mlib_SignalCepstral_S16_AdmediaLib Library Fmlib_SignalCepstral_S16_Adp(3MLIB)NAMEmlib_SignalCepstral_S16_Adp - perform cepstral analysis
SYNOPSIS
cc [ flag... ] file... -lmlib [ library... ]
#include <mlib.h>
mlib_status mlib_SignalCepstral_S16_Adp(mlib_s16 *cepst,
mlib_s32 *cscale, const mlib_s16 *signal, void *state);
DESCRIPTION
The mlib_SignalCepstral_S16_Adp() function performs cepstral analysis.
The scaling factor of the output data will be calculated based on the
actual data.
The basic operations to compute the cepstrum is shown below.
+-----------+ +--------+ +-----------+
| Fourier | | | | Inverse |
----->| |----->| log|*| |------>| Fourier |----->
x(n) | Transform | X(k) | | X'(k) | Transform | c(n)
+-----------+ +--------+ +-----------+
where x(n) is the input signal and c(n) is its cepstrum. In mathemat‐
ics, they are
N-1 2*PI*k*n
X(k) = SUM x(n) * exp(-j*----------)
n=0 N
X'(k) = log|X(k)|
1 N-1 2*PI*k*n
c(n) = --- SUM X'(k) * exp(j*----------)
N n=0 N
Since X'(k) is real and even (symmetric), i.e.
X'(k) = X'(N - k)
the c(n) is real and the equation becomes Cosine transform.
1 N-1 2*PI*k*n
c(n) = --- SUM X'(k) * cos(----------)
N n=0 N
The cepstral coefficients in LPC is a special case of the above.
See Digital Signal Processing by Alan V. Oppenheim and Ronald W.
Schafer, Prentice Hall, 1974.
See Fundamentals of Speech Recognition by Lawrence Rabinerand Biing-
Hwang Juang, Prentice Hall, 1993.
PARAMETERS
The function takes the following arguments:
cepst The cepstral coefficients.
cscale The scaling factor of cepstral coefficients, where
actual_data = output_data * 2**(-scaling_factor).
signal The input signal vector, the signal samples are in Q15 for‐
mat.
state Pointer to the internal state structure.
RETURN VALUES
The function returns MLIB_SUCCESS if successful. Otherwise it returns
MLIB_FAILURE.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOmlib_SignalCepstralInit_S16(3MLIB), mlib_SignalCepstral_S16(3MLIB),
mlib_SignalCepstralFree_S16(3MLIB), attributes(5)SunOS 5.10 2 Mar 2007mlib_SignalCepstral_S16_Adp(3MLIB)
