Statistics
| Branch: | Revision:

ffmpeg / libavutil / rational.c @ 5d6e4c16

History | View | Annotate | Download (4.44 KB)

1 5ff85f1d Michael Niedermayer
/*
2 89c9ff50 Diego Biurrun
 * rational numbers
3 5ff85f1d Michael Niedermayer
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4
 *
5 b78e7197 Diego Biurrun
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8 5ff85f1d Michael Niedermayer
 * modify it under the terms of the GNU Lesser General Public
9
 * License as published by the Free Software Foundation; either
10 b78e7197 Diego Biurrun
 * version 2.1 of the License, or (at your option) any later version.
11 5ff85f1d Michael Niedermayer
 *
12 b78e7197 Diego Biurrun
 * FFmpeg is distributed in the hope that it will be useful,
13 5ff85f1d Michael Niedermayer
 * 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 b78e7197 Diego Biurrun
 * License along with FFmpeg; if not, write to the Free Software
19 5509bffa Diego Biurrun
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 5ff85f1d Michael Niedermayer
 */
21 115329f1 Diego Biurrun
22 5ff85f1d Michael Niedermayer
/**
23 ba87f080 Diego Biurrun
 * @file
24 89c9ff50 Diego Biurrun
 * rational numbers
25 5ff85f1d Michael Niedermayer
 * @author Michael Niedermayer <michaelni@gmx.at>
26
 */
27
28 b64b4134 Måns Rullgård
#include "avassert.h"
29 5ff85f1d Michael Niedermayer
//#include <math.h>
30
#include <limits.h>
31 115329f1 Diego Biurrun
32 5ff85f1d Michael Niedermayer
#include "common.h"
33 c11c2bc2 Alexander Strasser
#include "mathematics.h"
34 5ff85f1d Michael Niedermayer
#include "rational.h"
35
36 674bd4f6 Diego Biurrun
int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max){
37 c11c2bc2 Alexander Strasser
    AVRational a0={0,1}, a1={1,0};
38 674bd4f6 Diego Biurrun
    int sign= (num<0) ^ (den<0);
39
    int64_t gcd= av_gcd(FFABS(num), FFABS(den));
40 c11c2bc2 Alexander Strasser
41 6880edab Michael Niedermayer
    if(gcd){
42 674bd4f6 Diego Biurrun
        num = FFABS(num)/gcd;
43 6880edab Michael Niedermayer
        den = FFABS(den)/gcd;
44
    }
45 674bd4f6 Diego Biurrun
    if(num<=max && den<=max){
46
        a1= (AVRational){num, den};
47 c11c2bc2 Alexander Strasser
        den=0;
48
    }
49 115329f1 Diego Biurrun
50 c11c2bc2 Alexander Strasser
    while(den){
51 674bd4f6 Diego Biurrun
        uint64_t x      = num / den;
52
        int64_t next_den= num - den*x;
53 c11c2bc2 Alexander Strasser
        int64_t a2n= x*a1.num + a0.num;
54
        int64_t a2d= x*a1.den + a0.den;
55
56 3db1b8b5 Michael Niedermayer
        if(a2n > max || a2d > max){
57
            if(a1.num) x= (max - a0.num) / a1.num;
58
            if(a1.den) x= FFMIN(x, (max - a0.den) / a1.den);
59
60 674bd4f6 Diego Biurrun
            if (den*(2*x*a1.den + a0.den) > num*a1.den)
61 3db1b8b5 Michael Niedermayer
                a1 = (AVRational){x*a1.num + a0.num, x*a1.den + a0.den};
62
            break;
63
        }
64 c11c2bc2 Alexander Strasser
65
        a0= a1;
66
        a1= (AVRational){a2n, a2d};
67 674bd4f6 Diego Biurrun
        num= den;
68 c11c2bc2 Alexander Strasser
        den= next_den;
69
    }
70 b926b628 Michael Niedermayer
    av_assert2(av_gcd(a1.num, a1.den) <= 1U);
71 115329f1 Diego Biurrun
