Error_t
RBJFilterSetCutoffD(RBJFilterD* filter, double cutoff)
{
filter->omega = HZ_TO_RAD(cutoff) / filter->sampleRate;
RBJFilterUpdateD(filter);
return NOERR;
}
/* RBJFilterSetCutoff **************************************************/
Error_t
RBJFilterSetCutoff(RBJFilter* filter, float cutoff)
{
filter->omega = HZ_TO_RAD(cutoff) / filter->sampleRate;
RBJFilterUpdate(filter);
return NOERR;
}
RBJFilterD*
RBJFilterInitD(Filter_t type, double cutoff, double sampleRate)
{
// Create the filter
RBJFilterD* filter = (RBJFilterD*)malloc(sizeof(RBJFilterD));
if (filter)
{
// Initialization
filter->type = type;
filter->omega = HZ_TO_RAD(cutoff) / sampleRate;
filter->Q = 1;
filter->A = 1;
filter->dbGain = 0;
filter->sampleRate = sampleRate;
// Initialize biquad
double b[3] = {0, 0, 0};
double a[2] = {0, 0};
filter->biquad = BiquadFilterInitD(b, a);
// Calculate coefficients
RBJFilterUpdateD(filter);
}
return filter;
}
/* RBJFilterInit **********************************************************/
RBJFilter*
RBJFilterInit(Filter_t type, float cutoff, float sampleRate)
{
// Create the filter
RBJFilter* filter = (RBJFilter*)malloc(sizeof(RBJFilter));
if (filter)
{
// Initialization
filter->type = type;
filter->omega = HZ_TO_RAD(cutoff) / sampleRate; //hzToRadians(cutoff, sampleRate);
filter->Q = 1;
filter->A = 1;
filter->dbGain = 0;
filter->sampleRate = sampleRate;
// Initialize biquad
float b[3] = {0, 0, 0};
float a[2] = {0, 0};
filter->biquad = BiquadFilterInit(b,a);
// Calculate coefficients
RBJFilterUpdate(filter);
}
return filter;
}
Error_t
RBJFilterSetParamsD(RBJFilterD* filter,
Filter_t type,
double cutoff,
double Q)
{
filter->type = type;
filter->omega = HZ_TO_RAD(cutoff) / filter->sampleRate;
filter->Q = Q;
RBJFilterUpdateD(filter);
return NOERR;
}
/* RBJFilterSetParams **************************************************/
Error_t
RBJFilterSetParams(RBJFilter* filter,
Filter_t type,
float cutoff,
float Q)
{
filter->type = type;
filter->omega = HZ_TO_RAD(cutoff) / filter->sampleRate;
filter->Q = Q;
RBJFilterUpdate(filter);
return NOERR;
}
void ctss_calculate_biquad_coeff(CTSS_DSPNode *node,
CTSS_BiquadType type,
float freq,
float dbGain,
float bandwidth) {
CTSS_BiquadState *state = node->state;
float a0, a1, a2, b0, b1, b2;
float A = powf(10.0f, dbGain / 40.0f);
float omega = HZ_TO_RAD(freq);
float sn = sinf(omega);
float cs = cosf(omega);
float alpha = sn * sinh(CT_LN2 / 2.0f * bandwidth * omega / sn);
float beta = sqrtf(A + A);
switch (type) {
case LPF:
default:
b0 = (1.0f - cs) / 2.0f;
b1 = 1.0f - cs;
b2 = (1.0f - cs) / 2.0f;
a0 = 1.0f + alpha;
a1 = -2.0f * cs;
a2 = 1.0f - alpha;
break;
case HPF:
b0 = (1.0f + cs) / 2.0f;
b1 = -(1.0f + cs);
b2 = (1.0f + cs) / 2.0f;
a0 = 1.0f + alpha;
a1 = -2.0f * cs;
a2 = 1.0f - alpha;
break;
case BPF:
b0 = alpha;
b1 = 0;
b2 = -alpha;
a0 = 1.0f + alpha;
a1 = -2.0f * cs;
a2 = 1.0f - alpha;
break;
case NOTCH:
b0 = 1.0f;
b1 = -2.0f * cs;
b2 = 1.0f;
a0 = 1.0f + alpha;
a1 = -2.0f * cs;
a2 = 1.0f - alpha;
break;
case PEQ:
b0 = 1.0f + (alpha * A);
b1 = -2.0f * cs;
b2 = 1.0f - (alpha * A);
a0 = 1.0f + (alpha / A);
a1 = -2.0f * cs;
a2 = 1.0f - (alpha / A);
break;
case LSH:
b0 = A * ((A + 1.0f) - (A - 1.0f) * cs + beta * sn);
b1 = 2.0f * A * ((A - 1.0f) - (A + 1.0f) * cs);
b2 = A * ((A + 1.0f) - (A - 1.0f) * cs - beta * sn);
a0 = (A + 1.0f) + (A - 1.0f) * cs + beta * sn;
a1 = -2.0f * ((A - 1.0f) + (A + 1.0f) * cs);
a2 = (A + 1.0f) + (A - 1.0f) * cs - beta * sn;
break;
case HSH:
b0 = A * ((A + 1.0f) + (A - 1.0f) * cs + beta * sn);
b1 = -2.0f * A * ((A - 1.0f) + (A + 1.0f) * cs);
b2 = A * ((A + 1.0f) + (A - 1.0f) * cs - beta * sn);
a0 = (A + 1.0f) - (A - 1.0f) * cs + beta * sn;
a1 = 2.0f * ((A - 1.0f) - (A + 1.0f) * cs);
a2 = (A + 1.0f) - (A - 1.0f) * cs - beta * sn;
break;
}
a0 = 1.0f / a0;
state->f[0] = b0 * a0;
state->f[1] = b1 * a0;
state->f[2] = b2 * a0;
state->f[3] = a1 * a0;
state->f[4] = a2 * a0;
state->f[5] = state->f[6] = state->f[7] = state->f[8] = 0.0f;
}
