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 <inttypes.h>
25 
26  #define FRAC_BITS 14
27 #include "libavutil/common.h"
28 #include "mathops.h"
29 #include "lsp.h"
30 #include "libavcodec/mips/lsp_mips.h"
31 #include "libavutil/avassert.h"
32 
33  void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
34 {
35  int i, j;
36 
37  /* sort lsfq in ascending order. float bubble algorithm,
38  O(n) if data already sorted, O(n^2) - otherwise */
39  for(i=0; i<lp_order-1; i++)
40  for(j=i; j>=0 && lsfq[j] > lsfq[j+1]; j--)
41  FFSWAP(int16_t, lsfq[j], lsfq[j+1]);
42 
43  for(i=0; i<lp_order; i++)
44  {
45  lsfq[i] = FFMAX(lsfq[i], lsfq_min);
46  lsfq_min = lsfq[i] + lsfq_min_distance;
47  }
48  lsfq[lp_order-1] = FFMIN(lsfq[lp_order-1], lsfq_max);//Is warning required ?
49 }
50 
51  void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size)
52 {
53  int i;
54  float prev = 0.0;
55  for (i = 0; i < size; i++)
56  prev = lsf[i] = FFMAX(lsf[i], prev + min_spacing);
57 }
58 
59 
60 /* Cosine table: base_cos[i] = (1 << 15) * cos(i * PI / 64) */
61  static const int16_t tab_cos[65] =
62 {
63  32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
64  30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
65  23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
66  12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
67  1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
68  -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
69  -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
70  -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
71 };
72 
73  static int16_t ff_cos(uint16_t arg)
74 {
75  uint8_t offset= arg;
76  uint8_t ind = arg >> 8;
77 
78  av_assert2(arg <= 0x3fff);
79 
80  return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
81 }
82 
83  void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
84 {
85  int i;
86 
87  /* Convert LSF to LSP, lsp=cos(lsf) */
88  for(i=0; i<lp_order; i++)
89  // 20861 = 2.0 / PI in (0.15)
90  lsp[i] = ff_cos(lsf[i] * 20861 >> 15); // divide by PI and (0,13) -> (0,14)
91 }
92 
93  void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order)
94 {
95  int i;
96 
97  for(i = 0; i < lp_order; i++)
98  lsp[i] = cos(2.0 * M_PI * lsf[i]);
99 }
100 
101 /**
102  * @brief decodes polynomial coefficients from LSP
103  * @param[out] f decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
104  * @param lsp LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)
105  */
106  static void lsp2poly(int* f, const int16_t* lsp, int lp_half_order)
107 {
108  int i, j;
109 
110  f[0] = 0x400000; // 1.0 in (3.22)
111  f[1] = -lsp[0] * 256; // *2 and (0.15) -> (3.22)
112 
113  for(i=2; i<=lp_half_order; i++)
114  {
115  f[i] = f[i-2];
116  for(j=i; j>1; j--)
117  f[j] -= MULL(f[j-1], lsp[2*i-2], FRAC_BITS) - f[j-2];
118 
119  f[1] -= lsp[2*i-2] * 256;
120  }
121 }
122 
123  void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order)
124 {
125  int i;
126  int f1[MAX_LP_HALF_ORDER+1]; // (3.22)
127  int f2[MAX_LP_HALF_ORDER+1]; // (3.22)
128 
129  lsp2poly(f1, lsp , lp_half_order);
130  lsp2poly(f2, lsp+1, lp_half_order);
131 
132  /* 3.2.6 of G.729, Equations 25 and 26*/
133  lp[0] = 4096;
134  for(i=1; i<lp_half_order+1; i++)
135  {
136  int ff1 = f1[i] + f1[i-1]; // (3.22)
137  int ff2 = f2[i] - f2[i-1]; // (3.22)
138 
139  ff1 += 1 << 10; // for rounding
140  lp[i] = (ff1 + ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
141  lp[(lp_half_order << 1) + 1 - i] = (ff1 - ff2) >> 11; // divide by 2 and (3.22) -> (3.12)
142  }
143 }
144 
145  void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order)
146 {
147  int lp_half_order = lp_order >> 1;
148  double buf[MAX_LP_HALF_ORDER + 1];
149  double pa[MAX_LP_HALF_ORDER + 1];
