1mlib_SignalLPCAutoCorrel_F3m2e(d3iMaLLIiBb)Library Fmulnicbt_iSoingsnalLPCAutoCorrel_F32(3MLIB)
2
3
4
6 mlib_SignalLPCAutoCorrel_F32 - perform linear predictive coding with
7 autocorrelation method
8
10 cc [ flag... ] file... -lmlib [ library... ]
11 #include <mlib.h>
12
13 mlib_status mlib_SignalLPCAutoCorrel_F32(mlib_f32 *coeff,
14 const mlib_f32 *signal, void *state);
15
16
18 The mlib_SignalLPCAutoCorrel_F32() function performs linear predictive
19 coding with autocorrelation method.
20
21
22 In linear predictive coding (LPC) model, each speech sample is repre‐
23 sented as a linear combination of the past M samples.
24
25 M
26 s(n) = SUM a(i) * s(n-i) + G * u(n)
27 i=1
28
29
30
31 where s(*) is the speech signal, u(*) is the excitation signal, and G
32 is the gain constants, M is the order of the linear prediction filter.
33 Given s(*), the goal is to find a set of coefficient a(*) that mini‐
34 mizes the prediction error e(*).
35
36 M
37 e(n) = s(n) - SUM a(i) * s(n-i)
38 i=1
39
40
41
42 In autocorrelation method, the coefficients can be obtained by solving
43 following set of linear equations.
44
45 M
46 SUM a(i) * r(|i-k|) = r(k), k=1,...,M
47 i=1
48
49
50
51 where
52
53 N-k-1
54 r(k) = SUM s(j) * s(j+k)
55 j=0
56
57
58
59 are the autocorrelation coefficients of s(*), N is the length of the
60 input speech vector. r(0) is the energy of the speech signal.
61
62
63 Note that the autocorrelation matrix R is a Toeplitz matrix (symmetric
64 with all diagonal elements equal), and the equations can be solved
65 efficiently with Levinson-Durbin algorithm.
66
67
68 See Fundamentals of Speech Recognition by Lawrence Rabiner and Biing-
69 Hwang Juang, Prentice Hall, 1993.
70
72 The function takes the following arguments:
73
74 coeff The linear prediction coefficients.
75
76
77 signal The input signal vector.
78
79
80 state Pointer to the internal state structure.
81
82
84 The function returns MLIB_SUCCESS if successful. Otherwise it returns
85 MLIB_FAILURE.
86
88 See attributes(5) for descriptions of the following attributes:
89
90
91
92
93 ┌─────────────────────────────┬─────────────────────────────┐
94 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
95 ├─────────────────────────────┼─────────────────────────────┤
96 │Interface Stability │Committed │
97 ├─────────────────────────────┼─────────────────────────────┤
98 │MT-Level │MT-Safe │
99 └─────────────────────────────┴─────────────────────────────┘
100
102 mlib_SignalLPCAutoCorrelInit_F32(3MLIB), mlib_SignalLPCAutoCorrelGetEn‐
103 ergy_F32(3MLIB), mlib_SignalLPCAutoCorrelGetPARCOR_F32(3MLIB),
104 mlib_SignalLPCAutoCorrelFree_F32(3MLIB), attributes(5)
105
106
107
108SunOS 5.11 2 Mar 2007mlib_SignalLPCAutoCorrel_F32(3MLIB)