FFmpeg: libavcodec/lsp.c Source File

FFmpeg
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 FFmpeg.
8  *
9  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include <math.h>
25 
26 #include "config.h"
27 
28  #define FRAC_BITS 14
29 #include "libavutil/macros.h"
30 #include "mathops.h"
31 #include "lsp.h"
32 #if ARCH_MIPS
33 #include "libavcodec/mips/lsp_mips.h"
34 #endif /* ARCH_MIPS */
35 #include "libavutil/avassert.h"
36 
37  void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
38 {
39  int i, j;
40 
41  /* sort lsfq in ascending order. float bubble algorithm,
42  O(n) if data already sorted, O(n^2) - otherwise */
43  for(i=0; i<lp_order-1; i++)
44  for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
45  FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
46 
47  for(i=0; i<lp_order; i++)
48  {
49  lsfq[i] = FFMAX(lsfq[i], lsfq_min);
50  lsfq_min = lsfq[i] + lsfq_min_distance;
51  }
52  lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
53 }
54 
55  void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
56 {
57  int i;
58  float prev = 0.0;
59  for (i = 0; i < size; i++)
60  prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
61 }
62 
63 
64 /* Cosine table: base_cos[i] = (1 << 15) * cos(i * PI / 64) */
65  static const int16_t tab_cos[65] =
66 {
67  32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
68  30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
69  23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
70  12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
71  1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
72  -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
73  -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
74  -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
75 };
76 
77  static int16_t ff_cos(uint16_t arg)
78 {
79  uint8_t offset= arg;
80  uint8_t ind = arg >> 8;
81 
82  av_assert2(arg <= 0x3fff);
83 
84  return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
85 }
86 
87  void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
88 {
89  int i;
90 
91  /* Convert LSF to LSP, lsp=cos(lsf) */
92  for(i=0; i<lp_order; i++)
93  // 20861 = 2.0 / PI in (0.15)
94  lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
95 }
96 
97  void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
98 {
99  int i;
100 
101  for(i = 0; i < lp_order; i++)
102  lsp[i] = cos(2.0 * M_PI * lsf[i]);
103 }
104 
105 /**
106  * @brief decodes polynomial coefficients from LSP
107  * @param[out] f decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
108  * @param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
109  */
110  static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
111 {
112  int i, j;
113 
114  f[0] = 0x400000; // 1.0 in (3.22)
115  f[1] = -lsp[0] * 256; // *2 and (0.15) -> (3.22)
116 
117  for(i=2; i<=lp_half_order; i++)
118  {
119  f[i] = f[i-2];
120  for(j=i; j>1; j--)
121  f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
122 
123  f[1] -= lsp[2*i-2] * 256;
124  }
125 }
126 
127 #ifndef lsp2polyf
128 /**
129  * Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
130  * needed for LSP to LPC conversion.
131  * We only need to calculate the 6 first elements of the polynomial.
132  *
133  * @param lsp line spectral pairs in cosine domain
134  * @param[out] f polynomial input/output as a vector
135  *
136  * TIA/EIA/IS-733 2.4.3.3.5-1/2
137  */
138  static void lsp2polyf(const double *lsp, double *f, int lp_half_order)
139 {
140  f[0] = 1.0;
141  f[1] = -2 * lsp[0];
142  lsp -= 2;
143  for (int i = 2; i <= lp_half_order; i++) {
144  double val = -2 * lsp[2*i];
145  f[i] = val * f[i-1] + 2*f[i-2];
146  for (int j = i-1; j > 1; j--)
147  f[j] += f[j-1] * val + f[j-2];
148  f[1] += val;
149  }
150 }
151 #endif /* lsp2polyf */
152 
153  void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
154 {
155  int i;
156  int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
157  int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
158 
159  lsp2poly(f1, lsp , lp_half_order);
160  lsp2poly(f2, lsp+1, lp_half_order);
161 
162  /* 3.2.6 of G.729, Equations 25 and 26*/
163  lp[0] = 4096;
164  for(i=1; i<lp_half_order+1; i++)
165  {
166  int ff1 = f1[i] + f1[i-1]; // (3.22)
167  int ff2 = f2[i] - f2[i-1]; // (3.22)
168 
169  ff1 += 1 << 10; // for rounding
170  lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
