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