static int Sound_into_LPC_Frame_burg (Sound me, LPC_Frame thee) {
int status = NUMburg (my z[1], my nx, thy a, thy nCoefficients, &thy gain);
thy gain *= my nx;
for (long i = 1; i <= thy nCoefficients; i++) {
thy a[i] = -thy a[i];
}
return status;
}
static void burg (double sample [], long nsamp_window, double cof [], int nPoles,
Formant_Frame frame, double nyquistFrequency, double safetyMargin)
{
double a0;
NUMburg (sample, nsamp_window, cof, nPoles, & a0);
/*
* Convert LP coefficients to polynomial.
*/
autoPolynomial polynomial = Polynomial_create (-1, 1, nPoles);
for (int i = 1; i <= nPoles; i ++)
polynomial -> coefficients [i] = - cof [nPoles - i + 1];
polynomial -> coefficients [nPoles + 1] = 1.0;
/*
* Find the roots of the polynomial.
*/
autoRoots roots = Polynomial_to_Roots (polynomial.peek());
Roots_fixIntoUnitCircle (roots.peek());
Melder_assert (frame -> nFormants == 0 && ! frame -> formant);
/*
* First pass: count the formants.
* The roots come in conjugate pairs, so we need only count those above the real axis.
*/
for (int i = roots -> min; i <= roots -> max; i ++) if (roots -> v [i]. im >= 0) {
double f = fabs (atan2 (roots -> v [i].im, roots -> v [i].re)) * nyquistFrequency / NUMpi;
if (f >= safetyMargin && f <= nyquistFrequency - safetyMargin)
frame -> nFormants ++;
}
/*
* Create space for formant data.
*/
if (frame -> nFormants > 0)
frame -> formant = NUMvector <structFormant_Formant> (1, frame -> nFormants);
/*
* Second pass: fill in the formants.
*/
int iformant = 0;
for (int i = roots -> min; i <= roots -> max; i ++) if (roots -> v [i]. im >= 0.0) {
double f = fabs (atan2 (roots -> v [i].im, roots -> v [i].re)) * nyquistFrequency / NUMpi;
if (f >= safetyMargin && f <= nyquistFrequency - safetyMargin) {
Formant_Formant formant = & frame -> formant [++ iformant];
formant -> frequency = f;
formant -> bandwidth = -
log (roots -> v [i].re * roots -> v [i].re + roots -> v [i].im * roots -> v [i].im) * nyquistFrequency / NUMpi;
}
}
Melder_assert (iformant == frame -> nFormants); // may fail if some frequency is NaN
}
autoSpectrum Spectrum_lpcSmoothing (Spectrum me, int numberOfPeaks, double preemphasisFrequency) {
try {
double gain, a [100];
long numberOfCoefficients = 2 * numberOfPeaks;
autoSound sound = Spectrum_to_Sound (me);
NUMpreemphasize_f (sound -> z [1], sound -> nx, sound -> dx, preemphasisFrequency);
NUMburg (sound -> z [1], sound -> nx, a, numberOfCoefficients, & gain);
for (long i = 1; i <= numberOfCoefficients; i ++) a [i] = - a [i];
autoSpectrum thee = Data_copy (me);
long nfft = 2 * (thy nx - 1);
long ndata = numberOfCoefficients < nfft ? numberOfCoefficients : nfft - 1;
double scale = 10 * (gain > 0 ? sqrt (gain) : 1) / numberOfCoefficients;
autoNUMvector <double> data (1, nfft);
data [1] = 1;
for (long i = 1; i <= ndata; i ++)
data [i + 1] = a [i];
NUMrealft (data.peek(), nfft, 1);
double *re = thy z [1];
double *im = thy z [2];
re [1] = scale / data [1];
im [1] = 0.0;
long halfnfft = nfft / 2;
for (long i = 2; i <= halfnfft; i ++) {
double real = data [i + i - 1], imag = data [i + i];
re [i] = scale / sqrt (real * real + imag * imag) / (1 + thy dx * (i - 1) / preemphasisFrequency);
im [i] = 0;
}
re [halfnfft + 1] = scale / data [2] / (1 + thy dx * halfnfft / preemphasisFrequency);
im [halfnfft + 1] = 0.0;
return thee;
} catch (MelderError) {
Melder_throw (me, U": not smoothed.");
}
}