171  lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
172  }
173 }
174 
175  void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
176 {
177  int lp_half_order = lp_order >> 1;
178  double buf[MAX_LP_HALF_ORDER + 1];
179  double pa[MAX_LP_HALF_ORDER + 1];
180  double *qa = buf + 1;
181  int i,j;
182 
183  qa[-1] = 0.0;
184 
185  lsp2polyf(lsp , pa, lp_half_order );
186  lsp2polyf(lsp + 1, qa, lp_half_order - 1);
187 
188  for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
189  double paf = pa[i] * (1 + lsp[lp_order - 1]);
190  double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
191  lp[i-1] = (paf + qaf) * 0.5;
192  lp[j-1] = (paf - qaf) * 0.5;
193  }
194 
195  lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
196  pa[lp_half_order] * 0.5;
197 
198  lp[lp_order - 1] = lsp[lp_order - 1];
199 }
200 
201  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)
202 {
203  int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
204  int i;
205 
206  /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
207  for(i=0; i<lp_order; i++)
208 #ifdef G729_BITEXACT
209  lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
210 #else
211  lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
212 #endif
213 
214  ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
215 
216  /* LSP values for second subframe (3.2.5 of G.729)*/
217  ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
218 }
219 
220  void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
221 {
222  double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
223  float *lpc2 = lpc + (lp_half_order << 1) - 1;
224 
225  av_assert2(lp_half_order <= MAX_LP_HALF_ORDER);
226 
227  lsp2polyf(lsp, pa, lp_half_order);
228  lsp2polyf(lsp + 1, qa, lp_half_order);
229 
230  while (lp_half_order--) {
231  double paf = pa[lp_half_order+1] + pa[lp_half_order];
232  double qaf = qa[lp_half_order+1] - qa[lp_half_order];
233 
234  lpc [ lp_half_order] = 0.5*(paf+qaf);
235  lpc2[-lp_half_order] = 0.5*(paf-qaf);
236  }
237 }
238 
239  void ff_sort_nearly_sorted_floats(float *vals, int len)
240 {
241  int i,j;
242 
243  for (i = 0; i < len - 1; i++)
244  for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
245  FFSWAP(float, vals[j], vals[j+1]);
246 }
tab_cos
static const int16_t tab_cos[65]
Definition: lsp.c:65
MAX_LP_HALF_ORDER
#define MAX_LP_HALF_ORDER
Definition: lsp.h:94
ff_amrwb_lsp2lpc
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:175
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
ff_sort_nearly_sorted_floats
void ff_sort_nearly_sorted_floats(float *vals, int len)
Sort values in ascending order.
Definition: lsp.c:239
MAX_LP_ORDER
#define MAX_LP_ORDER
Definition: lsp.h:95
macros.h
val
static double val(void *priv, double ch)
Definition: aeval.c:77
avassert.h
lsp_mips.h
ff_acelp_reorder_lsf
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:37
ff_acelp_lsf2lspd
void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
Floating point version of ff_acelp_lsf2lsp()
Definition: lsp.c:97
arg
const char * arg
Definition: jacosubdec.c:67
mathops.h
ff_acelp_lp_decode
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....
Definition: lsp.c:201
FRAC_BITS
#define FRAC_BITS
Definition: lsp.c:28
f
f
Definition: af_crystalizer.c:122
ff_acelp_lsp2lpc
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:153
size
int size
Definition: twinvq_data.h:10344
offset
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
Definition: writing_filters.txt:86
M_PI
#define M_PI
Definition: mathematics.h:67
av_assert2
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:67
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
len
int len
Definition: vorbis_enc_data.h:426
FFSWAP
#define FFSWAP(type, a, b)
Definition: macros.h:52
lsp.h
lsp2poly
static void lsp2poly(int *f, const int16_t *lsp, int lp_half_order)
decodes polynomial coefficients from LSP
Definition: lsp.c:110
ff_acelp_lsf2lsp
void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
Convert LSF to LSP.
Definition: lsp.c:87
ff_cos
static int16_t ff_cos(uint16_t arg)
Definition: lsp.c:77
ff_acelp_lspd2lpc
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:220
MULL
#define MULL(a, b, s)
Definition: mathops.h:57
lsp2polyf
static void 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:138
ff_set_min_dist_lsf
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:55
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