| /* | |
| * copyright (c) 2005-2012 Michael Niedermayer <[email protected]> | |
| * | |
| * This file is part of FFmpeg. | |
| * | |
| * FFmpeg is free software; you can redistribute it and/or | |
| * modify it under the terms of the GNU Lesser General Public | |
| * License as published by the Free Software Foundation; either | |
| * version 2.1 of the License, or (at your option) any later version. | |
| * | |
| * FFmpeg is distributed in the hope that it will be useful, | |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| * Lesser General Public License for more details. | |
| * | |
| * You should have received a copy of the GNU Lesser General Public | |
| * License along with FFmpeg; if not, write to the Free Software | |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| */ | |
| /** | |
| * @file | |
| * @addtogroup lavu_math | |
| * Mathematical utilities for working with timestamp and time base. | |
| */ | |
| /** | |
| * @addtogroup lavu_math | |
| * | |
| * @{ | |
| */ | |
| /** | |
| * Rounding methods. | |
| */ | |
| enum AVRounding { | |
| AV_ROUND_ZERO = 0, ///< Round toward zero. | |
| AV_ROUND_INF = 1, ///< Round away from zero. | |
| AV_ROUND_DOWN = 2, ///< Round toward -infinity. | |
| AV_ROUND_UP = 3, ///< Round toward +infinity. | |
| AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero. | |
| /** | |
| * Flag telling rescaling functions to pass `INT64_MIN`/`MAX` through | |
| * unchanged, avoiding special cases for #AV_NOPTS_VALUE. | |
| * | |
| * Unlike other values of the enumeration AVRounding, this value is a | |
| * bitmask that must be used in conjunction with another value of the | |
| * enumeration through a bitwise OR, in order to set behavior for normal | |
| * cases. | |
| * | |
| * @code{.c} | |
| * av_rescale_rnd(3, 1, 2, AV_ROUND_UP | AV_ROUND_PASS_MINMAX); | |
| * // Rescaling 3: | |
| * // Calculating 3 * 1 / 2 | |
| * // 3 / 2 is rounded up to 2 | |
| * // => 2 | |
| * | |
| * av_rescale_rnd(AV_NOPTS_VALUE, 1, 2, AV_ROUND_UP | AV_ROUND_PASS_MINMAX); | |
| * // Rescaling AV_NOPTS_VALUE: | |
| * // AV_NOPTS_VALUE == INT64_MIN | |
| * // AV_NOPTS_VALUE is passed through | |
| * // => AV_NOPTS_VALUE | |
| * @endcode | |
| */ | |
| AV_ROUND_PASS_MINMAX = 8192, | |
| }; | |
| /** | |
| * Compute the greatest common divisor of two integer operands. | |
| * | |
| * @param a Operand | |
| * @param b Operand | |
| * @return GCD of a and b up to sign; if a >= 0 and b >= 0, return value is >= 0; | |
| * if a == 0 and b == 0, returns 0. | |
| */ | |
| int64_t av_const av_gcd(int64_t a, int64_t b); | |
| /** | |
| * Rescale a 64-bit integer with rounding to nearest. | |
| * | |
| * The operation is mathematically equivalent to `a * b / c`, but writing that | |
| * directly can overflow. | |
| * | |
| * This function is equivalent to av_rescale_rnd() with #AV_ROUND_NEAR_INF. | |
| * | |
| * @see av_rescale_rnd(), av_rescale_q(), av_rescale_q_rnd() | |
| */ | |
| int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const; | |
| /** | |
| * Rescale a 64-bit integer with specified rounding. | |
| * | |
| * The operation is mathematically equivalent to `a * b / c`, but writing that | |
| * directly can overflow, and does not support different rounding methods. | |
| * If the result is not representable then INT64_MIN is returned. | |
| * | |
| * @see av_rescale(), av_rescale_q(), av_rescale_q_rnd() | |
| */ | |
| int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) av_const; | |
| /** | |
| * Rescale a 64-bit integer by 2 rational numbers. | |
| * | |
| * The operation is mathematically equivalent to `a * bq / cq`. | |
| * | |
