1/*
2 * copyright (c) 2005-2012 Michael Niedermayer <[email protected]>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21/**
22 * @file
23 * @addtogroup lavu_math
24 * Mathematical utilities for working with timestamp and time base.
25 */
26
27#ifndef AVUTIL_MATHEMATICS_H
28#define AVUTIL_MATHEMATICS_H
29
30#include <stdint.h>
31#include <math.h>
32#include "attributes.h"
33#include "rational.h"
34#include "intfloat.h"
35
36#ifndef M_E
37#define M_E 2.7182818284590452354 /* e */
38#endif
39#ifndef M_LN2
40#define M_LN2 0.69314718055994530942 /* log_e 2 */
41#endif
42#ifndef M_LN10
43#define M_LN10 2.30258509299404568402 /* log_e 10 */
44#endif
45#ifndef M_LOG2_10
46#define M_LOG2_10 3.32192809488736234787 /* log_2 10 */
47#endif
48#ifndef M_PHI
49#define M_PHI 1.61803398874989484820 /* phi / golden ratio */
50#endif
51#ifndef M_PI
52#define M_PI 3.14159265358979323846 /* pi */
53#endif
54#ifndef M_PI_2
55#define M_PI_2 1.57079632679489661923 /* pi/2 */
56#endif
57#ifndef M_SQRT1_2
58#define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
59#endif
60#ifndef M_SQRT2
61#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
62#endif
63#ifndef NAN
64#define NAN av_int2float(0x7fc00000)
65#endif
66#ifndef INFINITY
67#define INFINITY av_int2float(0x7f800000)
68#endif
69
70/**
71 * @addtogroup lavu_math
72 *
73 * @{
74 */
75
76/**
77 * Rounding methods.
78 */
79enum AVRounding {
80 AV_ROUND_ZERO = 0, ///< Round toward zero.
81 AV_ROUND_INF = 1, ///< Round away from zero.
82 AV_ROUND_DOWN = 2, ///< Round toward -infinity.
83 AV_ROUND_UP = 3, ///< Round toward +infinity.
84 AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
85 /**
86 * Flag telling rescaling functions to pass `INT64_MIN`/`MAX` through
87 * unchanged, avoiding special cases for #AV_NOPTS_VALUE.
88 *
89 * Unlike other values of the enumeration AVRounding, this value is a
90 * bitmask that must be used in conjunction with another value of the
91 * enumeration through a bitwise OR, in order to set behavior for normal
92 * cases.
93 *
94 * @code{.c}
95 * av_rescale_rnd(3, 1, 2, AV_ROUND_UP | AV_ROUND_PASS_MINMAX);
96 * // Rescaling 3:
97 * // Calculating 3 * 1 / 2
98 * // 3 / 2 is rounded up to 2
99 * // => 2
100 *
101 * av_rescale_rnd(AV_NOPTS_VALUE, 1, 2, AV_ROUND_UP | AV_ROUND_PASS_MINMAX);
102 * // Rescaling AV_NOPTS_VALUE:
103 * // AV_NOPTS_VALUE == INT64_MIN
104 * // AV_NOPTS_VALUE is passed through
105 * // => AV_NOPTS_VALUE
106 * @endcode
107 */
108 AV_ROUND_PASS_MINMAX = 8192,
109};
110
111/**
112 * Compute the greatest common divisor of two integer operands.
113 *
114 * @param a,b Operands
115 * @return GCD of a and b up to sign; if a >= 0 and b >= 0, return value is >= 0;
116 * if a == 0 and b == 0, returns 0.
117 */
118int64_t av_const av_gcd(int64_t a, int64_t b);
119
120/**
121 * Rescale a 64-bit integer with rounding to nearest.
122 *
123 * The operation is mathematically equivalent to `a * b / c`, but writing that
124 * directly can overflow.
125 *
126 * This function is equivalent to av_rescale_rnd() with #AV_ROUND_NEAR_INF.
127 *
128 * @see av_rescale_rnd(), av_rescale_q(), av_rescale_q_rnd()
129 */
130int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;
131
132/**
133 * Rescale a 64-bit integer with specified rounding.
