process(int *b, int size)
{
int i = 0;
int ent = 0;
int aux = 0;
int i = 0;
long ent = 0;
long aux = 0;
long smp = 0;
int retorno = (int)(ti * 127.f);
if (REVDAant != da)
{
Expand All @@ -87,46 +89,53 @@ void CReverb::Process(int *b, int size)
for (i=0;i<size;i++)
{
ent = b[i];
b[i] = 0;
smp = 0;
// comb 1
b[i] += bcomb1[icomb1];
smp += bcomb1[icomb1];
bcomb1[icomb1] = ent + ((bcomb1[icomb1] * retorno)/128);
if (++icomb1>=TAMCOMB1) icomb1 = 0;
// comb 2
b[i] += bcomb2[icomb2];
smp += bcomb2[icomb2];
bcomb2[icomb2] = ent + ((bcomb2[icomb2] * retorno)/128);
if (++icomb2>=TAMCOMB2) icomb2 = 0;
// comb 3
b[i] += bcomb3[icomb3];
smp += bcomb3[icomb3];
bcomb3[icomb3] = ent + ((bcomb3[icomb3] * retorno)/128);
if (++icomb3>=TAMCOMB3) icomb3 = 0;
// comb 4
b[i] += bcomb4[icomb4];
smp += bcomb4[icomb4];
bcomb4[icomb4] = ent + ((bcomb4[icomb4] * retorno)/128);
if (++icomb4>=TAMCOMB4) icomb4 = 0;
// allpass 1
aux = ballp1[iallp1];
ballp1[iallp1] = ((aux * retorno)/128) + b[i];
b[i] = aux - ((ballp1[iallp1] * retorno)/128);
ballp1[iallp1] = ((aux * retorno)/128) + smp;
smp = aux - ((ballp1[iallp1] * retorno)/128);
if (++iallp1>=TAMALLP1) iallp1 = 0;
// allpass 2
aux = ballp2[iallp2];
ballp2[iallp2] = ((aux * retorno)/128) + b[i];
ballp2[iallp2] = ((aux * retorno)/128) + smp;
b[i] = aux - ((ballp2[iallp2] * retorno)/128);
if (++iallp2>=TAMALLP2) iallp2 = 0;
// DC filter
ou0 = b[i] - in1 + ((ou0*32674)/32768);
in1 = b[i];
b[i] = ou0>>2;
ou0 = smp - in1 + (((double)ou0*32674)/32768);
in1 = smp;
smp = ou0>>2;

b[i] = (smp > INT_MAX) ? INT_MAX :
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@djtuBIG-MaliceX djtuBIG-MaliceX Jan 6, 2021

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Thinking more work might be needed to prevent double-clipping.

(smp < INT_MIN) ? INT_MIN :
smp;
}
if (REVDAant < 1.f)
{
for (i=0;i<size;i++)
{
smp = b[i];
// low pass filter
ou0l = ((b[i] * a0)/32768) + ((in1l * a1)/32768) + ((ou0l * b1)/32768);
in1l = b[i];
b[i] = ou0l;
ou0l = ((smp * a0)/32768) + ((in1l * a1)/32768) + ((ou0l * b1)/32768);
in1l = smp;
b[i] = (ou0l > INT_MAX) ? INT_MAX :
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@djtuBIG-MaliceX djtuBIG-MaliceX Jan 6, 2021

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As above, this may contribute to double-clipping.

(ou0l < INT_MIN) ? INT_MIN :
ou0l;
}
}
state = ACTIVE;
Expand All @@ -139,7 +148,7 @@ char CReverb::GetState()
return state;
}

inline float CReverb::Key2Frequency(float valor)
inline double CReverb::Key2Frequency(double valor)
{
return C0 * powf(2.0f, valor / 12.0f);
}
58 changes: 29 additions & 29 deletions src/synth/reverb.h
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Expand Up @@ -27,42 +27,42 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
class CReverb
{
private:
float sr;
float ti; // time
float da; // damp
double sr;
double ti; // time
double da; // damp
// combs buffers
int bcomb1[TAMCOMB1];
int bcomb2[TAMCOMB2];
int bcomb3[TAMCOMB3];
int bcomb4[TAMCOMB4];
long bcomb1[TAMCOMB1];
long bcomb2[TAMCOMB2];
long bcomb3[TAMCOMB3];
long bcomb4[TAMCOMB4];
// allpasses buffers
int ballp1[TAMALLP1];
int ballp2[TAMALLP2];
long ballp1[TAMALLP1];
long ballp2[TAMALLP2];
// buffers iterators
int icomb1;
int icomb2;
int icomb3;
int icomb4;
int iallp1;
int iallp2;
long icomb1;
long icomb2;
long icomb3;
long icomb4;
long iallp1;
long iallp2;
// DC filter
int in1;
int ou0;
long in1;
long ou0;
// low-pass filter
int in1l;
int ou0l;
int a0;
int a1;
int b1;
float REVDAant;
long in1l;
long ou0l;
long a0;
long a1;
long b1;
double REVDAant;
// other
char state;
// calculates low-pass coefs
void CalcCoefLowPass(float frequencia);
void CalcCoefLowPass(double frequencia);
public:
void Init();
char GetState(void);
void Process(int *b, int size);
inline float Key2Frequency(float valor);
void SetPar(char param, float value);
void Init();
char GetState(void);
void Process(int *b, int size);
inline double Key2Frequency(double valor);
void SetPar(char param, double value);
};