Spectrogram

Spectrogram class

`MelSpectrogram`([num, samplate, low_fre, ...])	Mel spectrogram class.
`BarkSpectrogram`([num, samplate, low_fre, ...])	Bark spectrogram class.
`ErbSpectrogram`([num, samplate, low_fre, ...])	Erb spectrogram class.

`mfcc`(X[, cc_num, rectify_type, mel_num, ...])	Mel-frequency cepstral coefficients (MFCCs)
`bfcc`(X[, cc_num, rectify_type, bark_num, ...])	Bark-frequency cepstral coefficients (BFCCs)
`gtcc`(X[, cc_num, rectify_type, erb_num, ...])	Gammatone cepstral coefficients (GTCCs)
`cqcc`(X[, cc_num, rectify_type, cqt_num, ...])	Constant-Q cepstral coefficients (CQCCs)

`chroma_linear`(X[, chroma_num, radix2_exp, ...])	Linear(STFT) chromagram
`chroma_octave`(X[, chroma_num, radix2_exp, ...])	Octave chromagram
`chroma_cqt`(X[, chroma_num, num, samplate, ...])	Constant-Q chromagram

`linear_spectrogram`(X[, num, radix2_exp, ...])	Short-time Fourier transform (Linear/STFT)
`mel_spectrogram`(X[, num, radix2_exp, ...])	Mel-scale spectrogram.
`bark_spectrogram`(X[, num, radix2_exp, ...])	Bark-scale spectrogram.
`erb_spectrogram`(X[, num, radix2_exp, ...])	Erb-scale spectrogram.
`cqt`(X[, num, samplate, low_fre, ...])	Constant-Q transform (CQT)
`vqt`(X[, num, samplate, low_fre, ...])	Variable-Q transform (VQT)