mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-16 20:35:23 +00:00
143 lines
4.7 KiB
C
143 lines
4.7 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 Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "libavutil/common.h"
|
|
#include "libavutil/mem.h"
|
|
#include "config.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;
|
|
};
|
|
|
|
TimeFilter *ff_timefilter_new(double clock_period,
|
|
double feedback2_factor,
|
|
double feedback3_factor)
|
|
{
|
|
TimeFilter *self = av_mallocz(sizeof(TimeFilter));
|
|
self->clock_period = clock_period;
|
|
self->feedback2_factor = feedback2_factor;
|
|
self->feedback3_factor = feedback3_factor;
|
|
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 / period;
|
|
}
|
|
return self->cycle_time;
|
|
}
|
|
|
|
#ifdef TEST
|
|
#include "libavutil/lfg.h"
|
|
#define LFG_MAX ((1LL << 32) - 1)
|
|
|
|
int main(void)
|
|
{
|
|
AVLFG prng;
|
|
double n0, n1;
|
|
#define SAMPLES 1000
|
|
double ideal[SAMPLES];
|
|
double samples[SAMPLES];
|
|
for (n0 = 0; n0 < 40; n0 = 2 * n0 + 1) {
|
|
for (n1 = 0; n1 < 10; n1 = 2 * n1 + 1) {
|
|
double best_error = 1000000000;
|
|
double bestpar0 = 1;
|
|
double bestpar1 = 0.001;
|
|
int better, i;
|
|
|
|
av_lfg_init(&prng, 123);
|
|
for (i = 0; i < SAMPLES; i++) {
|
|
ideal[i] = 10 + i + n1 * i / (1000);
|
|
samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) / (LFG_MAX * 10LL);
|
|
}
|
|
|
|
do {
|
|
double par0, par1;
|
|
better = 0;
|
|
for (par0 = bestpar0 * 0.8; par0 <= bestpar0 * 1.21; par0 += bestpar0 * 0.05) {
|
|
for (par1 = bestpar1 * 0.8; par1 <= bestpar1 * 1.21; par1 += bestpar1 * 0.05) {
|
|
double error = 0;
|
|
TimeFilter *tf = ff_timefilter_new(1, par0, par1);
|
|
for (i = 0; i < SAMPLES; i++) {
|
|
double filtered;
|
|
filtered = ff_timefilter_update(tf, samples[i], 1);
|
|
error += (filtered - ideal[i]) * (filtered - ideal[i]);
|
|
}
|
|
ff_timefilter_destroy(tf);
|
|
if (error < best_error) {
|
|
best_error = error;
|
|
bestpar0 = par0;
|
|
bestpar1 = par1;
|
|
better = 1;
|
|
}
|
|
}
|
|
}
|
|
} while (better);
|
|
#if 0
|
|
double lastfil = 9;
|
|
TimeFilter *tf = ff_timefilter_new(1, bestpar0, bestpar1);
|
|
for (i = 0; i < SAMPLES; i++) {
|
|
double filtered;
|
|
filtered = ff_timefilter_update(tf, samples[i], 1);
|
|
printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i],
|
|
samples[FFMAX(i, 1)] - samples[FFMAX(i - 1, 0)], filtered - lastfil);
|
|
lastfil = filtered;
|
|
}
|
|
ff_timefilter_destroy(tf);
|
|
#else
|
|
printf(" [%f %f %9f]", bestpar0, bestpar1, best_error);
|
|
#endif
|
|
}
|
|
printf("\n");
|
|
}
|
|
return 0;
|
|
}
|
|
#endif
|