mediaLib Library Functions         mlibSignalCepstralS16(3MLIB)



NAME
     mlibSignalCepstralS16 - perform cepstral analysis

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

     mlibstatus mlibSignalCepstralS16(mlibs16 *cepst,
          mlibs32 cscale, const mlibs16 *signal, void *state);


DESCRIPTION
     The  mlibSignalCepstralS16()  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) = logX(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         mlibSignalCepstralS16(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
               actualdata = outputdata * 2**(-scalingfactor).


     signal    The input signal vector, the signal samples are in
               Q15 format.


     state     Pointer to the internal state structure.


RETURN VALUES
     The function returns MLIBSUCES if  successful.  Otherwise
     it returns MLIBFAILURE.

ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:
















SunOS 5.11           Last change: 2 Mar 2007                    2






mediaLib Library Functions         mlibSignalCepstralS16(3MLIB)



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Committed                   
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     mlibSignalCepstralInitS16(3MLIB),
     mlibSignalCepstralS16Adp(3MLIB),
     mlibSignalCepstralFreeS16(3MLIB), attributes(5)










































SunOS 5.11           Last change: 2 Mar 2007                    3