FFmpeg  4.3
timefilter.c
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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 FFmpeg.
9  *
10  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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;
36  double clock_period;
37  int count;
38 };
39 
40 /* 1 - exp(-x) using a 3-order power series */
41 static double qexpneg(double x)
42 {
43  return 1 - 1 / (1 + x * (1 + x / 2 * (1 + x / 3)));
44 }
45 
46 TimeFilter *ff_timefilter_new(double time_base,
47  double period,
48  double bandwidth)
49 {
50  TimeFilter *self = av_mallocz(sizeof(TimeFilter));
51  double o = 2 * M_PI * bandwidth * period * time_base;
52 
53  if (!self)
54  return NULL;
55 
56  self->clock_period = time_base;
57  self->feedback2_factor = qexpneg(M_SQRT2 * o);
58  self->feedback3_factor = qexpneg(o * o) / period;
59  return self;
60 }
61 
63 {
64  av_freep(&self);
65 }
66 
68 {
69  self->count = 0;
70 }
71 
72 double ff_timefilter_update(TimeFilter *self, double system_time, double period)
73 {
74  self->count++;
75  if (self->count == 1) {
76  self->cycle_time = system_time;
77  } else {
78  double loop_error;
79  self->cycle_time += self->clock_period * period;
80  loop_error = system_time - self->cycle_time;
81 
82  self->cycle_time += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error;
83  self->clock_period += self->feedback3_factor * loop_error;
84  }
85  return self->cycle_time;
86 }
87 
88 double ff_timefilter_eval(TimeFilter *self, double delta)
89 {
90  return self->cycle_time + self->clock_period * delta;
91 }
TimeFilter
Opaque type representing a time filter state.
Definition: timefilter.c:30
TimeFilter::cycle_time
double cycle_time
Definition: timefilter.c:33
ff_timefilter_eval
double ff_timefilter_eval(TimeFilter *self, double delta)
Evaluate the filter at a specified time.
Definition: timefilter.c:88
x
FFmpeg Automated Testing Environment ************************************Introduction Using FATE from your FFmpeg source directory Submitting the results to the FFmpeg result aggregation server Uploading new samples to the fate suite FATE makefile targets and variables Makefile targets Makefile variables Examples Introduction **************FATE is an extended regression suite on the client side and a means for results aggregation and presentation on the server side The first part of this document explains how you can use FATE from your FFmpeg source directory to test your ffmpeg binary The second part describes how you can run FATE to submit the results to FFmpeg’s FATE server In any way you can have a look at the publicly viewable FATE results by visiting this as it can be seen if some test on some platform broke with their recent contribution This usually happens on the platforms the developers could not test on The second part of this document describes how you can run FATE to submit your results to FFmpeg’s FATE server If you want to submit your results be sure to check that your combination of OS and compiler is not already listed on the above mentioned website In the third part you can find a comprehensive listing of FATE makefile targets and variables Using FATE from your FFmpeg source directory **********************************************If you want to run FATE on your machine you need to have the samples in place You can get the samples via the build target fate rsync Use this command from the top level source this will cause FATE to fail NOTE To use a custom wrapper to run the pass ‘ target exec’ to ‘configure’ or set the TARGET_EXEC Make variable Submitting the results to the FFmpeg result aggregation server ****************************************************************To submit your results to the server you should run fate through the shell script ‘tests fate sh’ from the FFmpeg sources This script needs to be invoked with a configuration file as its first argument tests fate sh path to fate_config A configuration file template with comments describing the individual configuration variables can be found at ‘doc fate_config sh template’ Create a configuration that suits your based on the configuration template The ‘slot’ configuration variable can be any string that is not yet but it is suggested that you name it adhering to the following pattern ‘ARCH OS COMPILER COMPILER VERSION’ The configuration file itself will be sourced in a shell therefore all shell features may be used This enables you to setup the environment as you need it for your build For your first test runs the ‘fate_recv’ variable should be empty or commented out This will run everything as normal except that it will omit the submission of the results to the server The following files should be present in $workdir as specified in the configuration it may help to try out the ‘ssh’ command with one or more ‘ v’ options You should get detailed output concerning your SSH configuration and the authentication process The only thing left is to automate the execution of the fate sh script and the synchronisation of the samples directory Uploading new samples to the fate suite *****************************************If you need a sample uploaded send a mail to samples request This is for developers who have an account on the fate suite server If you upload new please make sure they are as small as space on each network bandwidth and so on benefit from smaller test cases Also keep in mind older checkouts use existing sample that means in practice generally do not remove or overwrite files as it likely would break older checkouts or releases Also all needed samples for a commit should be ideally before the push If you need an account for frequently uploading samples or you wish to help others by doing that send a mail to ffmpeg devel rsync vauL Duo x
Definition: fate.txt:150
ff_timefilter_new
TimeFilter * ff_timefilter_new(double time_base, double period, double bandwidth)
Create a new Delay Locked Loop time filter.
Definition: timefilter.c:46
TimeFilter::count
int count
Definition: timefilter.c:37
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:239
TimeFilter::clock_period
double clock_period
Definition: timefilter.c:36
NULL
#define NULL
Definition: coverity.c:32
timefilter.h
period
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option keep it simple and lowercase description are in without period
Definition: writing_filters.txt:89
FFMAX
#define FFMAX(a, b)
Definition: common.h:94
ff_timefilter_reset
void ff_timefilter_reset(TimeFilter *self)
Reset the filter.
Definition: timefilter.c:67
M_PI
#define M_PI
Definition: mathematics.h:52
TimeFilter::feedback3_factor
double feedback3_factor
Definition: timefilter.c:35
ff_timefilter_destroy
void ff_timefilter_destroy(TimeFilter *self)
Free all resources associated with the filter.
Definition: timefilter.c:62
common.h
delta
float delta
Definition: vorbis_enc_data.h:457
ff_timefilter_update
double ff_timefilter_update(TimeFilter *self, double system_time, double period)
Update the filter.
Definition: timefilter.c:72
qexpneg
static double qexpneg(double x)
Definition: timefilter.c:41
mem.h
M_SQRT2
#define M_SQRT2
Definition: mathematics.h:61
TimeFilter::feedback2_factor
double feedback2_factor
Definition: timefilter.c:34
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35