mediaLib Library Functions      mlibSignalMelCepstralS16(3MLIB)



NAME
     mlibSignalMelCepstralS16 - perform  cepstral  analysis  in
     mel frequency scale

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

     mlibstatus mlibSignalMelCepstralS16(mlibs16 *cepst,
          mlibs32 cscale, const mlibs16 *signal, void *state);


DESCRIPTION
     The mlibSignalMelCepstralS16() function performs  cepstral
     analysis  in  mel frequency scale. The user supplied scaling
     factor will be used and the  output  will  be  saturated  if
     necessary.


     The first two steps of mel scale cepstral  analysis  is  the
     same  as in general cepstral anaysis. After the logarithm of
     the spectrum magnitude is obtained, it is converted into mel
     frequency scale before the inverse Fourier transform.

                  ]-----------]        ]-----------]
                    Linear             Inverse  
       ... ------>    to     ------->  Fourier  ----->
            X'(k)  Mel Scale  X''(m)  Transform  c(n)
                  ]-----------]        ]-----------]



     where X'(k) is defined in linear frequency scale and  X''(m)
     is defined in mel frequency scale.


     The mel frequency scale is defined as following.

       freqmel = melmul * LOG10(1 ] freqlinear / meldiv)



     where freqmel is the frequency in mel scale, freqlinear is
     the  frequency  in  linear  scale, melmul is the multiplying
     factor, muldiv is the dividing factor.


     Optionally, a bank of band pass filters in linear  frequency
     scale can be used below the bank of band pass filters in mel
     frequency scale, as shown below in linear frequency scale.

       0   f1  f2  f3    fp  fp]1 fp]2  fp]3  fp]q



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mediaLib Library Functions      mlibSignalMelCepstralS16(3MLIB)



       --------- ... ------------ ...  ... -> freq



     where fp = melbgn, fp]q = melend, p = nlinear, q = nmel; the
     filters  number 1 to p are defined in linear frequency scale
     which have equal bandwidth in linear  frequency  scale;  the
     filters number p]1 to p]q are defined in mel frequency scale
     which have  equal  bandwidth  in  mel  frequency  scale  and
     increasing bandwidth in linear frequency scale.


     See Digital Signal  Processing  by  Alan  V.  Oppenheim  and
     Ronald W. Schafer, Prentice Hall, 1974.


     See Fundamentals of Speech Recognition by  Lawrence  Rabiner
     and 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:












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mediaLib Library Functions      mlibSignalMelCepstralS16(3MLIB)



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


SEE ALSO
     mlibSignalMelCepstralInitS16(3MLIB),
     mlibSignalMelCepstralS16Adp(3MLIB),
     mlibSignalMelCepstralFreeS16(3MLIB), attributes(5)










































SunOS 5.11           Last change: 2 Mar 2007                    3