cosmetics: drop some pointless parentheses
[ffmpeg.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
26 #include "config.h"
27 #include "timefilter.h"
28 #include "libavutil/mem.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, double feedback2_factor, double feedback3_factor)
41 {
42     TimeFilter *self        = av_mallocz(sizeof(TimeFilter));
43     self->clock_period      = clock_period;
44     self->feedback2_factor  = feedback2_factor;
45     self->feedback3_factor  = feedback3_factor;
46     return self;
47 }
48
49 void ff_timefilter_destroy(TimeFilter *self)
50 {
51     av_freep(&self);
52 }
53
54 void ff_timefilter_reset(TimeFilter *self)
55 {
56     self->count      = 0;
57 }
58
59 double ff_timefilter_update(TimeFilter *self, double system_time, double period)
60 {
61     self->count++;
62     if (self->count==1) {
63         /// init loop
64         self->cycle_time    = system_time;
65     } else {
66         double loop_error;
67         self->cycle_time   += self->clock_period * period;
68         /// calculate loop error
69         loop_error          = system_time - self->cycle_time;
70
71         /// update loop
72         self->cycle_time   += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
73         self->clock_period += self->feedback3_factor * loop_error / period;
74     }
75     return self->cycle_time;
76 }
77
78 #ifdef TEST
79 #include "libavutil/lfg.h"
80 #define LFG_MAX ((1LL << 32) - 1)
81
82 #undef printf
83
84 int main(void)
85 {
86     AVLFG prng;
87     double n0,n1;
88 #define SAMPLES 1000
89     double ideal[SAMPLES];
90     double samples[SAMPLES];
91 #if 1
92     for(n0= 0; n0<40; n0=2*n0+1){
93         for(n1= 0; n1<10; n1=2*n1+1){
94 #else
95     {{
96         n0=7;
97         n1=1;
98 #endif
99             double best_error= 1000000000;
100             double bestpar0=1;
101             double bestpar1=0.001;
102             int better, i;
103
104             av_lfg_init(&prng, 123);
105             for(i=0; i<SAMPLES; i++){
106                 ideal[i]  = 10 + i + n1*i/(1000);
107                 samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2)
108                                            / (LFG_MAX * 10LL);
109             }
110
111             do{
112                 double par0, par1;
113                 better=0;
114                 for(par0= bestpar0*0.8; par0<=bestpar0*1.21; par0+=bestpar0*0.05){
115                     for(par1= bestpar1*0.8; par1<=bestpar1*1.21; par1+=bestpar1*0.05){
116                         double error=0;
117                         TimeFilter *tf= ff_timefilter_new(1, par0, par1);
118                         for(i=0; i<SAMPLES; i++){
119                             double filtered;
120                             filtered=  ff_timefilter_update(tf, samples[i], 1);
121                             error += (filtered - ideal[i]) * (filtered - ideal[i]);
122                         }
123                         ff_timefilter_destroy(tf);
124                         if(error < best_error){
125                             best_error= error;
126                             bestpar0= par0;
127                             bestpar1= par1;
128                             better=1;
129                         }
130                     }
131                 }
132             }while(better);
133 #if 0
134             double lastfil=9;
135             TimeFilter *tf= ff_timefilter_new(1, bestpar0, bestpar1);
136             for(i=0; i<SAMPLES; i++){
137                 double filtered;
138                 filtered=  ff_timefilter_update(tf, samples[i], 1);
139                 printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i], samples[FFMAX(i, 1)] - samples[FFMAX(i-1, 0)], filtered - lastfil);
140                 lastfil= filtered;
141             }
142             ff_timefilter_destroy(tf);
143 #else
144             printf(" [%f %f %9f]", bestpar0, bestpar1, best_error);
145 #endif
146         }
147         printf("\n");
148     }
149     return 0;
150 }
151 #endif