1mlib_SignalMelCepstral_S16(m3eMdLiIaBL)ib Library Funmcltiibo_nSsignalMelCepstral_S16(3MLIB)
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NAME

6       mlib_SignalMelCepstral_S16 - perform cepstral analysis in mel frequency
7       scale
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SYNOPSIS

10       cc [ flag... ] file... -lmlib [ library... ]
11       #include <mlib.h>
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13       mlib_status mlib_SignalMelCepstral_S16(mlib_s16 *cepst,
14            mlib_s32 cscale, const mlib_s16 *signal, void *state);
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DESCRIPTION

18       The mlib_SignalMelCepstral_S16() function performs cepstral analysis in
19       mel  frequency scale. The user supplied scaling factor will be used and
20       the output will be saturated if necessary.
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23       The first two steps of mel scale cepstral analysis is the  same  as  in
24       general cepstral anaysis. After the logarithm of the spectrum magnitude
25       is obtained, it is  converted  into  mel  frequency  scale  before  the
26       inverse Fourier transform.
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28                    +-----------+        +-----------+
29                    |  Linear   |        |  Inverse  |
30         ... ------>|    to     |------->|  Fourier  |----->
31              X'(k) | Mel Scale | X''(m) | Transform | c(n)
32                    +-----------+        +-----------+
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36       where  X'(k) is defined in linear frequency scale and X''(m) is defined
37       in mel frequency scale.
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40       The mel frequency scale is defined as following.
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42         freq_mel = melmul * LOG10(1 + freq_linear / meldiv)
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46       where freq_mel is the frequency in mel scale, freq_linear is  the  fre‐
47       quency in linear scale, melmul is the multiplying factor, muldiv is the
48       dividing factor.
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51       Optionally, a bank of band pass filters in linear frequency  scale  can
52       be  used below the bank of band pass filters in mel frequency scale, as
53       shown below in linear frequency scale.
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55         0   f1  f2  f3    fp  fp+1 fp+2  fp+3  fp+q
56         |---|---|---| ... |---|----|-----| ... | ... -> freq
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60       where fp = melbgn, fp+q = melend, p = nlinear, q =  nmel;  the  filters
61       number  1  to  p are defined in linear frequency scale which have equal
62       bandwidth in linear frequency scale; the filters number p+1 to p+q  are
63       defined  in  mel frequency scale which have equal bandwidth in mel fre‐
64       quency scale and increasing bandwidth in linear frequency scale.
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67       See Digital Signal Processing  by  Alan  V.  Oppenheim  and  Ronald  W.
68       Schafer, Prentice Hall, 1974.
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71       See  Fundamentals  of Speech Recognition by Lawrence Rabiner and Biing-
72       Hwang Juang, Prentice Hall, 1993.
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PARAMETERS

75       The function takes the following arguments:
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77       cepst     The cepstral coefficients.
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80       cscale    The  scaling   factor   of   cepstral   coefficients,   where
81                 actual_data = output_data * 2**(-scaling_factor).
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84       signal    The  input  signal vector, the signal samples are in Q15 for‐
85                 mat.
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88       state     Pointer to the internal state structure.
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RETURN VALUES

92       The function returns MLIB_SUCCESS if successful. Otherwise  it  returns
93       MLIB_FAILURE.
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ATTRIBUTES

96       See attributes(5) for descriptions of the following attributes:
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101       ┌─────────────────────────────┬─────────────────────────────┐
102       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
103       ├─────────────────────────────┼─────────────────────────────┤
104       │Interface Stability          │Committed                    │
105       ├─────────────────────────────┼─────────────────────────────┤
106       │MT-Level                     │MT-Safe                      │
107       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

110       mlib_SignalMelCepstralInit_S16(3MLIB),               mlib_SignalMelCep‐
111       stral_S16_Adp(3MLIB),            mlib_SignalMelCepstralFree_S16(3MLIB),
112       attributes(5)
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116SunOS 5.11                        2 Mar 2007 mlib_SignalMelCepstral_S16(3MLIB)
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