ffmpeg / libavutil / rational.h @ 2ed6f399
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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 021101301 USA

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*/

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/**

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* @file libavutil/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 "attributes.h" 
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/**

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* rational number numerator/denominator

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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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* Compares 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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* Converts rational to double.

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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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* Reduces a fraction.

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* This is useful for framerate calculations.

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* @param dst_num destination numerator

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* @param dst_den destination denominator

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* @param num source numerator

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* @param den source denominator

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* @param max the maximum allowed for dst_num & 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_num, int *dst_den, int64_t num, 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 bc

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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 q than q2, 1 if q2 is nearer

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* than 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 q_list to 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 */ 