MFCC MelFilter_to_MFCC (MelFilter me, long numberOfCoefficients) {
try {
autoNUMmatrix<double> cosinesTable (NUMcosinesTable (my ny), 1, 1);
autoNUMvector<double> x (1, my ny);
autoNUMvector<double> y (1, my ny);
double fmax_mel = my y1 + (my ny - 1) * my dy;
numberOfCoefficients = numberOfCoefficients > my ny - 1 ? my ny - 1 : numberOfCoefficients;
Melder_assert (numberOfCoefficients > 0);
// 20130220 new interpretation of maximumNumberOfCoefficients necessary for inverse transform
autoMFCC thee = MFCC_create (my xmin, my xmax, my nx, my dx, my x1, my ny - 1, my ymin, my ymax);
for (long frame = 1; frame <= my nx; frame++) {
CC_Frame cf = (CC_Frame) & thy frame[frame];
for (long i = 1; i <= my ny; i++) {
x[i] = my z[i][frame];
}
NUMcosineTransform (x.peek(), y.peek(), my ny, cosinesTable.peek());
CC_Frame_init (cf, numberOfCoefficients);
for (long i = 1; i <= numberOfCoefficients; i++) {
cf -> c[i] = y[i + 1];
}
cf -> c0 = y[1];
}
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": no MFCC created.");
}
}
MFCC MelFilter_to_MFCC (MelFilter me, long numberOfCoefficients) {
try {
long nf = my ny;
double fmax_mel = my y1 + (nf - 1) * my dy;
Melder_assert (numberOfCoefficients > 0);
autoNUMmatrix<double> dct (NUMcosinesTable (1, numberOfCoefficients, nf), 1, 1);
autoMFCC thee = MFCC_create (my xmin, my xmax, my nx, my dx, my x1, numberOfCoefficients, my y1, fmax_mel);
for (long frame = 1; frame <= my nx; frame++) {
CC_Frame cf = (CC_Frame) & thy frame[frame];
CC_Frame_init (cf, numberOfCoefficients);
for (long i = 1; i <= numberOfCoefficients; i++) {
double p = 0;
for (long j = 1; j <= nf; j++) {
p += my z[j][frame] * dct[i][j];
}
cf -> c[i] = p;
}
// c0 equals the average of the filterbank outputs.
double p = 0;
for (long j = 1; j <= nf; j++) {
p += my z[j][frame];
}
cf -> c0 = p / nf;
}
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": no MFCC created.");
}
}
MFCC MelSpectrogram_to_MFCC (MelSpectrogram me, long numberOfCoefficients) {
try {
if (numberOfCoefficients <= 0) {
numberOfCoefficients = my ny - 1;
}
numberOfCoefficients = numberOfCoefficients > my ny - 1 ? my ny - 1 : numberOfCoefficients;
// 20130220 new interpretation of maximumNumberOfCoefficients necessary for inverse transform
autoMFCC thee = MFCC_create (my xmin, my xmax, my nx, my dx, my x1, my ny - 1, my ymin, my ymax);
BandFilterSpectrogram_into_CC (me, thee.peek(), numberOfCoefficients);
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, U": MFCC not created.");
}
}
