Manual Pages for UNIX Operating System command usage for man mlib_SignalCepstral_S16

mediaLib Library Functions         mlib_SignalCepstral_S16(3MLIB)



NAME
     mlib_SignalCepstral_S16 - perform cepstral analysis

SYNOPSIS
     cc [ flag... ] file... -lmlib [ library... ]
     #include 

     mlib_status mlib_SignalCepstral_S16(mlib_s16 *cepst,
          mlib_s32 cscale, const mlib_s16 *signal, void *state);


DESCRIPTION
     The  mlib_SignalCepstral_S16()  function  performs  cepstral
     analysis.  The user supplied scaling factor will be used and
     the output will be saturated if necessary.


     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
     mathematics, 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(----------)



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mediaLib Library Functions         mlib_SignalCepstral_S16(3MLIB)



               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 format.


     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  attri-
     butes:
















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mediaLib Library Functions         mlib_SignalCepstral_S16(3MLIB)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|


SEE ALSO
     mlib_SignalCepstralInit_S16(3MLIB),
     mlib_SignalCepstral_S16_Adp(3MLIB),
     mlib_SignalCepstralFree_S16(3MLIB), attributes(5)










































SunOS 5.11           Last change: 2 Mar 2007                    3