blob: 54901800ba6ad22fd33d6c8595400d378c7429ca
| 1 | /* |
| 2 | * copyright (c) 2005-2012 Michael Niedermayer <michaelni@gmx.at> |
| 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 | */ |
| 79 | enum 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 | */ |
| 118 | int64_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 | */ |
| 130 | int64_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 | * |
| 138 | * @see av_rescale(), av_rescale_q(), av_rescale_q_rnd() |
| 139 | */ |
| 140 | int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) av_const; |
| 141 | |
| 142 | /** |
| 143 | * Rescale a 64-bit integer by 2 rational numbers. |
| 144 | * |
| 145 | * The operation is mathematically equivalent to `a * bq / cq`. |
| 146 | * |
| 147 | * This function is equivalent to av_rescale_q_rnd() with #AV_ROUND_NEAR_INF. |
| 148 | * |
| 149 | * @see av_rescale(), av_rescale_rnd(), av_rescale_q_rnd() |
| 150 | */ |
| 151 | int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; |
| 152 | |
| 153 | /** |
| 154 | * Rescale a 64-bit integer by 2 rational numbers with specified rounding. |
| 155 | * |
| 156 | * The operation is mathematically equivalent to `a * bq / cq`. |
| 157 | * |
| 158 | * @see av_rescale(), av_rescale_rnd(), av_rescale_q() |
| 159 | */ |
| 160 | int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq, |
| 161 | enum AVRounding rnd) av_const; |
| 162 | |
| 163 | /** |
| 164 | * Compare two timestamps each in its own time base. |
| 165 | * |
| 166 | * @return One of the following values: |
| 167 | * - -1 if `ts_a` is before `ts_b` |
| 168 | * - 1 if `ts_a` is after `ts_b` |
| 169 | * - 0 if they represent the same position |
| 170 | * |
| 171 | * @warning |
| 172 | * The result of the function is undefined if one of the timestamps is outside |
| 173 | * the `int64_t` range when represented in the other's timebase. |
| 174 | */ |
| 175 | int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b); |
| 176 | |
| 177 | /** |
| 178 | * Compare the remainders of two integer operands divided by a common divisor. |
| 179 | * |
| 180 | * In other words, compare the least significant `log2(mod)` bits of integers |
| 181 | * `a` and `b`. |
| 182 | * |
| 183 | * @code{.c} |
| 184 | * av_compare_mod(0x11, 0x02, 0x10) < 0 // since 0x11 % 0x10 (0x1) < 0x02 % 0x10 (0x2) |
| 185 | * av_compare_mod(0x11, 0x02, 0x20) > 0 // since 0x11 % 0x20 (0x11) > 0x02 % 0x20 (0x02) |
| 186 | * @endcode |
| 187 | * |
| 188 | * @param a,b Operands |
| 189 | * @param mod Divisor; must be a power of 2 |
| 190 | * @return |
| 191 | * - a negative value if `a % mod < b % mod` |
| 192 | * - a positive value if `a % mod > b % mod` |
| 193 | * - zero if `a % mod == b % mod` |
| 194 | */ |
| 195 | int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); |
| 196 | |
| 197 | /** |
| 198 | * Rescale a timestamp while preserving known durations. |
| 199 | * |
| 200 | * This function is designed to be called per audio packet to scale the input |
| 201 | * timestamp to a different time base. Compared to a simple av_rescale_q() |
| 202 | * call, this function is robust against possible inconsistent frame durations. |
| 203 | * |
| 204 | * The `last` parameter is a state variable that must be preserved for all |
| 205 | * subsequent calls for the same stream. For the first call, `*last` should be |
| 206 | * initialized to #AV_NOPTS_VALUE. |
| 207 | * |
| 208 | * @param[in] in_tb Input time base |
| 209 | * @param[in] in_ts Input timestamp |
| 210 | * @param[in] fs_tb Duration time base; typically this is finer-grained |
| 211 | * (greater) than `in_tb` and `out_tb` |
| 212 | * @param[in] duration Duration till the next call to this function (i.e. |
| 213 | * duration of the current packet/frame) |
| 214 | * @param[in,out] last Pointer to a timestamp expressed in terms of |
| 215 | * `fs_tb`, acting as a state variable |
| 216 | * @param[in] out_tb Output timebase |
| 217 | * @return Timestamp expressed in terms of `out_tb` |
| 218 | * |
| 219 | * @note In the context of this function, "duration" is in term of samples, not |
| 220 | * seconds. |
| 221 | */ |
| 222 | int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb); |
| 223 | |
| 224 | /** |
| 225 | * Add a value to a timestamp. |
| 226 | * |
| 227 | * This function guarantees that when the same value is repeatly added that |
| 228 | * no accumulation of rounding errors occurs. |
| 229 | * |
| 230 | * @param[in] ts Input timestamp |
| 231 | * @param[in] ts_tb Input timestamp time base |
| 232 | * @param[in] inc Value to be added |
| 233 | * @param[in] inc_tb Time base of `inc` |
| 234 | */ |
| 235 | int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc); |
| 236 | |
| 237 | |
| 238 | /** |
| 239 | * @} |
| 240 | */ |
| 241 | |
| 242 | #endif /* AVUTIL_MATHEMATICS_H */ |
| 243 |