/* * copyright (c) 2005-2012 Michael Niedermayer * * 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. */ #ifndef AVUTIL_MATHEMATICS_H #define AVUTIL_MATHEMATICS_H #include #include #include "attributes.h" #include "rational.h" #include "intfloat.h" #ifndef M_E # define M_E 2.7182818284590452354 /* e */ #endif #ifndef M_LN2 # define M_LN2 0.69314718055994530942 /* log_e 2 */ #endif #ifndef M_LN10 # define M_LN10 2.30258509299404568402 /* log_e 10 */ #endif #ifndef M_LOG2_10 # define M_LOG2_10 3.32192809488736234787 /* log_2 10 */ #endif #ifndef M_PHI # define M_PHI 1.61803398874989484820 /* phi / golden ratio */ #endif #ifndef M_PI # define M_PI 3.14159265358979323846 /* pi */ #endif #ifndef M_PI_2 # define M_PI_2 1.57079632679489661923 /* pi/2 */ #endif #ifndef M_SQRT1_2 # define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */ #endif #ifndef M_SQRT2 # define M_SQRT2 1.41421356237309504880 /* sqrt(2) */ #endif #ifndef NAN # define NAN av_int2float(0x7fc00000) #endif #ifndef INFINITY # define INFINITY av_int2float(0x7f800000) #endif /** * @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); /** * @} */ #endif /* AVUTIL_MATHEMATICS_H */