rational.h
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上传日期:2022-07-11
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- /*
- * Rational numbers
- * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
- *
- * 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 rational.h
- * Rational numbers.
- * @author Michael Niedermayer <michaelni@gmx.at>
- */
- #ifndef AVUTIL_RATIONAL_H
- #define AVUTIL_RATIONAL_H
- //#include <stdint.h>
- //#include "common.h"
- /**
- * Rational number num/den.
- */
- typedef struct AVRational{
- int num; ///< numerator
- int den; ///< denominator
- } AVRational;
- /**
- * Compare two rationals.
- * @param a first rational
- * @param b second rational
- * @return 0 if a==b, 1 if a>b and -1 if a<b.
- */
- static inline int av_cmp_q(AVRational a, AVRational b){
- const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
- if(tmp) return (tmp>>63)|1;
- else return 0;
- }
- /**
- * Rational to double conversion.
- * @param a rational to convert
- * @return (double) a
- */
- static inline double av_q2d(AVRational a){
- return a.num / (double) a.den;
- }
- /**
- * Reduce a fraction.
- * This is useful for framerate calculations.
- * @param dst_nom destination numerator
- * @param dst_den destination denominator
- * @param nom source numerator
- * @param den source denominator
- * @param max the maximum allowed for dst_nom & dst_den
- * @return 1 if exact, 0 otherwise
- */
- int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max);
- /**
- * Multiplies two rationals.
- * @param b first rational.
- * @param c second rational.
- * @return b*c.
- */
- AVRational av_mul_q(AVRational b, AVRational c) av_const;
- /**
- * Divides one rational by another.
- * @param b first rational.
- * @param c second rational.
- * @return b/c.
- */
- AVRational av_div_q(AVRational b, AVRational c) av_const;
- /**
- * Adds two rationals.
- * @param b first rational.
- * @param c second rational.
- * @return b+c.
- */
- AVRational av_add_q(AVRational b, AVRational c) av_const;
- /**
- * Subtracts one rational from another.
- * @param b first rational.
- * @param c second rational.
- * @return b-c.
- */
- AVRational av_sub_q(AVRational b, AVRational c) av_const;
- /**
- * Converts a double precision floating point number to a rational.
- * @param d double to convert
- * @param max the maximum allowed numerator and denominator
- * @return (AVRational) d.
- */
- AVRational av_d2q(double d, int max) av_const;
- /**
- * @return 1 if q1 is nearer to p q than p q2, -1 if p q2 is nearer
- * than p q1, 0 if they have the same distance.
- */
- int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
- /**
- * Finds the nearest value in p q_list to p q.
- * @param q_list an array of rationals terminated by {0, 0}
- * @return the index of the nearest value found in the array
- */
- int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
- #endif /* AVUTIL_RATIONAL_H */