mathematics.h

播放H264文件的播放器

/*
 * copyright (c) 2005 Michael Niedermayer <[e-mail]>
 *
 * 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
 */

#ifndef AVUTIL_MATHEMATICS_H
#define AVUTIL_MATHEMATICS_H

#include <math.h>
#include "common.h"
#include "rational.h"

#ifndef M_E
#define M_E            2.7182818284590452354   /* e */
#endif
#ifndef M_LN2
#define M_LN2          0.69314718055994530942  /* log_e 2 */
#endif
#ifndef M_LN10
#define M_LN10         2.30258509299404568402  /* log_e 10 */
#endif
#ifndef M_PI
#define M_PI           3.14159265358979323846  /* pi */
#endif
#ifndef M_SQRT1_2
#define M_SQRT1_2      0.70710678118654752440  /* 1/sqrt(2) */
#endif

enum AVRounding {
    AV_ROUND_ZERO     = 0, ///< Round toward zero.
    AV_ROUND_INF      = 1, ///< Round away from zero.
    AV_ROUND_DOWN     = 2, ///< Round toward -infinity.
    AV_ROUND_UP       = 3, ///< Round toward +infinity.
    AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
};

int64_t av_const av_gcd(int64_t a, int64_t b);

/**
 * Rescales a 64-bit integer with rounding to nearest.
 * A simple a*b/c isn't possible as it can overflow.
 */
int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const;

/**
 * Rescales a 64-bit integer with specified rounding.
 * A simple a*b/c isn't possible as it can overflow.
 */
int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const;

/**
 * Rescales a 64-bit integer by 2 rational numbers.
 */
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;

#endif /* AVUTIL_MATHEMATICS_H */