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comparison intercom/ilbc/LPCdecode.c @ 2:13be24d74cd2

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import intercom-0.4.1
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 09:57:52 +0200
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1:9cadc470e3da 2:13be24d74cd2
1
2 /******************************************************************
3
4 iLBC Speech Coder ANSI-C Source Code
5
6 LPC_decode.c
7
8 Copyright (C) The Internet Society (2004).
9 All Rights Reserved.
10
11 ******************************************************************/
12
13 #include <math.h>
14 #include <string.h>
15
16 #include "helpfun.h"
17 #include "lsf.h"
18 #include "iLBC_define.h"
19 #include "constants.h"
20
21 /*---------------------------------------------------------------*
22 * interpolation of lsf coefficients for the decoder
23 *--------------------------------------------------------------*/
24
25 void LSFinterpolate2a_dec(float *a, /* (o) lpc coefficients for a sub-frame */
26 float *lsf1, /* (i) first lsf coefficient vector */
27 float *lsf2, /* (i) second lsf coefficient vector */
28 float coef, /* (i) interpolation weight */
29 int length /* (i) length of lsf vectors */
30 )
31 {
32 float lsftmp[LPC_FILTERORDER];
33
34 interpolate(lsftmp, lsf1, lsf2, coef, length);
35 lsf2a(a, lsftmp);
36 }
37
38 /*---------------------------------------------------------------*
39 * obtain dequantized lsf coefficients from quantization index
40 *--------------------------------------------------------------*/
41
42 void SimplelsfDEQ(float *lsfdeq, /* (o) dequantized lsf coefficients */
43 int *index, /* (i) quantization index */
44 int lpc_n /* (i) number of LPCs */
45 )
46 {
47 int i, j, pos, cb_pos;
48
49
50
51
52
53 /* decode first LSF */
54
55 pos = 0;
56 cb_pos = 0;
57 for (i = 0; i < LSF_NSPLIT; i++) {
58 for (j = 0; j < dim_lsfCbTbl[i]; j++) {
59 lsfdeq[pos + j] = lsfCbTbl[cb_pos +
60 (long) (index[i]) * dim_lsfCbTbl[i] + j];
61 }
62 pos += dim_lsfCbTbl[i];
63 cb_pos += size_lsfCbTbl[i] * dim_lsfCbTbl[i];
64 }
65
66 if (lpc_n > 1) {
67
68 /* decode last LSF */
69
70 pos = 0;
71 cb_pos = 0;
72 for (i = 0; i < LSF_NSPLIT; i++) {
73 for (j = 0; j < dim_lsfCbTbl[i]; j++) {
74 lsfdeq[LPC_FILTERORDER + pos + j] =
75 lsfCbTbl[cb_pos +
76 (long) (index[LSF_NSPLIT + i]) * dim_lsfCbTbl[i] + j];
77 }
78 pos += dim_lsfCbTbl[i];
79 cb_pos += size_lsfCbTbl[i] * dim_lsfCbTbl[i];
80 }
81 }
82 }
83
84 /*----------------------------------------------------------------*
85 * obtain synthesis and weighting filters form lsf coefficients
86 *---------------------------------------------------------------*/
87
88 void DecoderInterpolateLSF(float *syntdenum, /* (o) synthesis filter coefficients */
89 float *weightdenum, /* (o) weighting denumerator
90 coefficients */
91 float *lsfdeq, /* (i) dequantized lsf coefficients */
92 int length, /* (i) length of lsf coefficient vector */
93 iLBC_Dec_Inst_t * iLBCdec_inst
94 /* (i) the decoder state structure */
95 )
96 {
97 int i, pos, lp_length;
98 float lp[LPC_FILTERORDER + 1], *lsfdeq2;
99
100
101
102
103
104
105 lsfdeq2 = lsfdeq + length;
106 lp_length = length + 1;
107
108 if (iLBCdec_inst->mode == 30) {
109 /* sub-frame 1: Interpolation between old and first */
110
111 LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq,
112 lsf_weightTbl_30ms[0], length);
113 memcpy(syntdenum, lp, lp_length * sizeof(float));
114 bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
115
116 /* sub-frames 2 to 6: interpolation between first
117 and last LSF */
118
119 pos = lp_length;
120 for (i = 1; i < 6; i++) {
121 LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2,
122 lsf_weightTbl_30ms[i], length);
123 memcpy(syntdenum + pos, lp, lp_length * sizeof(float));
124 bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
125 pos += lp_length;
126 }
127 } else {
128 pos = 0;
129 for (i = 0; i < iLBCdec_inst->nsub; i++) {
130 LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold,
131 lsfdeq, lsf_weightTbl_20ms[i], length);
132 memcpy(syntdenum + pos, lp, lp_length * sizeof(float));
133 bwexpand(weightdenum + pos, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
134 pos += lp_length;
135 }
136 }
137
138 /* update memory */
139
140 if (iLBCdec_inst->mode == 30)
141 memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2, length * sizeof(float));
142 else
143 memcpy(iLBCdec_inst->lsfdeqold, lsfdeq, length * sizeof(float));
144
145 }

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