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ffmpeg / libavutil / rational.h @ 5b21bdab

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/*
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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 FFMPEG_RATIONAL_H
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#define FFMPEG_RATIONAL_H
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#include <stdint.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);
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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);
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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);
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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);
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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);
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#endif /* FFMPEG_RATIONAL_H */