public static void SetResonantLowpassCoefficients(
ResonantLowpassRec Filter,
double Cutoff,
double Bandwidth,
double Gain,
double SamplingRate)
{
if ((Cutoff == Filter.OldCutoff) && (Bandwidth == Filter.OldBandwidth) && (Gain == Filter.OldGain))
{
return;
}
Filter.OldCutoff = Cutoff;
Filter.OldBandwidth = Bandwidth;
Filter.OldGain = Gain;
if (Filter.NumLowpassSections != 0)
{
/* initialize first one */
ButterworthLowpassRec.ComputeButterworthLowpassCoefficients(
ref Filter.iir[0],
Cutoff,
SamplingRate);
/* copy to the others */
for (int i = 1; i < Filter.NumLowpassSections; i += 1)
{
Filter.iir[i].A0 = Filter.iir[0].A0;
Filter.iir[i].A1 = Filter.iir[0].A1;
Filter.iir[i].A2 = Filter.iir[0].A2;
Filter.iir[i].B1 = Filter.iir[0].B1;
Filter.iir[i].B2 = Filter.iir[0].B2;
}
}
if (Filter.NumBandpassSections != 0)
{
/* initialize first one */
ButterworthBandpassRec.ComputeButterworthBandpassCoefficients(
ref Filter.iir[Filter.NumLowpassSections + 0],
Cutoff,
Bandwidth,
SamplingRate);
/* copy to the others */
for (int i = 1; i < Filter.NumBandpassSections; i += 1)
{
Filter.iir[Filter.NumLowpassSections + i].A0 = Filter.iir[Filter.NumLowpassSections + 0].A0;
Filter.iir[Filter.NumLowpassSections + i].A1 = Filter.iir[Filter.NumLowpassSections + 0].A1;
Filter.iir[Filter.NumLowpassSections + i].A2 = Filter.iir[Filter.NumLowpassSections + 0].A2;
Filter.iir[Filter.NumLowpassSections + i].B1 = Filter.iir[Filter.NumLowpassSections + 0].B1;
Filter.iir[Filter.NumLowpassSections + i].B2 = Filter.iir[Filter.NumLowpassSections + 0].B2;
}
}
Filter.BandpassGain = (float)Gain;
}
public static void SetButterworthLowpassCoefficients(
ButterworthLowpassRec Filter,
double Cutoff,
double SamplingRate)
{
if (Cutoff == Filter.OldCutoff)
{
return;
}
Filter.OldCutoff = Cutoff;
ComputeButterworthLowpassCoefficients(
ref Filter.iir,
Cutoff,
SamplingRate);
}
/* apply filter to an array of values, adding result to output array */
public void Apply(
float[] XinVector,
int XInVectorOffset,
float[] YoutVector,
int YoutVectorOffset,
int VectorLength,
float OutputScaling,
SynthParamRec SynthParams)
{
ButterworthLowpassRec Filter = this;
IIR2DirectIMAcc(
ref Filter.iir,
XinVector,
XInVectorOffset,
YoutVector,
YoutVectorOffset,
VectorLength,
OutputScaling);
}
