rational.h 2.94 KB
Newer Older
Michael Niedermayer's avatar
Michael Niedermayer committed
1 2 3 4
/*
 * Rational numbers
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
 *
5 6 7
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
Michael Niedermayer's avatar
Michael Niedermayer committed
8 9
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
Michael Niedermayer's avatar
Michael Niedermayer committed
11
 *
12
 * FFmpeg is distributed in the hope that it will be useful,
Michael Niedermayer's avatar
Michael Niedermayer committed
13 14 15 16 17
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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
Michael Niedermayer's avatar
Michael Niedermayer committed
20
 */
21

Michael Niedermayer's avatar
Michael Niedermayer committed
22 23 24 25 26 27
/**
 * @file rational.h
 * Rational numbers.
 * @author Michael Niedermayer <michaelni@gmx.at>
 */

28 29
#ifndef FFMPEG_RATIONAL_H
#define FFMPEG_RATIONAL_H
Michael Niedermayer's avatar
Michael Niedermayer committed
30

31 32
#include <stdint.h>

Michael Niedermayer's avatar
Michael Niedermayer committed
33 34 35
/**
 * Rational number num/den.
 */
Michael Niedermayer's avatar
Michael Niedermayer committed
36
typedef struct AVRational{
Michael Niedermayer's avatar
Michael Niedermayer committed
37 38
    int num; ///< numerator
    int den; ///< denominator
Michael Niedermayer's avatar
Michael Niedermayer committed
39 40
} AVRational;

Michael Niedermayer's avatar
Michael Niedermayer committed
41
/**
Dujardin Bernard's avatar
Dujardin Bernard committed
42 43 44 45
 * Compare two rationals.
 * @param a first rational
 * @param b second rational
 * @return 0 if a==b, 1 if a>b and -1 if a<b.
Michael Niedermayer's avatar
Michael Niedermayer committed
46
 */
Michael Niedermayer's avatar
Michael Niedermayer committed
47 48 49
static inline int av_cmp_q(AVRational a, AVRational b){
    const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;

Michael Niedermayer's avatar
Michael Niedermayer committed
50 51
    if(tmp) return (tmp>>63)|1;
    else    return 0;
Michael Niedermayer's avatar
Michael Niedermayer committed
52 53
}

Michael Niedermayer's avatar
Michael Niedermayer committed
54
/**
55
 * Rational to double conversion.
Dujardin Bernard's avatar
Dujardin Bernard committed
56 57
 * @param a rational to convert
 * @return (double) a
Michael Niedermayer's avatar
Michael Niedermayer committed
58
 */
Michael Niedermayer's avatar
Michael Niedermayer committed
59 60 61 62
static inline double av_q2d(AVRational a){
    return a.num / (double) a.den;
}

63
/**
Dujardin Bernard's avatar
Dujardin Bernard committed
64
 * Reduce a fraction.
65
 * This is useful for framerate calculations.
Dujardin Bernard's avatar
Dujardin Bernard committed
66 67 68 69
 * @param dst_nom destination numerator
 * @param dst_den destination denominator
 * @param nom source numerator
 * @param den source denominator
70 71 72 73 74
 * @param max the maximum allowed for dst_nom & dst_den
 * @return 1 if exact, 0 otherwise
 */
int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max);

75 76 77 78 79 80
/**
 * Multiplies two rationals.
 * @param b first rational.
 * @param c second rational.
 * @return b*c.
 */
81
AVRational av_mul_q(AVRational b, AVRational c) av_const;
82 83

/**
84
 * Divides one rational by another.
85 86 87 88
 * @param b first rational.
 * @param c second rational.
 * @return b/c.
 */
89
AVRational av_div_q(AVRational b, AVRational c) av_const;
90 91 92 93 94 95 96

/**
 * Adds two rationals.
 * @param b first rational.
 * @param c second rational.
 * @return b+c.
 */
97
AVRational av_add_q(AVRational b, AVRational c) av_const;
98 99

/**
100
 * Subtracts one rational from another.
101 102
 * @param b first rational.
 * @param c second rational.
103
 * @return b-c.
104
 */
105
AVRational av_sub_q(AVRational b, AVRational c) av_const;
106 107 108 109 110 111 112

/**
 * Converts a double precision floating point number to a rational.
 * @param d double to convert
 * @param max the maximum allowed numerator and denominator
 * @return (AVRational) d.
 */
113
AVRational av_d2q(double d, int max) av_const;
Michael Niedermayer's avatar
Michael Niedermayer committed
114

115
#endif /* FFMPEG_RATIONAL_H */