rational.h

mpeg4 video codec mpeg4 video codec

/*
 * Rational numbers
 * Copyright (c) 2003 Michael Niedermayer <[e-mail]>
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 this library; 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 <[e-mail]>
 */

#ifndef RATIONAL_H
#define RATIONAL_H

/**
 * Rational number num/den.
 */
typedef struct AVRational{
    int num; ///< numerator
    int den; ///< denominator
} AVRational;

/**
 * returns 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 (int)((tmp>>63)|1);
    else    return 0;
}

/**
 * converts the given AVRational to a double.
 */
static inline double av_q2d(AVRational a){
    return a.num / (double) a.den;
}

/**
 * reduce a fraction.
 * this is usefull for framerate calculations
 * @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);

AVRational av_mul_q(AVRational b, AVRational c);
AVRational av_div_q(AVRational b, AVRational c);
AVRational av_add_q(AVRational b, AVRational c);
AVRational av_sub_q(AVRational b, AVRational c);
AVRational av_d2q(double d, int max);

#endif // RATIONAL_H