mirror of
https://github.com/jellyfin/jellyfin-ffmpeg.git
synced 2024-11-23 13:59:45 +00:00
96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
/*
|
|
* Delay Locked Loop based time filter
|
|
* Copyright (c) 2009 Samalyse
|
|
* Copyright (c) 2009 Michael Niedermayer
|
|
* Author: Olivier Guilyardi <olivier samalyse com>
|
|
* Michael Niedermayer <michaelni gmx at>
|
|
*
|
|
* 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
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <stddef.h>
|
|
|
|
#include "libavutil/macros.h"
|
|
#include "libavutil/mathematics.h"
|
|
#include "libavutil/mem.h"
|
|
|
|
#include "timefilter.h"
|
|
|
|
struct TimeFilter {
|
|
// Delay Locked Loop data. These variables refer to mathematical
|
|
// concepts described in: http://www.kokkinizita.net/papers/usingdll.pdf
|
|
double cycle_time;
|
|
double feedback2_factor;
|
|
double feedback3_factor;
|
|
double clock_period;
|
|
int count;
|
|
};
|
|
|
|
/* 1 - exp(-x) using a 3-order power series */
|
|
static double qexpneg(double x)
|
|
{
|
|
return 1 - 1 / (1 + x * (1 + x / 2 * (1 + x / 3)));
|
|
}
|
|
|
|
TimeFilter *ff_timefilter_new(double time_base,
|
|
double period,
|
|
double bandwidth)
|
|
{
|
|
TimeFilter *self = av_mallocz(sizeof(TimeFilter));
|
|
double o = 2 * M_PI * bandwidth * period * time_base;
|
|
|
|
if (!self)
|
|
return NULL;
|
|
|
|
self->clock_period = time_base;
|
|
self->feedback2_factor = qexpneg(M_SQRT2 * o);
|
|
self->feedback3_factor = qexpneg(o * o) / period;
|
|
return self;
|
|
}
|
|
|
|
void ff_timefilter_destroy(TimeFilter *self)
|
|
{
|
|
av_freep(&self);
|
|
}
|
|
|
|
void ff_timefilter_reset(TimeFilter *self)
|
|
{
|
|
self->count = 0;
|
|
}
|
|
|
|
double ff_timefilter_update(TimeFilter *self, double system_time, double period)
|
|
{
|
|
self->count++;
|
|
if (self->count == 1) {
|
|
self->cycle_time = system_time;
|
|
} else {
|
|
double loop_error;
|
|
self->cycle_time += self->clock_period * period;
|
|
loop_error = system_time - self->cycle_time;
|
|
|
|
self->cycle_time += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
|
|
self->clock_period += self->feedback3_factor * loop_error;
|
|
}
|
|
return self->cycle_time;
|
|
}
|
|
|
|
double ff_timefilter_eval(TimeFilter *self, double delta)
|
|
{
|
|
return self->cycle_time + self->clock_period * delta;
|
|
}
|