h264_metadata: Add option to delete filler data
[libav.git] / libavdevice / timefilter.c
1 /*
2 * Delay Locked Loop based time filter
3 * Copyright (c) 2009 Samalyse
4 * Copyright (c) 2009 Michael Niedermayer
5 * Author: Olivier Guilyardi <olivier samalyse com>
6 * Michael Niedermayer <michaelni gmx at>
7 *
8 * This file is part of Libav.
9 *
10 * Libav is free software; you can redistribute it and/or
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 *
15 * Libav is distributed in the hope that it will be useful,
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
21 * License along with Libav; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25 #include "libavutil/common.h"
26 #include "libavutil/mem.h"
27
28 #include "timefilter.h"
29
30 struct TimeFilter {
31 // Delay Locked Loop data. These variables refer to mathematical
32 // concepts described in: http://www.kokkinizita.net/papers/usingdll.pdf
33 double cycle_time;
34 double feedback2_factor;
35 double feedback3_factor;
36 double clock_period;
37 int count;
38 };
39
40 TimeFilter *ff_timefilter_new(double clock_period,
41 double feedback2_factor,
42 double feedback3_factor)
43 {
44 TimeFilter *self = av_mallocz(sizeof(TimeFilter));
45
46 if (!self)
47 return NULL;
48
49 self->clock_period = clock_period;
50 self->feedback2_factor = feedback2_factor;
51 self->feedback3_factor = feedback3_factor;
52 return self;
53 }
54
55 void ff_timefilter_destroy(TimeFilter *self)
56 {
57 av_freep(&self);
58 }
59
60 void ff_timefilter_reset(TimeFilter *self)
61 {
62 self->count = 0;
63 }
64
65 double ff_timefilter_update(TimeFilter *self, double system_time, double period)
66 {
67 self->count++;
68 if (self->count == 1) {
69 self->cycle_time = system_time;
70 } else {
71 double loop_error;
72 self->cycle_time += self->clock_period * period;
73 loop_error = system_time - self->cycle_time;
74
75 self->cycle_time += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
76 self->clock_period += self->feedback3_factor * loop_error / period;
77 }
78 return self->cycle_time;
79 }