rational.h 3.4 KB

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  1. /*
  2. * rational numbers
  3. * Copyright (c) 2003 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. * @file libavutil/rational.h
  23. * rational numbers
  24. * @author Michael Niedermayer <michaelni@gmx.at>
  25. */
  26. #ifndef AVUTIL_RATIONAL_H
  27. #define AVUTIL_RATIONAL_H
  28. #include <stdint.h>
  29. #include "common.h"
  30. /**
  31. * rational number numerator/denominator
  32. */
  33. typedef struct AVRational{
  34. int num; ///< numerator
  35. int den; ///< denominator
  36. } AVRational;
  37. /**
  38. * Compares two rationals.
  39. * @param a first rational
  40. * @param b second rational
  41. * @return 0 if a==b, 1 if a>b and -1 if a<b
  42. */
  43. static inline int av_cmp_q(AVRational a, AVRational b){
  44. const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
  45. if(tmp) return (tmp>>63)|1;
  46. else return 0;
  47. }
  48. /**
  49. * Converts rational to double.
  50. * @param a rational to convert
  51. * @return (double) a
  52. */
  53. static inline double av_q2d(AVRational a){
  54. return a.num / (double) a.den;
  55. }
  56. /**
  57. * Reduces a fraction.
  58. * This is useful for framerate calculations.
  59. * @param dst_num destination numerator
  60. * @param dst_den destination denominator
  61. * @param num source numerator
  62. * @param den source denominator
  63. * @param max the maximum allowed for dst_num & dst_den
  64. * @return 1 if exact, 0 otherwise
  65. */
  66. int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
  67. /**
  68. * Multiplies two rationals.
  69. * @param b first rational
  70. * @param c second rational
  71. * @return b*c
  72. */
  73. AVRational av_mul_q(AVRational b, AVRational c) av_const;
  74. /**
  75. * Divides one rational by another.
  76. * @param b first rational
  77. * @param c second rational
  78. * @return b/c
  79. */
  80. AVRational av_div_q(AVRational b, AVRational c) av_const;
  81. /**
  82. * Adds two rationals.
  83. * @param b first rational
  84. * @param c second rational
  85. * @return b+c
  86. */
  87. AVRational av_add_q(AVRational b, AVRational c) av_const;
  88. /**
  89. * Subtracts one rational from another.
  90. * @param b first rational
  91. * @param c second rational
  92. * @return b-c
  93. */
  94. AVRational av_sub_q(AVRational b, AVRational c) av_const;
  95. /**
  96. * Converts a double precision floating point number to a rational.
  97. * @param d double to convert
  98. * @param max the maximum allowed numerator and denominator
  99. * @return (AVRational) d
  100. */
  101. AVRational av_d2q(double d, int max) av_const;
  102. /**
  103. * @return 1 if \q1 is nearer to \p q than \p q2, -1 if \p q2 is nearer
  104. * than \p q1, 0 if they have the same distance.
  105. */
  106. int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
  107. /**
  108. * Finds the nearest value in \p q_list to \p q.
  109. * @param q_list an array of rationals terminated by {0, 0}
  110. * @return the index of the nearest value found in the array
  111. */
  112. int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
  113. #endif /* AVUTIL_RATIONAL_H */