Programmer Guide/Command Reference/EVAL/cepstrum: Difference between revisions
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;Usage 1:<code>cepstrum(<var>x</var>)</code> | ;Usage 1:<code>cepstrum(<var>x</var>)</code> | ||
:;<var>x</var>: a vector containing a log. amplitude spectrum | :;<var>x</var>: a vector containing a log. amplitude spectrum | ||
::*note: because | ::*note: because a radix-2 fft/ifft is used for the computation, the spectrum stored in ''x'' must be computed from a signal with <code>L=2^M</code> samples (<code>-> nrow(''x'')=L/2+1=2^M/2+1</code>). | ||
;Result 1:A vector with <code>L/2</code> values, containing the coefficients or the real cepstrum of ''x''. | ;Result 1:A vector with <code>L/2</code> values, containing the coefficients or the real cepstrum of ''x''. | ||
---- | ---- | ||
Revision as of 14:35, 12 April 2011
Compute the real cepstrum or the cepstrum smoothed/liftered spectrum of the logarithmic spectrum x.
- Usage 1
cepstrum(x)- x
- a vector containing a log. amplitude spectrum
- note: because a radix-2 fft/ifft is used for the computation, the spectrum stored in x must be computed from a signal with
L=2^Msamples (-> nrow(x)=L/2+1=2^M/2+1).
- note: because a radix-2 fft/ifft is used for the computation, the spectrum stored in x must be computed from a signal with
- Result 1
- A vector with
L/2values, containing the coefficients or the real cepstrum of x.
- Usage 2
cepstrum(x, m)- x
- a vector containing a log. amplitude spectrum
- m
- the number of coefficients to be used for smoothing; 0 < m <= L/2
- Description
-
- The real cepstrum c of x is computed.
- The coefficents m to
L/2-1of the cepstrum c are set to zero. - The smoothed spectrum is computed from the modified cepstrum c.
- Result 2
- A vector with same length as x, containing the smoothed spectrum.
- Usage 2
cepstrum(x, o, m)- x
- a vector containing a log. amplitude spectrum
- o
- the first coefficient to be used for smoothing; 0 < o < L/2
- m
- the number of coefficients to be used for smoothing; 0 < m <= L/2-o
- Description
-
- The real cepstrum c of x is computed.
- The coefficents 0 to o-1 and o+m to
L/2-1of the cepstrum c are set to zero. - The liftered spectrum is computed from the modified cepstrum c.
- Result 2
- A vector with same length as x, containing the liftered spectrum.
