lsp.c
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1 /*
2  * LSP routines for ACELP-based codecs
3  *
4  * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet (QCELP decoder)
5  * Copyright (c) 2008 Vladimir Voroshilov
6  *
7  * This file is part of Libav.
8  *
9  * Libav is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * Libav is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include <inttypes.h>
25 
26 #include "avcodec.h"
27 #define FRAC_BITS 14
28 #include "mathops.h"
29 #include "lsp.h"
30 #include "celp_math.h"
31 
32 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
33 {
34  int i, j;
35 
36  /* sort lsfq in ascending order. float bubble agorithm,
37  O(n) if data already sorted, O(n^2) - otherwise */
38  for(i=0; i<lp_order-1; i++)
39  for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
40  FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
41 
42  for(i=0; i<lp_order; i++)
43  {
44  lsfq[i] = FFMAX(lsfq[i], lsfq_min);
45  lsfq_min = lsfq[i] + lsfq_min_distance;
46  }
47  lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
48 }
49 
50 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
51 {
52  int i;
53  float prev = 0.0;
54  for (i = 0; i < size; i++)
55  prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
56 }
57 
58 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
59 {
60  int i;
61 
62  /* Convert LSF to LSP, lsp=cos(lsf) */
63  for(i=0; i<lp_order; i++)
64  // 20861 = 2.0 / PI in (0.15)
65  lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
66 }
67 
68 void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
69 {
70  int i;
71 
72  for(i = 0; i < lp_order; i++)
73  lsp[i] = cos(2.0 * M_PI * lsf[i]);
74 }
75 
81 static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
82 {
83  int i, j;
84 
85  f[0] = 0x400000; // 1.0 in (3.22)
86  f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22)
87 
88  for(i=2; i<=lp_half_order; i++)
89  {
90  f[i] = f[i-2];
91  for(j=i; j>1; j--)
92  f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
93 
94  f[1] -= lsp[2*i-2] << 8;
95  }
96 }
97 
98 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
99 {
100  int i;
101  int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
102  int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
103 
104  lsp2poly(f1, lsp , lp_half_order);
105  lsp2poly(f2, lsp+1, lp_half_order);
106 
107  /* 3.2.6 of G.729, Equations 25 and 26*/
108  lp[0] = 4096;
109  for(i=1; i<lp_half_order+1; i++)
110  {
111  int ff1 = f1[i] + f1[i-1]; // (3.22)
112  int ff2 = f2[i] - f2[i-1]; // (3.22)
113 
114  ff1 += 1 << 10; // for rounding
115  lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
116  lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
117  }
118 }
119 
120 void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
121 {
122  int lp_half_order = lp_order >> 1;
123  double buf[MAX_LP_HALF_ORDER + 1];
124  double pa[MAX_LP_HALF_ORDER + 1];
125  double *qa = buf + 1;
126  int i,j;
127 
128  qa[-1] = 0.0;
129 
130  ff_lsp2polyf(lsp , pa, lp_half_order );
131  ff_lsp2polyf(lsp + 1, qa, lp_half_order - 1);
132 
133  for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
134  double paf = pa[i] * (1 + lsp[lp_order - 1]);
135  double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
136  lp[i-1] = (paf + qaf) * 0.5;
137  lp[j-1] = (paf - qaf) * 0.5;
138  }
139 
140  lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
141  pa[lp_half_order] * 0.5;
142 
143  lp[lp_order - 1] = lsp[lp_order - 1];
144 }
145 
146 void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order)
147 {
148  int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
149  int i;
150 
151  /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
152  for(i=0; i<lp_order; i++)
153  lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
154 
155  ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
156 
157  /* LSP values for second subframe (3.2.5 of G.729)*/
158  ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
159 }
160 
161 void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
162 {
163  int i, j;
164 
165  f[0] = 1.0;
166  f[1] = -2 * lsp[0];
167  lsp -= 2;
168  for(i=2; i<=lp_half_order; i++)
169  {
170  double val = -2 * lsp[2*i];
171  f[i] = val * f[i-1] + 2*f[i-2];
172  for(j=i-1; j>1; j--)
173  f[j] += f[j-1] * val + f[j-2];
174  f[1] += val;
175  }
176 }
177 
178 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
179 {
180  double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
181  float *lpc2 = lpc + (lp_half_order << 1) - 1;
182 
183  assert(lp_half_order <= MAX_LP_HALF_ORDER);
184 
185  ff_lsp2polyf(lsp, pa, lp_half_order);
186  ff_lsp2polyf(lsp + 1, qa, lp_half_order);
187 
188  while (lp_half_order--) {
189  double paf = pa[lp_half_order+1] + pa[lp_half_order];
190  double qaf = qa[lp_half_order+1] - qa[lp_half_order];
191 
192  lpc [ lp_half_order] = 0.5*(paf+qaf);
193  lpc2[-lp_half_order] = 0.5*(paf-qaf);
194  }
195 }
196 
197 void ff_sort_nearly_sorted_floats(float *vals, int len)
198 {
199  int i,j;
200 
201  for (i = 0; i < len - 1; i++)
202  for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
203  FFSWAP(float, vals[j], vals[j+1]);
204 }