Manual Pages for UNIX Operating System command usage for man mlib_SignalMelCepstral_S16

mediaLib Library Functions      mlib_SignalMelCepstral_S16(3MLIB)



NAME
     mlib_SignalMelCepstral_S16 - perform  cepstral  analysis  in
     mel frequency scale

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

     mlib_status mlib_SignalMelCepstral_S16(mlib_s16 *cepst,
          mlib_s32 cscale, const mlib_s16 *signal, void *state);


DESCRIPTION
     The mlib_SignalMelCepstral_S16() 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.

       freq_mel = melmul * LOG10(1 + freq_linear / meldiv)



     where freq_mel is the frequency in mel scale, freq_linear 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      mlib_SignalMelCepstral_S16(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
               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_SignalMelCepstral_S16(3MLIB)



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


SEE ALSO
     mlib_SignalMelCepstralInit_S16(3MLIB),
     mlib_SignalMelCepstral_S16_Adp(3MLIB),
     mlib_SignalMelCepstralFree_S16(3MLIB), attributes(5)










































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