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/** 23 * @file libavutil/rational.h 24 * rational numbers 25 * @author Michael Niedermayer <michaelni@gmx.at> 26 */ 27 28#ifndef AVUTIL_RATIONAL_H 29#define AVUTIL_RATIONAL_H 30 31#include <stdint.h> 32#include "common.h" 33 34/** 35 * rational number numerator/denominator 36 */ 37typedef struct AVRational{ 38 int num; ///< numerator 39 int den; ///< denominator 40} AVRational; 41 42/** 43 * Compares two rationals. 44 * @param a first rational 45 * @param b second rational 46 * @return 0 if a==b, 1 if a>b and -1 if a<b 47 */ 48static inline int av_cmp_q(AVRational a, AVRational b){ 49 const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den; 50 51 if(tmp) return (tmp>>63)|1; 52 else return 0; 53} 54 55/** 56 * Converts rational to double. 57 * @param a rational to convert 58 * @return (double) a 59 */ 60static inline double av_q2d(AVRational a){ 61 return a.num / (double) a.den; 62} 63 64/** 65 * Reduces a fraction. 66 * This is useful for framerate calculations. 67 * @param dst_num destination numerator 68 * @param dst_den destination denominator 69 * @param num source numerator 70 * @param den source denominator 71 * @param max the maximum allowed for dst_num & dst_den 72 * @return 1 if exact, 0 otherwise 73 */ 74int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max); 75 76/** 77 * Multiplies two rationals. 78 * @param b first rational 79 * @param c second rational 80 * @return b*c 81 */ 82AVRational av_mul_q(AVRational b, AVRational c) av_const; 83 84/** 85 * Divides one rational by another. 86 * @param b first rational 87 * @param c second rational 88 * @return b/c 89 */ 90AVRational av_div_q(AVRational b, AVRational c) av_const; 91 92/** 93 * Adds two rationals. 94 * @param b first rational 95 * @param c second rational 96 * @return b+c 97 */ 98AVRational av_add_q(AVRational b, AVRational c) av_const; 99 100/** 101 * Subtracts one rational from another. 102 * @param b first rational 103 * @param c second rational 104 * @return b-c 105 */ 106AVRational av_sub_q(AVRational b, AVRational c) av_const; 107 108/** 109 * Converts a double precision floating point number to a rational. 110 * @param d double to convert 111 * @param max the maximum allowed numerator and denominator 112 * @return (AVRational) d 113 */ 114AVRational av_d2q(double d, int max) av_const; 115 116/** 117 * @return 1 if \q1 is nearer to \p q than \p q2, -1 if \p q2 is nearer 118 * than \p q1, 0 if they have the same distance. 119 */ 120int av_nearer_q(AVRational q, AVRational q1, AVRational q2); 121 122/** 123 * Finds the nearest value in \p q_list to \p q. 124 * @param q_list an array of rationals terminated by {0, 0} 125 * @return the index of the nearest value found in the array 126 */ 127int av_find_nearest_q_idx(AVRational q, const AVRational* q_list); 128 129#endif /* AVUTIL_RATIONAL_H */ 130