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 "lls.h"
34 
35 static void update_lls(LLSModel *m, const double *var)
36 {
37  int i, j;
38 
39  for (i = 0; i <= m->indep_count; i++) {
40  for (j = i; j <= m->indep_count; j++) {
41  m->covariance[i][j] += var[i] * var[j];
42  }
43  }
44 }
45 
46 void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
47 {
48  int i, j, k;
49  double (*factor)[MAX_VARS_ALIGN] = (void *) &m->covariance[1][0];
50  double (*covar) [MAX_VARS_ALIGN] = (void *) &m->covariance[1][1];
51  double *covar_y = m->covariance[0];
52  int count = m->indep_count;
53 
54  for (i = 0; i < count; i++) {
55  for (j = i; j < count; j++) {
56  double sum = covar[i][j];
57 
58  for (k = 0; k <= i-1; k++)
59  sum -= factor[i][k] * factor[j][k];
60 
61  if (i == j) {
62  if (sum < threshold)
63  sum = 1.0;
64  factor[i][i] = sqrt(sum);
65  } else {
66  factor[j][i] = sum / factor[i][i];
67  }
68  }
69  }
70 
71  for (i = 0; i < count; i++) {
72  double sum = covar_y[i + 1];
73 
74  for (k = 0; k <= i-1; k++)
75  sum -= factor[i][k] * m->coeff[0][k];
76 
77  m->coeff[0][i] = sum / factor[i][i];
78  }
79 
80  for (j = count - 1; j >= min_order; j--) {
81  for (i = j; i >= 0; i--) {
82  double sum = m->coeff[0][i];
83 
84  for (k = i + 1; k <= j; k++)
85  sum -= factor[k][i] * m->coeff[j][k];
86 
87  m->coeff[j][i] = sum / factor[i][i];
88  }
89 
90  m->variance[j] = covar_y[0];
91 
92  for (i = 0; i <= j; i++) {
93  double sum = m->coeff[j][i] * covar[i][i] - 2 * covar_y[i + 1];
94 
95  for (k = 0; k < i; k++)
96  sum += 2 * m->coeff[j][k] * covar[k][i];
97 
98  m->variance[j] += m->coeff[j][i] * sum;
99  }
100  }
101 }
102 
103 static double evaluate_lls(LLSModel *m, const double *param, int order)
104 {
105  int i;
106  double out = 0;
107 
108  for (i = 0; i <= order; i++)
109  out += param[i] * m->coeff[order][i];
110 
111  return out;
112 }
113 
114 av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
115 {
116  memset(m, 0, sizeof(LLSModel));
117  m->indep_count = indep_count;
118  m->update_lls = update_lls;
120  if (ARCH_X86)
121  ff_init_lls_x86(m);
122 }
LLSModel
Linear least squares model.
Definition: lls.h:37
out
FILE * out
Definition: movenc.c:54
MAX_VARS_ALIGN
#define MAX_VARS_ALIGN
Definition: lls.h:30
LLSModel::variance
double variance[MAX_VARS]
Definition: lls.h:40
ff_init_lls_x86
void ff_init_lls_x86(LLSModel *m)
Definition: lls_init.c:32
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:114
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:49
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:56
LLSModel::indep_count
int indep_count
Definition: lls.h:41
i
int i
Definition: input.c:406
internal.h
LLSModel::covariance
double covariance[(((32+1)+(4) -1)&~((4) -1))][MAX_VARS_ALIGN]
Definition: lls.h:38
evaluate_lls
static double evaluate_lls(LLSModel *m, const double *param, int order)
Definition: lls.c:103
update_lls
static void update_lls(LLSModel *m, const double *var)
Definition: lls.c:35
LLSModel::coeff
double coeff[32][MAX_VARS]
Definition: lls.h:39
factor
static const int factor[16]
Definition: vf_pp7.c:76
avpriv_solve_lls
void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
Definition: lls.c:46