1mlib_SignalMelCepstral_F32(m3eMdLiIaBL)ib Library Funmcltiibo_nSsignalMelCepstral_F32(3MLIB)
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6 mlib_SignalMelCepstral_F32 - perform cepstral analysis in mel frequency
7 scale
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10 cc [ flag... ] file... -lmlib [ library... ]
11 #include <mlib.h>
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13 mlib_status mlib_SignalMelCepstral_F32(mlib_f32 *cepst,
14 const mlib_f32 *signal, void *state);
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18 The mlib_SignalMelCepstral_F32() function performs cepstral analysis in
19 mel frequency scale.
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22 The first two steps of mel scale cepstral analysis is the same as in
23 general cepstral anaysis. After the logarithm of the spectrum magnitude
24 is obtained, it is converted into mel frequency scale before the
25 inverse Fourier transform.
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27 +-----------+ +-----------+
28 | Linear | | Inverse |
29 ... ------>| to |------->| Fourier |----->
30 X'(k) | Mel Scale | X''(m) | Transform | c(n)
31 +-----------+ +-----------+
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35 where X'(k) is defined in linear frequency scale and X''(m) is defined
36 in mel frequency scale.
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39 The mel frequency scale is defined as following.
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41 freq_mel = melmul * LOG10(1 + freq_linear / meldiv)
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45 where freq_mel is the frequency in mel scale, freq_linear is the fre‐
46 quency in linear scale, melmul is the multiplying factor, muldiv is the
47 dividing factor.
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50 Optionally, a bank of band pass filters in linear frequency scale can
51 be used below the bank of band pass filters in mel frequency scale, as
52 shown below in linear frequency scale.
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54 0 f1 f2 f3 fp fp+1 fp+2 fp+3 fp+q
55 |---|---|---| ... |---|----|-----| ... | ... -> freq
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59 where fp = melbgn, fp+q = melend, p = nlinear, q = nmel; the filters
60 number 1 to p are defined in linear frequency scale which have equal
61 bandwidth in linear frequency scale; the filters number p+1 to p+q are
62 defined in mel frequency scale which have equal bandwidth in mel fre‐
63 quency scale and increasing bandwidth in linear frequency scale.
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66 See Digital Signal Processing by Alan V. Oppenheim and Ronald W.
67 Schafer, Prentice Hall, 1974.
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70 See Fundamentals of Speech Recognition by Lawrence Rabiner and Biing-
71 Hwang Juang, Prentice Hall, 1993.
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74 The function takes the following arguments:
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76 cepst The cepstral coefficients.
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79 signal The input signal vector.
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82 state Pointer to the internal state structure.
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86 The function returns MLIB_SUCCESS if successful. Otherwise it returns
87 MLIB_FAILURE.
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90 See attributes(5) for descriptions of the following attributes:
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95 ┌─────────────────────────────┬─────────────────────────────┐
96 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
97 ├─────────────────────────────┼─────────────────────────────┤
98 │Interface Stability │Committed │
99 ├─────────────────────────────┼─────────────────────────────┤
100 │MT-Level │MT-Safe │
101 └─────────────────────────────┴─────────────────────────────┘
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104 mlib_SignalMelCepstralInit_F32(3MLIB), mlib_SignalMelCepstral‐
105 Free_F32(3MLIB), attributes(5)
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109SunOS 5.11 2 Mar 2007 mlib_SignalMelCepstral_F32(3MLIB)