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.");
}
}
/* Precondition: 1. CC object has been created but individual frames not yet initialized
* 2. Domains and number of frames conform
* Steps:
* 1. transform power-spectra to dB-spectra
* 2. cosine transform of dB-spectrum
*/
void BandFilterSpectrogram_into_CC (BandFilterSpectrogram me, CC thee, long numberOfCoefficients) {
autoNUMmatrix<double> cosinesTable (NUMcosinesTable (my ny), 1, 1);
autoNUMvector<double> x (1, my ny);
autoNUMvector<double> y (1, my ny);
numberOfCoefficients = numberOfCoefficients > my ny - 1 ? my ny - 1 : numberOfCoefficients;
Melder_assert (numberOfCoefficients > 0);
// 20130220 new interpretation of maximumNumberOfCoefficients necessary for inverse transform
for (long frame = 1; frame <= my nx; frame++) {
CC_Frame ccframe = (CC_Frame) & thy frame[frame];
for (long i = 1; i <= my ny; i++) {
x[i] = my v_getValueAtSample (frame, i, 1); // z[i][frame];
}
NUMcosineTransform (x.peek(), y.peek(), my ny, cosinesTable.peek());
CC_Frame_init (ccframe, numberOfCoefficients);
for (long i = 1; i <= numberOfCoefficients; i++) {
ccframe -> c[i] = y[i + 1];
}
ccframe -> c0 = y[1];
}
}
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");
}
}