/*
* Transforms a parameter to the real value
*/
REALTYPE FilterParams::getformantfreq(unsigned char freq)
{
REALTYPE result = getfreqx(freq / 127.0);
return result;
}
/*
* Get the x coordinate from frequency (used by the UI)
*/
REALTYPE FilterParams::getfreqpos(REALTYPE freq)
{
return (log(freq) - log(getfreqx(0.0))) / log(2.0) / getoctavesfreq();
}
/*
* Get the freq. response of the formant filter
*/
void FilterParams::formantfilterH(int nvowel, int nfreqs, REALTYPE *freqs)
{
REALTYPE c[3], d[3];
REALTYPE filter_freq, filter_q, filter_amp;
REALTYPE omega, sn, cs, alpha;
for(int i = 0; i < nfreqs; i++)
freqs[i] = 0.0;
//for each formant...
for(int nformant = 0; nformant < Pnumformants; nformant++) {
//compute formant parameters(frequency,amplitude,etc.)
filter_freq = getformantfreq(Pvowels[nvowel].formants[nformant].freq);
filter_q = getformantq(Pvowels[nvowel].formants[nformant].q) * getq();
if(Pstages > 0)
filter_q =
(filter_q > 1.0 ? POW(filter_q, 1.0 / (Pstages + 1)) : filter_q);
filter_amp = getformantamp(Pvowels[nvowel].formants[nformant].amp);
if(filter_freq <= (SAMPLE_RATE / 2 - 100.0)) {
omega = 2 * PI * filter_freq / SAMPLE_RATE;
sn = sin(omega);
cs = cos(omega);
alpha = sn / (2 * filter_q);
REALTYPE tmp = 1 + alpha;
c[0] = alpha / tmp *sqrt(filter_q + 1);
c[1] = 0;
c[2] = -alpha / tmp *sqrt(filter_q + 1);
d[1] = -2 * cs / tmp * (-1);
d[2] = (1 - alpha) / tmp * (-1);
}
else
continue;
for(int i = 0; i < nfreqs; i++) {
REALTYPE freq = getfreqx(i / (REALTYPE) nfreqs);
if(freq > SAMPLE_RATE / 2) {
for(int tmp = i; tmp < nfreqs; tmp++)
freqs[tmp] = 0.0;
break;
}
REALTYPE fr = freq / SAMPLE_RATE * PI * 2.0;
REALTYPE x = c[0], y = 0.0;
for(int n = 1; n < 3; n++) {
x += cos(n * fr) * c[n];
y -= sin(n * fr) * c[n];
}
REALTYPE h = x * x + y * y;
x = 1.0;
y = 0.0;
for(int n = 1; n < 3; n++) {
x -= cos(n * fr) * d[n];
y += sin(n * fr) * d[n];
}
h = h / (x * x + y * y);
freqs[i] += POW(h, (Pstages + 1.0) / 2.0) * filter_amp;
}
}
for(int i = 0; i < nfreqs; i++) {
if(freqs[i] > 0.000000001)
freqs[i] = rap2dB(freqs[i]) + getgain();
else
freqs[i] = -90.0;
}
}
/*
* Get the x coordinate from frequency (used by the UI)
*/
REALTYPE Resonance::getfreqpos(REALTYPE freq){
return((log(freq)-log(getfreqx(0.0)))/log(2.0)/getoctavesfreq());
};