150  double *qa = buf + 1;
151  int i,j;
152 
153  qa[-1] = 0.0;
154 
155  ff_lsp2polyf(lsp , pa, lp_half_order );
156  ff_lsp2polyf(lsp + 1, qa, lp_half_order - 1);
157 
158  for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) {
159  double paf = pa[i] * (1 + lsp[lp_order - 1]);
160  double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]);
161  lp[i-1] = (paf + qaf) * 0.5;
162  lp[j-1] = (paf - qaf) * 0.5;
163  }
164 
165  lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) *
166  pa[lp_half_order] * 0.5;
167 
168  lp[lp_order - 1] = lsp[lp_order - 1];
169 }
170 
171  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)
172 {
173  int16_t lsp_1st[MAX_LP_ORDER]; // (0.15)
174  int i;
175 
176  /* LSP values for first subframe (3.2.5 of G.729, Equation 24)*/
177  for(i=0; i<lp_order; i++)
178 #ifdef G729_BITEXACT
179  lsp_1st[i] = (lsp_2nd[i] >> 1) + (lsp_prev[i] >> 1);
180 #else
181  lsp_1st[i] = (lsp_2nd[i] + lsp_prev[i]) >> 1;
182 #endif
183 
184  ff_acelp_lsp2lpc(lp_1st, lsp_1st, lp_order >> 1);
185 
186  /* LSP values for second subframe (3.2.5 of G.729)*/
187  ff_acelp_lsp2lpc(lp_2nd, lsp_2nd, lp_order >> 1);
188 }
189 
190 #ifndef ff_lsp2polyf
191  void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order)
192 {
193  int i, j;
194 
195  f[0] = 1.0;
196  f[1] = -2 * lsp[0];
197  lsp -= 2;
198  for(i=2; i<=lp_half_order; i++)
199  {
200  double val = -2 * lsp[2*i];
201  f[i] = val * f[i-1] + 2*f[i-2];
202  for(j=i-1; j>1; j--)
203  f[j] += f[j-1] * val + f[j-2];
204  f[1] += val;
205  }
206 }
207 #endif /* ff_lsp2polyf */
208 
209  void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order)
210 {
211  double pa[MAX_LP_HALF_ORDER+1], qa[MAX_LP_HALF_ORDER+1];
212  float *lpc2 = lpc + (lp_half_order << 1) - 1;
213 
214  av_assert2(lp_half_order <= MAX_LP_HALF_ORDER);
215 
216  ff_lsp2polyf(lsp, pa, lp_half_order);
217  ff_lsp2polyf(lsp + 1, qa, lp_half_order);
218 
219  while (lp_half_order--) {
220  double paf = pa[lp_half_order+1] + pa[lp_half_order];
221  double qaf = qa[lp_half_order+1] - qa[lp_half_order];
222 
223  lpc [ lp_half_order] = 0.5*(paf+qaf);
224  lpc2[-lp_half_order] = 0.5*(paf-qaf);
225  }
226 }
227 
228  void ff_sort_nearly_sorted_floats(float *vals, int len)
229 {
230  int i,j;
231 
232  for (i = 0; i < len - 1; i++)
233  for (j = i; j >= 0 && vals[j] > vals[j+1]; j--)
234  FFSWAP(float, vals[j], vals[j+1]);
235 }
tab_cos
static const int16_t tab_cos[65]
Definition: lsp.c:61
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:145
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:228
MAX_LP_ORDER
#define MAX_LP_ORDER
Definition: lsp.h:95
val
static double val(void *priv, double ch)
Definition: aeval.c:76
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:33
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:93
f
#define f(width, name)
Definition: cbs_vp9.c:255
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:171
FRAC_BITS
#define FRAC_BITS
Definition: lsp.c:26
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:123
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:52
av_assert2
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:64
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
common.h
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:106
ff_lsp2polyf
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:191
ff_acelp_lsf2lsp
void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order)
Convert LSF to LSP.
Definition: lsp.c:83
ff_cos
static int16_t ff_cos(uint16_t arg)
Definition: lsp.c:73
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:209
MULL
#define MULL(a, b, s)
Definition: mathops.h:58
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:51
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