h264_metadata: Add option to delete filler data
[libav.git] / libavdevice / timefilter.c
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1/*
2 * Delay Locked Loop based time filter
3 * Copyright (c) 2009 Samalyse
8507bde0 4 * Copyright (c) 2009 Michael Niedermayer
f982c6d8 5 * Author: Olivier Guilyardi <olivier samalyse com>
8507bde0 6 * Michael Niedermayer <michaelni gmx at>
f982c6d8 7 *
2912e87a 8 * This file is part of Libav.
f982c6d8 9 *
2912e87a 10 * Libav is free software; you can redistribute it and/or
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11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
14 *
2912e87a 15 * Libav is distributed in the hope that it will be useful,
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16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
2912e87a 21 * License along with Libav; if not, write to the Free Software
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22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
1d9c2dc8 25#include "libavutil/common.h"
0c5d78a8 26#include "libavutil/mem.h"
43992985 27
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28#include "timefilter.h"
29
30struct TimeFilter {
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31 // Delay Locked Loop data. These variables refer to mathematical
32 // concepts described in: http://www.kokkinizita.net/papers/usingdll.pdf
f982c6d8 33 double cycle_time;
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34 double feedback2_factor;
35 double feedback3_factor;
2e51dedd 36 double clock_period;
494065ca 37 int count;
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38};
39
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40TimeFilter *ff_timefilter_new(double clock_period,
41 double feedback2_factor,
42 double feedback3_factor)
f982c6d8 43{
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44 TimeFilter *self = av_mallocz(sizeof(TimeFilter));
45
46 if (!self)
47 return NULL;
48
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49 self->clock_period = clock_period;
50 self->feedback2_factor = feedback2_factor;
51 self->feedback3_factor = feedback3_factor;
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52 return self;
53}
54
55void ff_timefilter_destroy(TimeFilter *self)
56{
57 av_freep(&self);
58}
59
60void ff_timefilter_reset(TimeFilter *self)
61{
0c5d78a8 62 self->count = 0;
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63}
64
55b58598 65double ff_timefilter_update(TimeFilter *self, double system_time, double period)
f982c6d8 66{
494065ca 67 self->count++;
0c5d78a8 68 if (self->count == 1) {
0c5d78a8 69 self->cycle_time = system_time;
f982c6d8 70 } else {
28e947e4 71 double loop_error;
0c5d78a8 72 self->cycle_time += self->clock_period * period;
0c5d78a8 73 loop_error = system_time - self->cycle_time;
f982c6d8 74
3dc99a18 75 self->cycle_time += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
2e51dedd 76 self->clock_period += self->feedback3_factor * loop_error / period;
f982c6d8 77 }
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78 return self->cycle_time;
79}