1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/******************************************************************
iLBC Speech Coder ANSI-C Source Code
LPCencode.c
Copyright (c) 2001,
Global IP Sound AB.
All rights reserved.
******************************************************************/
#include <string.h>
#include "iLBC_define.h"
#include "helpfun.h"
#include "lsf.h"
#include "constants.h"
#include "LPCencode.h"
/*----------------------------------------------------------------*
* lpc analysis (subrutine to LPCencode)
*---------------------------------------------------------------*/
static void SimpleAnalysis(
float *lsf, /* (o) lsf coefficients */
float *data, /* (i) new data vector */
float *lpc_buffer /* (i) buffer containing old data */
){
int k, is;
float temp[BLOCKL], lp[LPC_FILTERORDER + 1];
float lp2[LPC_FILTERORDER + 1];
float r[LPC_FILTERORDER + 1];
memcpy(lpc_buffer+LPC_LOOKBACK,data,BLOCKL*sizeof(float));
/* No lookahead, last window is asymmetric */
for (k = 0; k < LPC_N; k++) {
is = LPC_LOOKBACK;
if (k < (LPC_N - 1)) {
lbc_window(temp, lpc_winTbl, lpc_buffer, BLOCKL);
} else {
lbc_window(temp, lpc_asymwinTbl, lpc_buffer + is, BLOCKL);
}
autocorr(r, temp, BLOCKL, LPC_FILTERORDER);
lbc_window(r, r, lpc_lagwinTbl, LPC_FILTERORDER + 1);
levdurb(lp, temp, r, LPC_FILTERORDER);
bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, LPC_FILTERORDER+1);
a2lsf(lsf + k*LPC_FILTERORDER, lp2);
}
memcpy(lpc_buffer, lpc_buffer+BLOCKL,
LPC_LOOKBACK*sizeof(float));
}
/*----------------------------------------------------------------*
* lsf interpolator and conversion from lsf to a coefficients
* (subrutine to SimpleInterpolateLSF)
*---------------------------------------------------------------*/
static void LSFinterpolate2a_enc(
float *a, /* (o) lpc coefficients */
float *lsf1,/* (i) first set of lsf coefficients */
float *lsf2,/* (i) second set of lsf coefficients */
float coef, /* (i) weighting coefficient to use between lsf1
and lsf2 */
long length /* (i) length of coefficient vectors */
){
float lsftmp[LPC_FILTERORDER];
interpolate(lsftmp, lsf1, lsf2, coef, length);
lsf2a(a, lsftmp);
}
/*----------------------------------------------------------------*
* lsf interpolator (subrutine to LPCencode)
*---------------------------------------------------------------*/
static void SimpleInterpolateLSF(
float *syntdenum, /* (o) the synthesis filter denominator
resulting from the quantized
interpolated lsf */
float *weightdenum, /* (o) the weighting filter denominator
resulting from the unquantized
interpolated lsf */
float *lsf, /* (i) the unquantized lsf coefficients */
float *lsfdeq, /* (i) the dequantized lsf coefficients */
float *lsfold, /* (i) the unquantized lsf coefficients of
the previous signal frame */
float *lsfdeqold, /* (i) the dequantized lsf coefficients of
the previous signal frame */
int length /* (i) should equate FILTERORDER */
){
int i, pos, lp_length;
float lp[LPC_FILTERORDER + 1], *lsf2, *lsfdeq2;
lsf2 = lsf + length;
lsfdeq2 = lsfdeq + length;
lp_length = length + 1;
/* subframe 1: Interpolation between old and first set of
lsf coefficients */
LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
lsf_weightTbl[0], length);
memcpy(syntdenum,lp,lp_length*sizeof(float));
LSFinterpolate2a_enc(lp, lsfold, lsf, lsf_weightTbl[0], length);
bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
/* subframe 2 to 6: Interpolation between first and second
set of lsf coefficients */
pos = lp_length;
for (i = 1; i < NSUB; i++) {
LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2,
lsf_weightTbl[i], length);
memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
LSFinterpolate2a_enc(lp, lsf, lsf2,
lsf_weightTbl[i], length);
bwexpand(weightdenum + pos, lp,
LPC_CHIRP_WEIGHTDENUM, lp_length);
pos += lp_length;
}
/* update memory */
memcpy(lsfold, lsf2, length*sizeof(float));
memcpy(lsfdeqold, lsfdeq2, length*sizeof(float));
}
/*----------------------------------------------------------------*
* lsf quantizer (subrutine to LPCencode)
*---------------------------------------------------------------*/
static void SimplelsfQ(
float *lsfdeq, /* (o) dequantized lsf coefficients
(dimension FILTERORDER) */
int *index, /* (o) quantization index */
float *lsf /* (i) the lsf coefficient vector to be
quantized (dimension FILTERORDER ) */
){
/* Quantize first LSF with memoryless split VQ */
SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT,
dim_lsfCbTbl, size_lsfCbTbl);
/* Quantize second LSF with memoryless split VQ */
SplitVQ(lsfdeq + LPC_FILTERORDER, index + LSF_NSPLIT,
lsf + LPC_FILTERORDER, lsfCbTbl, LSF_NSPLIT,
dim_lsfCbTbl, size_lsfCbTbl);
}
/*----------------------------------------------------------------*
* lpc encoder
*---------------------------------------------------------------*/
void LPCencode(
float *syntdenum, /* (i/o) synthesis filter coefficients
before/after encoding */
float *weightdenum, /* (i/o) weighting denumerator coefficients
before/after encoding */
int *lsf_index, /* (o) lsf quantization index */
float *data, /* (i) lsf coefficients to quantize */
iLBC_Enc_Inst_t *iLBCenc_inst
/* (i/o) the encoder state structure */
){
float lsf[LPC_FILTERORDER * LPC_N];
float lsfdeq[LPC_FILTERORDER * LPC_N];
int change=0;
SimpleAnalysis(lsf, data, (*iLBCenc_inst).lpc_buffer);
SimplelsfQ(lsfdeq, lsf_index, lsf);
change=LSF_check(lsfdeq, LPC_FILTERORDER, LPC_N);
SimpleInterpolateLSF(syntdenum, weightdenum,
lsf, lsfdeq, (*iLBCenc_inst).lsfold,
(*iLBCenc_inst).lsfdeqold, LPC_FILTERORDER);
}
|
