FFmpeg
lls.c
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1 /*
2  * linear least squares model
3  *
4  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * linear least squares model
26  */
27 
28 #include <math.h>
29 #include <string.h>
30 
31 #include "attributes.h"
32 #include "internal.h"
33 #include "version.h"
34 #include "lls.h"
35 
36 static void update_lls(LLSModel *m, const double *var)
37 {
38  int i, j;
39 
40  for (i = 0; i <= m->indep_count; i++) {
41  for (j = i; j <= m->indep_count; j++) {
42  m->covariance[i][j] += var[i] * var[j];
43  }
44  }
45 }
46 
47 void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
48 {
49  int i, j, k;
50  double (*factor)[MAX_VARS_ALIGN] = (void *) &m->covariance[1][0];
51  double (*covar) [MAX_VARS_ALIGN] = (void *) &m->covariance[1][1];
52  double *covar_y = m->covariance[0];
53  int count = m->indep_count;
54 
55  for (i = 0; i < count; i++) {
56  for (j = i; j < count; j++) {
57  double sum = covar[i][j];
58 
59  for (k = 0; k <= i-1; k++)
60  sum -= factor[i][k] * factor[j][k];
61 
62  if (i == j) {
63  if (sum < threshold)
64  sum = 1.0;
65  factor[i][i] = sqrt(sum);
66  } else {
67  factor[j][i] = sum / factor[i][i];
68  }
69  }
70  }
71 
72  for (i = 0; i < count; i++) {
73  double sum = covar_y[i + 1];
74 
75  for (k = 0; k <= i-1; k++)
76  sum -= factor[i][k] * m->coeff[0][k];
77 
78  m->coeff[0][i] = sum / factor[i][i];
79  }
80 
81  for (j = count - 1; j >= min_order; j--) {
82  for (i = j; i >= 0; i--) {
83  double sum = m->coeff[0][i];
84 
85  for (k = i + 1; k <= j; k++)
86  sum -= factor[k][i] * m->coeff[j][k];
87 
88  m->coeff[j][i] = sum / factor[i][i];
89  }
90 
91  m->variance[j] = covar_y[0];
92 
93  for (i = 0; i <= j; i++) {
94  double sum = m->coeff[j][i] * covar[i][i] - 2 * covar_y[i + 1];
95 
96  for (k = 0; k < i; k++)
97  sum += 2 * m->coeff[j][k] * covar[k][i];
98 
99  m->variance[j] += m->coeff[j][i] * sum;
100  }
101  }
102 }
103 
104 static double evaluate_lls(LLSModel *m, const double *param, int order)
105 {
106  int i;
107  double out = 0;
108 
109  for (i = 0; i <= order; i++)
110  out += param[i] * m->coeff[order][i];
111 
112  return out;
113 }
114 
115 av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
116 {
117  memset(m, 0, sizeof(LLSModel));
118  m->indep_count = indep_count;
119  m->update_lls = update_lls;
121  if (ARCH_X86)
122  ff_init_lls_x86(m);
123 }
LLSModel
Linear least squares model.
Definition: lls.h:38
out
FILE * out
Definition: movenc.c:54
MAX_VARS_ALIGN
#define MAX_VARS_ALIGN
Definition: lls.h:31
LLSModel::variance
double variance[MAX_VARS]
Definition: lls.h:41
ff_init_lls_x86
void ff_init_lls_x86(LLSModel *m)
Definition: lls_init.c:31
av_cold
#define av_cold
Definition: attributes.h:90
lls.h
avpriv_init_lls
av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
Definition: lls.c:115
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
LLSModel::update_lls
void(* update_lls)(struct LLSModel *m, const double *var)
Take the outer-product of var[] with itself, and add to the covariance matrix.
Definition: lls.h:50
attributes.h
LLSModel::evaluate_lls
double(* evaluate_lls)(struct LLSModel *m, const double *var, int order)
Inner product of var[] and the LPC coefs.
Definition: lls.h:57
LLSModel::indep_count
int indep_count
Definition: lls.h:42
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
internal.h
LLSModel::covariance
double covariance[(((32+1)+(4) -1)&~((4) -1))][MAX_VARS_ALIGN]
Definition: lls.h:39
version.h
evaluate_lls
static double evaluate_lls(LLSModel *m, const double *param, int order)
Definition: lls.c:104
update_lls
static void update_lls(LLSModel *m, const double *var)
Definition: lls.c:36
LLSModel::coeff
double coeff[32][MAX_VARS]
Definition: lls.h:40
factor
static const int factor[16]
Definition: vf_pp7.c:75
avpriv_solve_lls
void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
Definition: lls.c:47