/*
  framerate.h  -  framerate calculations

  Copyright (C)         CinelerraCV
    2007,               Christian Thaeter <ct@pipapo.org>

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef CINELERRA_FRAMERATE_H
#define CINELERRA_FRAMERATE_H

#include "lib/error.h"
#include "lib/time.h"

/**
 * framerates are defined as a rational number
 * for example NTSC with 29.97fps is {2997, 100}
 */
struct cinelerra_framerate_struct
{
  unsigned n; //numerator
  unsigned d; //denominator
};

typedef struct cinelerra_framerate_struct cinelerra_framerate;
typedef cinelerra_framerate* CinelerraFramerate;

typedef unsigned long cinelerra_framepos;

/**
 * Get the frame number of a given time at a given frame rate.
 * frame indexing starts with 1
 */
static inline cinelerra_framepos
cinelerra_framerate_frame_get_time (const CinelerraFramerate framerate, CinelerraTime time)
{
  REQUIRE (framerate);
  TODO ("if(!time)..");
  /* we add a magic microsecond for rounding, because of integer truncation frames may be calculated at most 1us earlier,
     the idea is to compensate odd framerates which fall out off microsecond precision.
   */
  return ((time->tv_sec * 1000000ULL + time->tv_usec + /*magic*/1) * framerate->n)/(framerate->d * 1000000ULL) + 1;
}

/**
 * Get the start time for a frame.
 * frame indexing starts with 1
 */
static inline CinelerraTime
cinelerra_framerate_time_get_time_frame (const CinelerraFramerate framerate,
                                         CinelerraTime time,
                                         cinelerra_framepos frame)
{
  REQUIRE (framerate);
  REQUIRE (frame>0);
  TODO ("if(!time)..");

  unsigned long long usec = (frame-1) * (framerate->d * 1000000ULL) / framerate->n;

  time->tv_sec = usec / 1000000;
  time->tv_usec = usec % 1000000;

  return time;
}

#endif