| * This function is equivalent to av_rescale_q_rnd() with #AV_ROUND_NEAR_INF. | |
| * | |
| * @see av_rescale(), av_rescale_rnd(), av_rescale_q_rnd() | |
| */ | |
| int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; | |
| /** | |
| * Rescale a 64-bit integer by 2 rational numbers with specified rounding. | |
| * | |
| * The operation is mathematically equivalent to `a * bq / cq`. | |
| * | |
| * @see av_rescale(), av_rescale_rnd(), av_rescale_q() | |
| */ | |
| int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq, | |
| enum AVRounding rnd) av_const; | |
| /** | |
| * Compare two timestamps each in its own time base. | |
| * | |
| * @return One of the following values: | |
| * - -1 if `ts_a` is before `ts_b` | |
| * - 1 if `ts_a` is after `ts_b` | |
| * - 0 if they represent the same position | |
| * | |
| * @warning | |
| * The result of the function is undefined if one of the timestamps is outside | |
| * the `int64_t` range when represented in the other's timebase. | |
| */ | |
| int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b); | |
| /** | |
| * Compare the remainders of two integer operands divided by a common divisor. | |
| * | |
| * In other words, compare the least significant `log2(mod)` bits of integers | |
| * `a` and `b`. | |
| * | |
| * @code{.c} | |
| * av_compare_mod(0x11, 0x02, 0x10) < 0 // since 0x11 % 0x10 (0x1) < 0x02 % 0x10 (0x2) | |
| * av_compare_mod(0x11, 0x02, 0x20) > 0 // since 0x11 % 0x20 (0x11) > 0x02 % 0x20 (0x02) | |
| * @endcode | |
| * | |
| * @param a Operand | |
| * @param b Operand | |
| * @param mod Divisor; must be a power of 2 | |
| * @return | |
| * - a negative value if `a % mod < b % mod` | |
| * - a positive value if `a % mod > b % mod` | |
| * - zero if `a % mod == b % mod` | |
| */ | |
| int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); | |
| /** | |
| * Rescale a timestamp while preserving known durations. | |
| * | |
| * This function is designed to be called per audio packet to scale the input | |
| * timestamp to a different time base. Compared to a simple av_rescale_q() | |
| * call, this function is robust against possible inconsistent frame durations. | |
| * | |
| * The `last` parameter is a state variable that must be preserved for all | |
| * subsequent calls for the same stream. For the first call, `*last` should be | |
| * initialized to #AV_NOPTS_VALUE. | |
| * | |
| * @param[in] in_tb Input time base | |
| * @param[in] in_ts Input timestamp | |
| * @param[in] fs_tb Duration time base; typically this is finer-grained | |
| * (greater) than `in_tb` and `out_tb` | |
| * @param[in] duration Duration till the next call to this function (i.e. | |
| * duration of the current packet/frame) | |
| * @param[in,out] last Pointer to a timestamp expressed in terms of | |
| * `fs_tb`, acting as a state variable | |
| * @param[in] out_tb Output timebase | |
| * @return Timestamp expressed in terms of `out_tb` | |
| * | |
| * @note In the context of this function, "duration" is in term of samples, not | |
| * seconds. | |
| */ | |
| int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb); | |
| /** | |
| * Add a value to a timestamp. | |
| * | |
| * This function guarantees that when the same value is repeatly added that | |
| * no accumulation of rounding errors occurs. | |
| * | |
| * @param[in] ts Input timestamp | |
| * @param[in] ts_tb Input timestamp time base | |
| * @param[in] inc Value to be added | |
| * @param[in] inc_tb Time base of `inc` | |
| */ | |
| int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc); | |
| /** | |
| * 0th order modified bessel function of the first kind. | |
| */ | |
| double av_bessel_i0(double x); | |
| /** | |
| * @} | |
| */ | |