MelFilter MFCC_to_MelFilter (MFCC me, long first, long last) {
try {
long nf = my maximumNumberOfCoefficients + 1;
autoNUMmatrix<double> cosinesTable (NUMcosinesTable (nf), 1, 1);
autoNUMvector<double> x (1, nf);
autoNUMvector<double> y (1, nf);
if (first >= last) {
first = 0; last = nf - 1;
}
if (first < 0 || last > nf - 1) {
Melder_throw ("MFCC_to_MelFilter: coefficients must be in interval [0,", my maximumNumberOfCoefficients, "].");
}
double df = (my fmax - my fmin) / (nf + 1);
autoMelFilter thee = MelFilter_create (my xmin, my xmax, my nx, my dx, my x1, my fmin, my fmax, nf, df, df);
for (long frame = 1; frame <= my nx; frame++) {
CC_Frame cf = (CC_Frame) & my frame[frame];
long iend = MIN (last, cf -> numberOfCoefficients);
x[1] = first == 0 ? cf -> c0 : 0;
for (long i = 1; i <= my maximumNumberOfCoefficients; i++) {
x[i + 1] = i < first || i > iend ? 0 : cf -> c[i];
}
NUMinverseCosineTransform (x.peek(), y.peek(), nf, cosinesTable.peek());
for (long i = 1; i <= nf; i++) {
thy z[i][frame] = y[i];
}
}
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": no MelFilter created.");
}
}
// Preconditions: Domains and number of frames conform
// 0 <= first <= last <= my ny-1
void CC_into_BandFilterSpectrogram (CC me, BandFilterSpectrogram thee, long first, long last, bool use_c0) {
long nf = my maximumNumberOfCoefficients + 1;
autoNUMmatrix<double> cosinesTable (NUMcosinesTable (nf), 1, 1);
autoNUMvector<double> x (1, nf);
autoNUMvector<double> y (1, nf);
for (long frame = 1; frame <= my nx; frame++) {
CC_Frame ccframe = (CC_Frame) & my frame[frame];
long iend = last < ccframe -> numberOfCoefficients ? last : ccframe -> numberOfCoefficients;
x[1] = use_c0 ? ccframe -> c0 : 0;
for (long i = 1; i <= my maximumNumberOfCoefficients; i++) {
x[i + 1] = i < first || i > iend ? 0 : ccframe -> c[i];
}
NUMinverseCosineTransform (x.peek(), y.peek(), nf, cosinesTable.peek());
for (long i = 1; i <= nf; i++) {
thy z[i][frame] = BandFilterSpectrogram_DBREF * pow (10, y[i] / BandFilterSpectrogram_DBFAC);
}
}
}
double testCosineTransform (long n) {
try {
autoNUMvector<double> x (1, n);
autoNUMvector<double> y (1, n);
autoNUMvector<double> x2 (1, n);
autoNUMmatrix<double> cosinesTable (NUMcosinesTable (n), 1, 1);
for (long i = 1 ; i <= n; i++) {
x[i] = NUMrandomUniform (0, 70);
}
NUMcosineTransform (x.peek(), y.peek(), n, cosinesTable.peek());
NUMinverseCosineTransform (y.peek(), x2.peek(), n, cosinesTable.peek());
double delta = 0;
for (long i =1 ; i <= n; i++) {
double dif = x[i] - x2[i];
delta += dif * dif;
}
delta = sqrt (delta);
return delta;
} catch (MelderError) {
Melder_throw ("Test cosine transform error");
}
}