72 674bd4f6 Diego Biurrun
    *dst_num = sign ? -a1.num : a1.num;
73 c11c2bc2 Alexander Strasser
    *dst_den = a1.den;
74 115329f1 Diego Biurrun
75 c11c2bc2 Alexander Strasser
    return den==0;
76
}
77
78 5ff85f1d Michael Niedermayer
AVRational av_mul_q(AVRational b, AVRational c){
79
    av_reduce(&b.num, &b.den, b.num * (int64_t)c.num, b.den * (int64_t)c.den, INT_MAX);
80
    return b;
81
}
82
83
AVRational av_div_q(AVRational b, AVRational c){
84 79dc59b7 Michael Niedermayer
    return av_mul_q(b, (AVRational){c.den, c.num});
85 5ff85f1d Michael Niedermayer
}
86
87
AVRational av_add_q(AVRational b, AVRational c){
88
    av_reduce(&b.num, &b.den, b.num * (int64_t)c.den + c.num * (int64_t)b.den, b.den * (int64_t)c.den, INT_MAX);
89
    return b;
90
}
91
92
AVRational av_sub_q(AVRational b, AVRational c){
93 79dc59b7 Michael Niedermayer
    return av_add_q(b, (AVRational){-c.num, c.den});
94 5ff85f1d Michael Niedermayer
}
95
96
AVRational av_d2q(double d, int max){
97
    AVRational a;
98 79dc59b7 Michael Niedermayer
#define LOG2  0.69314718055994530941723212145817656807550013436025
99 1405782c Stefano Sabatini
    int exponent;
100
    int64_t den;
101 31fdd641 David Conrad
    if (isnan(d))
102
        return (AVRational){0,0};
103 6b4ed22f Stefano Sabatini
    if (isinf(d))
104
        return (AVRational){ d<0 ? -1:1, 0 };
105 1405782c Stefano Sabatini
    exponent = FFMAX( (int)(log(fabs(d) + 1e-20)/LOG2), 0);
106
    den = 1LL << (61 - exponent);
107 5ff85f1d Michael Niedermayer
    av_reduce(&a.num, &a.den, (int64_t)(d * den + 0.5), den, max);
108
109
    return a;
110
}
111 05b90fc0 Stefano Sabatini
112
int av_nearer_q(AVRational q, AVRational q1, AVRational q2)
113
{
114
    /* n/d is q, a/b is the median between q1 and q2 */
115
    int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den;
116
    int64_t b = 2 * (int64_t)q1.den * q2.den;
117
118
    /* rnd_up(a*d/b) > n => a*d/b > n */
119
    int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP);
120
121
    /* rnd_down(a*d/b) < n => a*d/b < n */
122
    int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN);
123
124
    return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1);
125
}
126
127
int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
128
{
129
    int i, nearest_q_idx = 0;
130
    for(i=0; q_list[i].den; i++)
131
        if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0)
132
            nearest_q_idx = i;
133
134
    return nearest_q_idx;
135
}
136 59a3bf0e Michael Niedermayer
137
#ifdef TEST
138
main(){
139
    AVRational a,b;
140
    for(a.num=-2; a.num<=2; a.num++){
141
        for(a.den=-2; a.den<=2; a.den++){
142
            for(b.num=-2; b.num<=2; b.num++){
143
                for(b.den=-2; b.den<=2; b.den++){
144
                    int c= av_cmp_q(a,b);
145
                    double d= av_q2d(a) == av_q2d(b) ? 0 : (av_q2d(a) - av_q2d(b));
146
                    if(d>0) d=1;
147
                    else if(d<0) d=-1;
148
                    else if(d != d) d= INT_MIN;
149
                    if(c!=d) av_log(0, AV_LOG_ERROR, "%d/%d %d/%d, %d %f\n", a.num, a.den, b.num, b.den, c,d);
150
                }
151
            }
152
        }
153
    }
154
}
155
#endif