1 /*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #include <stdio.h>
20
21 #include "libavutil/common.h"
22 #include "libavutil/lfg.h"
23
24 #include "libavdevice/timefilter.h"
25
26 #define LFG_MAX ((1LL << 32) - 1)
27
main(void)28 int main(void)
29 {
30 AVLFG prng;
31 double n0, n1;
32 #define SAMPLES 1000
33 double ideal[SAMPLES];
34 double samples[SAMPLES];
35 double samplet[SAMPLES];
36 for (n0 = 0; n0 < 40; n0 = 2 * n0 + 1) {
37 for (n1 = 0; n1 < 10; n1 = 2 * n1 + 1) {
38 double best_error = 1000000000;
39 double bestpar0 = n0 ? 1 : 100000;
40 double bestpar1 = 1;
41 int better, i;
42
43 av_lfg_init(&prng, 123);
44 for (i = 0; i < SAMPLES; i++) {
45 samplet[i] = 10 + i + (av_lfg_get(&prng) < LFG_MAX/2 ? 0 : 0.999);
46 ideal[i] = samplet[i] + n1 * i / (1000);
47 samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) / (LFG_MAX * 10LL);
48 if(i && samples[i]<samples[i-1])
49 samples[i]=samples[i-1]+0.001;
50 }
51
52 do {
53 double par0, par1;
54 better = 0;
55 for (par0 = bestpar0 * 0.8; par0 <= bestpar0 * 1.21; par0 += bestpar0 * 0.05) {
56 for (par1 = bestpar1 * 0.8; par1 <= bestpar1 * 1.21; par1 += bestpar1 * 0.05) {
57 double error = 0;
58 TimeFilter *tf = ff_timefilter_new(1, par0, par1);
59 if (!tf) {
60 printf("Could not allocate memory for timefilter.\n");
61 exit(1);
62 }
63 for (i = 0; i < SAMPLES; i++) {
64 double filtered;
65 filtered = ff_timefilter_update(tf, samples[i], i ? (samplet[i] - samplet[i-1]) : 1);
66 if(filtered < 0 || filtered > 1000000000)
67 printf("filter is unstable\n");
68 error += (filtered - ideal[i]) * (filtered - ideal[i]);
69 }
70 ff_timefilter_destroy(tf);
71 if (error < best_error) {
72 best_error = error;
73 bestpar0 = par0;
74 bestpar1 = par1;
75 better = 1;
76 }
77 }
78 }
79 } while (better);
80 printf(" [%12f %11f %9f]", bestpar0, bestpar1, best_error);
81 }
82 printf("\n");
83 }
84 return 0;
85 }
86