timefilter.c 3.7 KB

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  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. #include <stdio.h>
  19. #include "libavutil/common.h"
  20. #include "libavutil/lfg.h"
  21. #include "libavdevice/timefilter.h"
  22. #define LFG_MAX ((1LL << 32) - 1)
  23. int main(void)
  24. {
  25. AVLFG prng;
  26. double n0, n1;
  27. #define SAMPLES 1000
  28. double ideal[SAMPLES];
  29. double samples[SAMPLES];
  30. double samplet[SAMPLES];
  31. for (n0 = 0; n0 < 40; n0 = 2 * n0 + 1) {
  32. for (n1 = 0; n1 < 10; n1 = 2 * n1 + 1) {
  33. double best_error = 1000000000;
  34. double bestpar0 = n0 ? 1 : 100000;
  35. double bestpar1 = 1;
  36. int better, i;
  37. av_lfg_init(&prng, 123);
  38. for (i = 0; i < SAMPLES; i++) {
  39. samplet[i] = 10 + i + (av_lfg_get(&prng) < LFG_MAX/2 ? 0 : 0.999);
  40. ideal[i] = samplet[i] + n1 * i / (1000);
  41. samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) / (LFG_MAX * 10LL);
  42. if(i && samples[i]<samples[i-1])
  43. samples[i]=samples[i-1]+0.001;
  44. }
  45. do {
  46. double par0, par1;
  47. better = 0;
  48. for (par0 = bestpar0 * 0.8; par0 <= bestpar0 * 1.21; par0 += bestpar0 * 0.05) {
  49. for (par1 = bestpar1 * 0.8; par1 <= bestpar1 * 1.21; par1 += bestpar1 * 0.05) {
  50. double error = 0;
  51. TimeFilter *tf = ff_timefilter_new(1, par0, par1);
  52. if (!tf) {
  53. printf("Could not allocate memory for timefilter.\n");
  54. exit(1);
  55. }
  56. for (i = 0; i < SAMPLES; i++) {
  57. double filtered;
  58. filtered = ff_timefilter_update(tf, samples[i], i ? (samplet[i] - samplet[i-1]) : 1);
  59. if(filtered < 0 || filtered > 1000000000)
  60. printf("filter is unstable\n");
  61. error += (filtered - ideal[i]) * (filtered - ideal[i]);
  62. }
  63. ff_timefilter_destroy(tf);
  64. if (error < best_error) {
  65. best_error = error;
  66. bestpar0 = par0;
  67. bestpar1 = par1;
  68. better = 1;
  69. }
  70. }
  71. }
  72. } while (better);
  73. #if 0
  74. double lastfil = 9;
  75. TimeFilter *tf = ff_timefilter_new(1, bestpar0, bestpar1);
  76. for (i = 0; i < SAMPLES; i++) {
  77. double filtered;
  78. filtered = ff_timefilter_update(tf, samples[i], 1);
  79. printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i],
  80. samples[FFMAX(i, 1)] - samples[FFMAX(i - 1, 0)], filtered - lastfil);
  81. lastfil = filtered;
  82. }
  83. ff_timefilter_destroy(tf);
  84. #else
  85. printf(" [%12f %11f %9f]", bestpar0, bestpar1, best_error);
  86. #endif
  87. }
  88. printf("\n");
  89. }
  90. return 0;
  91. }