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130 lines
3.4 KiB
C
130 lines
3.4 KiB
C
/*
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* Rational numbers
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* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file rational.h
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* Rational numbers.
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* @author Michael Niedermayer <michaelni@gmx.at>
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*/
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#ifndef AVUTIL_RATIONAL_H
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#define AVUTIL_RATIONAL_H
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#include <stdint.h>
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#include "common.h"
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/**
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* Rational number num/den.
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*/
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typedef struct AVRational{
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int num; ///< numerator
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int den; ///< denominator
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} AVRational;
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/**
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* Compare two rationals.
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* @param a first rational
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* @param b second rational
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* @return 0 if a==b, 1 if a>b and -1 if a<b.
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*/
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static inline int av_cmp_q(AVRational a, AVRational b){
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const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
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if(tmp) return (tmp>>63)|1;
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else return 0;
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}
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/**
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* Rational to double conversion.
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* @param a rational to convert
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* @return (double) a
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*/
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static inline double av_q2d(AVRational a){
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return a.num / (double) a.den;
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}
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/**
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* Reduce a fraction.
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* This is useful for framerate calculations.
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* @param dst_nom destination numerator
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* @param dst_den destination denominator
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* @param nom source numerator
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* @param den source denominator
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* @param max the maximum allowed for dst_nom & dst_den
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* @return 1 if exact, 0 otherwise
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*/
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int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max);
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/**
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* Multiplies two rationals.
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* @param b first rational.
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* @param c second rational.
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* @return b*c.
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*/
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AVRational av_mul_q(AVRational b, AVRational c) av_const;
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/**
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* Divides one rational by another.
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* @param b first rational.
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* @param c second rational.
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* @return b/c.
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*/
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AVRational av_div_q(AVRational b, AVRational c) av_const;
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/**
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* Adds two rationals.
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* @param b first rational.
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* @param c second rational.
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* @return b+c.
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*/
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AVRational av_add_q(AVRational b, AVRational c) av_const;
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/**
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* Subtracts one rational from another.
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* @param b first rational.
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* @param c second rational.
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* @return b-c.
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*/
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AVRational av_sub_q(AVRational b, AVRational c) av_const;
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/**
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* Converts a double precision floating point number to a rational.
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* @param d double to convert
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* @param max the maximum allowed numerator and denominator
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* @return (AVRational) d.
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*/
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AVRational av_d2q(double d, int max) av_const;
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/**
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* @return 1 if \q1 is nearer to \p q than \p q2, -1 if \p q2 is nearer
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* than \p q1, 0 if they have the same distance.
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*/
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int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
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/**
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* Finds the nearest value in \p q_list to \p q.
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* @param q_list an array of rationals terminated by {0, 0}
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* @return the index of the nearest value found in the array
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*/
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int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
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#endif /* AVUTIL_RATIONAL_H */
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