134 *
135 * The operation is mathematically equivalent to `a * b / c`, but writing that
136 * directly can overflow, and does not support different rounding methods.
137 * If the result is not representable then INT64_MIN is returned.
138 *
139 * @see av_rescale(), av_rescale_q(), av_rescale_q_rnd()
140 */
141int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) av_const;
142
143/**
144 * Rescale a 64-bit integer by 2 rational numbers.
145 *
146 * The operation is mathematically equivalent to `a * bq / cq`.
147 *
148 * This function is equivalent to av_rescale_q_rnd() with #AV_ROUND_NEAR_INF.
149 *
150 * @see av_rescale(), av_rescale_rnd(), av_rescale_q_rnd()
151 */
152int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
153
154/**
155 * Rescale a 64-bit integer by 2 rational numbers with specified rounding.
156 *
157 * The operation is mathematically equivalent to `a * bq / cq`.
158 *
159 * @see av_rescale(), av_rescale_rnd(), av_rescale_q()
160 */
161int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq,
162 enum AVRounding rnd) av_const;
163
164/**
165 * Compare two timestamps each in its own time base.
166 *
167 * @return One of the following values:
168 * - -1 if `ts_a` is before `ts_b`
169 * - 1 if `ts_a` is after `ts_b`
170 * - 0 if they represent the same position
171 *
172 * @warning
173 * The result of the function is undefined if one of the timestamps is outside
174 * the `int64_t` range when represented in the other's timebase.
175 */
176int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
177
178/**
179 * Compare the remainders of two integer operands divided by a common divisor.
180 *
181 * In other words, compare the least significant `log2(mod)` bits of integers
182 * `a` and `b`.
183 *
184 * @code{.c}
185 * av_compare_mod(0x11, 0x02, 0x10) < 0 // since 0x11 % 0x10 (0x1) < 0x02 % 0x10 (0x2)
186 * av_compare_mod(0x11, 0x02, 0x20) > 0 // since 0x11 % 0x20 (0x11) > 0x02 % 0x20 (0x02)
187 * @endcode
188 *
189 * @param a,b Operands
190 * @param mod Divisor; must be a power of 2
191 * @return
192 * - a negative value if `a % mod < b % mod`
193 * - a positive value if `a % mod > b % mod`
194 * - zero if `a % mod == b % mod`
195 */
196int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod);
197
198/**
199 * Rescale a timestamp while preserving known durations.
200 *
201 * This function is designed to be called per audio packet to scale the input
202 * timestamp to a different time base. Compared to a simple av_rescale_q()
203 * call, this function is robust against possible inconsistent frame durations.
204 *
205 * The `last` parameter is a state variable that must be preserved for all
206 * subsequent calls for the same stream. For the first call, `*last` should be
207 * initialized to #AV_NOPTS_VALUE.
208 *
209 * @param[in] in_tb Input time base
210 * @param[in] in_ts Input timestamp
211 * @param[in] fs_tb Duration time base; typically this is finer-grained
212 * (greater) than `in_tb` and `out_tb`
213 * @param[in] duration Duration till the next call to this function (i.e.
214 * duration of the current packet/frame)
215 * @param[in,out] last Pointer to a timestamp expressed in terms of
216 * `fs_tb`, acting as a state variable
217 * @param[in] out_tb Output timebase
218 * @return Timestamp expressed in terms of `out_tb`
219 *
220 * @note In the context of this function, "duration" is in term of samples, not
221 * seconds.
222 */
223int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb);
224
225/**
226 * Add a value to a timestamp.
227 *
228 * This function guarantees that when the same value is repeatly added that
229 * no accumulation of rounding errors occurs.
230 *
231 * @param[in] ts Input timestamp
232 * @param[in] ts_tb Input timestamp time base
233 * @param[in] inc Value to be added
234 * @param[in] inc_tb Time base of `inc`
235 */
236int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc);
237
238
239/**
240 * @}
241 */
242
243#endif /* AVUTIL_MATHEMATICS_H */
244

source code of include/x86_64-linux-gnu/libavutil/mathematics.h