in StreamingASR/StreamingASR/app/src/main/cpp/librosa/librosa.h [145:154]
static Matrixf melspectrogram(Vectorf &x, int sr, int n_fft, int n_hop,
const std::string &win, bool center,
const std::string &mode, float power,
int n_mels, int fmin, int fmax){
Matrixcf X = stft(x, n_fft, n_hop, win, center, mode);
Matrixf mel_basis = melfilter(sr, n_fft, n_mels, fmin, fmax);
Matrixf sp = spectrogram(X, power);
Matrixf mel = mel_basis*sp.transpose();
return mel;
}