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 
31 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
32 {
33  int i, j;
34 
35  /* sort lsfq in ascending order. float bubble agorithm,
36  O(n) if data already sorted, O(n^2) - otherwise */
37  for(i=0; i<lp_order-1; i++)
38  for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
39  FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
40 
41  for(i=0; i<lp_order; i++)
42  {
43  lsfq[i] = FFMAX(lsfq[i], lsfq_min);
44  lsfq_min = lsfq[i] + lsfq_min_distance;
45  }
46  lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
47 }
48 
49 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
50 {
51  int i;
52  float prev = 0.0;
53  for (i = 0; i < size; i++)
54  prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
55 }
56 
57 
58 /* Cosine table: base_cos[i] = (1 << 15) * cos(i * PI / 64) */
59 static const int16_t tab_cos[65] =
60 {
61  32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
62  30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
63  23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
64  12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
65  1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
66  -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
67  -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
68  -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
69 };
70 
71 static int16_t ff_cos(uint16_t arg)
72 {
73  uint8_t offset= arg;
74  uint8_t ind = arg >> 8;
75 
76  assert(arg <= 0x3fff);
77 
78  return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
79 }
80 
81 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
82 {
83  int i;
84 
85  /* Convert LSF to LSP, lsp=cos(lsf) */
86  for(i=0; i<lp_order; i++)
87  // 20861 = 2.0 / PI in (0.15)
88  lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
89 }
90 
91 void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
92 {
93  int i;
94 
95  for(i = 0; i < lp_order; i++)
96  lsp[i] = cos(2.0 * M_PI * lsf[i]);
97 }
98 
104 static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
105 {
106  int i, j;
107 
108  f[0] = 0x400000; // 1.0 in (3.22)
109  f[1] = -lsp[0] << 8; // *2 and (0.15) -> (3.22)
110 
111  for(i=2; i<=lp_half_order; i++)
112  {
113  f[i] = f[i-2];
114  for(j=i; j>1; j--)
115  f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
116 
117  f[1] -= lsp[2*i-2] << 8;
118  }
119 }
120 
121 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
122 {
123  int i;
124  int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
125  int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
126 
127  lsp2poly(f1, lsp , lp_half_order);
128  lsp2poly(f2, lsp+1, lp_half_order);
129 
130  /* 3.2.6 of G.729, Equations 25 and 26*/
131  lp[0] = 4096;
132  for(i=1; i<lp_half_order+1; i++)
133  {
134  int ff1 = f1[i] + f1[i-1]; // (3.22)
135  int ff2 = f2[i] - f2[i-1]; // (3.22)
136 
137  ff1 += 1 << 10; // for rounding
138  lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
139  lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
140  }
141 }
142 
143 void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
144 {
145  int lp_half_order = lp_order >> 1;
146  double buf[MAX_LP_HALF_ORDER + 1];
147  double pa[MAX_LP_HALF_ORDER + 1];
148  double *qa = buf + 1;
149  int i,j;
150 
151  qa[-1] = 0.0;
152 
153  ff_lsp2polyf(lsp , pa, lp_half_order );
154  ff_lsp2polyf(lsp + 1, qa, lp_half_order - 1);
155 
156  for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
157  double paf = pa[i] * (1 + lsp[lp_order - 1]);
158  double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
159  lp[i-1] = (paf + qaf) * 0.5;
160  lp[j-1] = (paf - qaf) * 0.5;
161  }
162 
163  lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
164  pa[lp_half_order] * 0.5;
165 
166  lp[lp_order - 1] = lsp[lp_order - 1];
167 }
168 
169 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)
170 {
171  int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
172  int i;
173 
174  /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
175  for(i=0; i<lp_order; i++)
176  lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
177 
178  ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
179 
180  /* LSP values for second subframe (3.2.5 of G.729)*/
181  ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
182 }
183 
184 void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
185 {
186  int i, j;
187 
188  f[0] = 1.0;
189  f[1] = -2 * lsp[0];
190  lsp -= 2;
191  for(i=2; i<=lp_half_order; i++)
192  {
193  double val = -2 * lsp[2*i];
194  f[i] = val * f[i-1] + 2*f[i-2];
195  for(j=i-1; j>1; j--)
196  f[j] += f[j-1] * val + f[j-2];
197  f[1] += val;
198  }
199 }
200 
201 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
202 {
203  double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
204  float *lpc2 = lpc + (lp_half_order << 1) - 1;
205 
206  assert(lp_half_order <= MAX_LP_HALF_ORDER);
207 
208  ff_lsp2polyf(lsp, pa, lp_half_order);
209  ff_lsp2polyf(lsp + 1, qa, lp_half_order);
210 
211  while (lp_half_order--) {
212  double paf = pa[lp_half_order+1] + pa[lp_half_order];
213  double qaf = qa[lp_half_order+1] - qa[lp_half_order];
214 
215  lpc [ lp_half_order] = 0.5*(paf+qaf);
216  lpc2[-lp_half_order] = 0.5*(paf-qaf);
217  }
218 }
219 
220 void ff_sort_nearly_sorted_floats(float *vals, int len)
221 {
222  int i,j;
223 
224  for (i = 0; i < len - 1; i++)
225  for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
226  FFSWAP(float, vals[j], vals[j+1]);
227 }
static const int16_t tab_cos[65]
Definition: lsp.c:59
int size
static void lsp2poly(int *f, const int16_t *lsp, int lp_half_order)
decodes polynomial coefficients from LSP
Definition: lsp.c:104
void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
Convert LSF to LSP.
Definition: lsp.c:81
static int16_t ff_cos(uint16_t arg)
Definition: lsp.c:71
void ff_acelp_reorder_lsf(int16_t *lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
(I.F) means fixed-point value with F fractional and I integer bits
Definition: lsp.c:31
#define MAX_LP_ORDER
Definition: lsp.h:95
void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients needed for LSP to LPC conversion...
Definition: lsp.c:184
uint8_t
void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
LSP to LP conversion (5.2.4 of AMR-WB)
Definition: lsp.c:143
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)
Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
Definition: lsp.c:169
void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
Reconstruct LPC coefficients from the line spectral pair frequencies.
Definition: lsp.c:201
external API header
void ff_acelp_lsp2lpc(int16_t *lp, const int16_t *lsp, int lp_half_order)
LSP to LP conversion (3.2.6 of G.729)
Definition: lsp.c:121
#define MAX_LP_HALF_ORDER
Definition: lsp.h:94
void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
Floating point version of ff_acelp_lsf2lsp()
Definition: lsp.c:91
#define FRAC_BITS
Definition: lsp.c:27
void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
Adjust the quantized LSFs so they are increasing and not too close.
Definition: lsp.c:49
void ff_sort_nearly_sorted_floats(float *vals, int len)
Sort values in ascending order.
Definition: lsp.c:220
int len
#define MULL(a, b, s)
Definition: mathops.h:55