FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavutil/pca.c
Date: 2026-09-30 10:56:58
Exec Total Coverage
Lines: 85 90 94.4%
Functions: 4 4 100.0%
Branches: 54 60 90.0%

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1 /*
2 * principal component analysis (PCA)
3 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * principal component analysis (PCA)
25 */
26
27 #include "common.h"
28 #include "mem.h"
29 #include "pca.h"
30
31 typedef struct PCA{
32 int count;
33 int n;
34 double *covariance;
35 double *mean;
36 double *z;
37 }PCA;
38
39 1 PCA *ff_pca_init(int n){
40 PCA *pca;
41
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1 if(n<=0)
42 ✗ return NULL;
43
44 1 pca= av_mallocz(sizeof(*pca));
45
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1 if (!pca)
46 ✗ return NULL;
47
48 1 pca->n= n;
49 1 pca->z = av_malloc_array(n, sizeof(*pca->z));
50 1 pca->count=0;
51 1 pca->covariance= av_calloc(n*n, sizeof(double));
52 1 pca->mean= av_calloc(n, sizeof(double));
53
54
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1 if (!pca->z || !pca->covariance || !pca->mean) {
55 ✗ ff_pca_free(pca);
56 ✗ return NULL;
57 }
58
59 1 return pca;
60 }
61
62 1 void ff_pca_free(PCA *pca){
63 1 av_freep(&pca->covariance);
64 1 av_freep(&pca->mean);
65 1 av_freep(&pca->z);
66 1 av_free(pca);
67 1 }
68
69 9000000 void ff_pca_add(PCA *pca, const double *v){
70 int i, j;
71 9000000 const int n= pca->n;
72
73
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81000000 for(i=0; i<n; i++){
74 72000000 pca->mean[i] += v[i];
75
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76 324000000 pca->covariance[j + i*n] += v[i]*v[j];
77 }
78 9000000 pca->count++;
79 9000000 }
80
81 1 int ff_pca(PCA *pca, double *eigenvector, double *eigenvalue){
82 int i, j, pass;
83 1 int k=0;
84 1 const int n= pca->n;
85 1 double *z = pca->z;
86
87 1 memset(eigenvector, 0, sizeof(double)*n*n);
88
89
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9 for(j=0; j<n; j++){
90 8 pca->mean[j] /= pca->count;
91 8 eigenvector[j + j*n] = 1.0;
92
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44 for(i=0; i<=j; i++){
93 36 pca->covariance[j + i*n] /= pca->count;
94 36 pca->covariance[j + i*n] -= pca->mean[i] * pca->mean[j];
95 36 pca->covariance[i + j*n] = pca->covariance[j + i*n];
96 }
97 8 eigenvalue[j]= pca->covariance[j + j*n];
98 8 z[j]= 0;
99 }
100
101
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8 for(pass=0; pass < 50; pass++){
102 8 double sum=0;
103
104
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105
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106 224 sum += fabs(pca->covariance[j + i*n]);
107
108
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8 if(sum == 0){
109
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9 for(i=0; i<n; i++){
110 8 double maxvalue= -1;
111
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44 for(j=i; j<n; j++){
112
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36 if(eigenvalue[j] > maxvalue){
113 16 maxvalue= eigenvalue[j];
114 16 k= j;
115 }
116 }
117 8 eigenvalue[k]= eigenvalue[i];
118 8 eigenvalue[i]= maxvalue;
119
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72 for(j=0; j<n; j++){
120 64 double tmp= eigenvector[k + j*n];
121 64 eigenvector[k + j*n]= eigenvector[i + j*n];
122 64 eigenvector[i + j*n]= tmp;
123 }
124 }
125 1 return pass;
126 }
127
128
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63 for(i=0; i<n; i++){
129
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252 for(j=i+1; j<n; j++){
130 196 double covar= pca->covariance[j + i*n];
131 double t,c,s,tau,theta, h;
132
133
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196 if(pass < 3 && fabs(covar) < sum / (5*n*n)) //FIXME why pass < 3
134 21 continue;
135
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175 if(fabs(covar) == 0.0) //FIXME should not be needed
136 26 continue;
137
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149 if(pass >=3 && fabs((eigenvalue[j]+z[j])/covar) > (1LL<<32) && fabs((eigenvalue[i]+z[i])/covar) > (1LL<<32)){
138 30 pca->covariance[j + i*n]=0.0;
139 30 continue;
140 }
141
142 119 h= (eigenvalue[j]+z[j]) - (eigenvalue[i]+z[i]);
143 119 theta=0.5*h/covar;
144 119 t=1.0/(fabs(theta)+sqrt(1.0+theta*theta));
145
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119 if(theta < 0.0) t = -t;
146
147 119 c=1.0/sqrt(1+t*t);
148 119 s=t*c;
149 119 tau=s/(1.0+c);
150 119 z[i] -= t*covar;
151 119 z[j] += t*covar;
152
153 #define ROTATE(a,i,j,k,l) {\
154 double g=a[j + i*n];\
155 double h=a[l + k*n];\
156 a[j + i*n]=g-s*(h+g*tau);\
157 a[l + k*n]=h+s*(g-h*tau); }
158
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1071 for(k=0; k<n; k++) {
159
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952 if(k!=i && k!=j){
160 714 ROTATE(pca->covariance,FFMIN(k,i),FFMAX(k,i),FFMIN(k,j),FFMAX(k,j))
161 }
162 952 ROTATE(eigenvector,k,i,k,j)
163 }
164 119 pca->covariance[j + i*n]=0.0;
165 }
166 }
167
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63 for (i=0; i<n; i++) {
168 56 eigenvalue[i] += z[i];
169 56 z[i]=0.0;
170 }
171 }
172
173 ✗ return -1;
174 }
175