ffmpeg.libavutil.rational source code

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 module ffmpeg.libavutil.rational;
22 import std.stdint;
23 
24 @nogc nothrow extern(C):
25 
26 /**
27  * @addtogroup lavu_math
28  * @{
29  */
30 
31 /**
32  * rational number numerator/denominator
33  */
34 struct AVRational {
35 	int num;
36 	int den;
37 	double q2d() const {
38 		return num/cast(double) den;
39 	}
40 } 
41 
42 
43 /**
44  * Compare two rationals.
45  * @param a first rational
46  * @param b second rational
47  * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
48  * values is of the form 0/0
49  */
50 static int av_cmp_q(AVRational a, AVRational b){
51     const int64_t tmp= a.num * cast(int64_t)b.den - b.num * cast(int64_t)a.den;
52 
53     if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
54     else if(b.den && a.den) return 0;
55     else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
56     else                    return int.min;
57 }
58 
59 /**
60  * Convert rational to double.
61  * @param a rational to convert
62  * @return (double) a
63  */
64 static double av_q2d(AVRational a){
65     return a.num / cast(double) a.den;
66 }
67 
68 /**
69  * Reduce a fraction.
70  * This is useful for framerate calculations.
71  * @param dst_num destination numerator
72  * @param dst_den destination denominator
73  * @param num source numerator
74  * @param den source denominator
75  * @param max the maximum allowed for dst_num & dst_den
76  * @return 1 if exact, 0 otherwise
77  */
78 int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
79  
80  /**
81  * Multiply two rationals.
82  * @param b first rational
83  * @param c second rational
84  * @return b*c
85  */
86 AVRational av_mul_q(AVRational b, AVRational c);
87 
88 /**
89  * Divide one rational by another.
90  * @param b first rational
91  * @param c second rational
92  * @return b/c
93  */
94 AVRational av_div_q(AVRational b, AVRational c);
95 
96 /**
97  * Add two rationals.
98  * @param b first rational
99  * @param c second rational
100  * @return b+c
101  */
102 AVRational av_add_q(AVRational b, AVRational c);
103 
104 /**
105  * Subtract one rational from another.
106  * @param b first rational
107  * @param c second rational
108  * @return b-c
109  */
110 AVRational av_sub_q(AVRational b, AVRational c);
111 
112 /**
113  * Convert a double precision floating point number to a rational.
114  * inf is expressed as {1,0} or {-1,0} depending on the sign.
115  *
116  * @param d double to convert
117  * @param max the maximum allowed numerator and denominator
118  * @return (AVRational) d
119  */
120 AVRational av_d2q(double d, int max);
121 
122 /**
123  * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
124  * than q1, 0 if they have the same distance.
125  */
126 int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
127 
128 /**
129  * Find the nearest value in q_list to q.
130  * @param q_list an array of rationals terminated by {0, 0}
131  * @return the index of the nearest value found in the array
132  */
133 int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);