1mlib_SignalCepstral_S16_Adpm(e3dMiLaILBi)b Library Fumnlcitbi_oSnisgnalCepstral_S16_Adp(3MLIB)
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6 mlib_SignalCepstral_S16_Adp - perform cepstral analysis
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9 cc [ flag... ] file... -lmlib [ library... ]
10 #include <mlib.h>
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12 mlib_status mlib_SignalCepstral_S16_Adp(mlib_s16 *cepst,
13 mlib_s32 *cscale, const mlib_s16 *signal, void *state);
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17 The mlib_SignalCepstral_S16_Adp() function performs cepstral analysis.
18 The scaling factor of the output data will be calculated based on the
19 actual data.
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22 The basic operations to compute the cepstrum is shown below.
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24 +-----------+ +--------+ +-----------+
25 | Fourier | | | | Inverse |
26 ----->| |----->| log|*| |------>| Fourier |----->
27 x(n) | Transform | X(k) | | X'(k) | Transform | c(n)
28 +-----------+ +--------+ +-----------+
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32 where x(n) is the input signal and c(n) is its cepstrum. In mathemat‐
33 ics, they are
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35 N-1 2*PI*k*n
36 X(k) = SUM x(n) * exp(-j*----------)
37 n=0 N
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39 X'(k) = log|X(k)|
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41 1 N-1 2*PI*k*n
42 c(n) = --- SUM X'(k) * exp(j*----------)
43 N n=0 N
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47 Since X'(k) is real and even (symmetric), i.e.
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49 X'(k) = X'(N - k)
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53 the c(n) is real and the equation becomes Cosine transform.
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55 1 N-1 2*PI*k*n
56 c(n) = --- SUM X'(k) * cos(----------)
57 N n=0 N
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61 The cepstral coefficients in LPC is a special case of the above.
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64 See Digital Signal Processing by Alan V. Oppenheim and Ronald W.
65 Schafer, Prentice Hall, 1974.
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68 See Fundamentals of Speech Recognition by Lawrence Rabinerand Biing-
69 Hwang Juang, Prentice Hall, 1993.
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72 The function takes the following arguments:
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74 cepst The cepstral coefficients.
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77 cscale The scaling factor of cepstral coefficients, where
78 actual_data = output_data * 2**(-scaling_factor).
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81 signal The input signal vector, the signal samples are in Q15 for‐
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85 state Pointer to the internal state structure.
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89 The function returns MLIB_SUCCESS if successful. Otherwise it returns
90 MLIB_FAILURE.
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93 See attributes(5) for descriptions of the following attributes:
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98 ┌─────────────────────────────┬─────────────────────────────┐
99 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
100 ├─────────────────────────────┼─────────────────────────────┤
101 │Interface Stability │Committed │
102 ├─────────────────────────────┼─────────────────────────────┤
103 │MT-Level │MT-Safe │
104 └─────────────────────────────┴─────────────────────────────┘
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107 mlib_SignalCepstralInit_S16(3MLIB), mlib_SignalCepstral_S16(3MLIB),
108 mlib_SignalCepstralFree_S16(3MLIB), attributes(5)
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112SunOS 5.11 2 Mar 2007mlib_SignalCepstral_S16_Adp(3MLIB)