80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
|
/*
|
||
|
|
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
|