www.pudn.com > ffmpeg-Sdk.rar > rational.h

/* 
 * Rational numbers 
 * Copyright (c) 2003 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 rational.h 
 * Rational numbers. 
 * @author Michael Niedermayer  
 */ 
 
#ifndef FFMPEG_RATIONAL_H 
#define FFMPEG_RATIONAL_H 
 
#include  
 
/** 
 * 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>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); 
 
/** 
 * Divides one rational by another. 
 * @param b first rational. 
 * @param c second rational. 
 * @return b/c. 
 */ 
AVRational av_div_q(AVRational b, AVRational c); 
 
/** 
 * Adds two rationals. 
 * @param b first rational. 
 * @param c second rational. 
 * @return b+c. 
 */ 
AVRational av_add_q(AVRational b, AVRational c); 
 
/** 
 * Subtracts one rational from another. 
 * @param b first rational. 
 * @param c second rational. 
 * @return b-c. 
 */ 
AVRational av_sub_q(AVRational b, AVRational c); 
 
/** 
 * 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); 
 
#endif /* FFMPEG_RATIONAL_H */