CEPSTRUM

CEPSTRUM - cepstrum and smoothed spectrum

The CEPSTRUM atom computes the real cepstrum or the cepstrum smoothed spectrum of the input-spectrum X. The input X must be (!) a logarithmic magnitude spectrum with length nX = 2M+1. If the inputs N and I are not connected, the real cepstrum is computed and the 1st half (nX-1 coefs.) is stored in Y. The cepstrum is multiplied with the scaling factor C (def.=1). If the input N (number of coefs.) is connected, a smoothed (filtered) spectrum is computed and stored in Y (nX samples). For the computation of the smoothed spectrum, the cepstrum coefficients with index I to I+N-1 are used (I>=0, N>0, I+N<=nX-1). The smoothing parameters N and I can be changed in each evaluation cycle.

Usage:

CEPSTRUM X N I C

Inputs:

X

A logarithmic magnitude spectrum.

N

The number of cepstrum coefficients (coefs.) for smoothing.

I

The index of 1st cepstrum coef. for smoothing=0.

C

The factor or shift-level; default=1(factor) or 0(dB).

Outputs:

Y

A real cepstrum (1st half) or smoothed/filtered spectrum.