FFmpeg
vf_framestep.c
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1 /*
2  * Copyright (c) 2012 Stefano Sabatini
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file framestep filter, inspired on libmpcodecs/vf_framestep.c by
23  * Daniele Fornighieri <guru AT digitalfantasy it>.
24  */
25 
26 #include "libavutil/opt.h"
27 #include "avfilter.h"
28 #include "internal.h"
29 #include "video.h"
30 
31 typedef struct NullContext {
32  const AVClass *class;
35 
36 #define OFFSET(x) offsetof(FrameStepContext, x)
37 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
38 
39 static const AVOption framestep_options[] = {
40  { "step", "set frame step", OFFSET(frame_step), AV_OPT_TYPE_INT, {.i64=1}, 1, INT_MAX, FLAGS},
41  { NULL },
42 };
43 
44 AVFILTER_DEFINE_CLASS(framestep);
45 
46 static int config_output_props(AVFilterLink *outlink)
47 {
48  AVFilterContext *ctx = outlink->src;
49  FrameStepContext *framestep = ctx->priv;
50  AVFilterLink *inlink = ctx->inputs[0];
51 
52  outlink->frame_rate =
53  av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1});
54 
55  av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n",
56  framestep->frame_step,
57  inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate),
58  outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate));
59  return 0;
60 }
61 
63 {
64  FrameStepContext *framestep = inlink->dst->priv;
65 
66  if (!(inlink->frame_count_out % framestep->frame_step)) {
67  return ff_filter_frame(inlink->dst->outputs[0], ref);
68  } else {
69  av_frame_free(&ref);
70  return 0;
71  }
72 }
73 
74 static const AVFilterPad framestep_inputs[] = {
75  {
76  .name = "default",
77  .type = AVMEDIA_TYPE_VIDEO,
78  .filter_frame = filter_frame,
79  },
80  { NULL }
81 };
82 
83 static const AVFilterPad framestep_outputs[] = {
84  {
85  .name = "default",
86  .type = AVMEDIA_TYPE_VIDEO,
87  .config_props = config_output_props,
88  },
89  { NULL }
90 };
91 
93  .name = "framestep",
94  .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."),
95  .priv_size = sizeof(FrameStepContext),
96  .priv_class = &framestep_class,
97  .inputs = framestep_inputs,
98  .outputs = framestep_outputs,
100 };
static const AVOption framestep_options[]
Definition: vf_framestep.c:39
#define NULL
Definition: coverity.c:32
AVRational av_div_q(AVRational b, AVRational c)
Divide one rational by another.
Definition: rational.c:88
#define FLAGS
Definition: vf_framestep.c:37
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVOption.
Definition: opt.h:246
static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
Definition: vf_framestep.c:62
Main libavfilter public API header.
int num
Numerator.
Definition: rational.h:59
AVFilter ff_vf_framestep
Definition: vf_framestep.c:92
#define AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC
Some filters support a generic "enable" expression option that can be used to enable or disable a fil...
Definition: avfilter.h:125
const char * name
Pad name.
Definition: internal.h:60
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:346
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1080
AVOptions.
static int config_output_props(AVFilterLink *outlink)
Definition: vf_framestep.c:46
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:192
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:54
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:202
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
void * priv
private data for use by the filter
Definition: avfilter.h:353
static const AVFilterPad framestep_inputs[]
Definition: vf_framestep.c:74
static const AVFilterPad framestep_outputs[]
Definition: vf_framestep.c:83
AVFormatContext * ctx
Definition: movenc.c:48
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
#define OFFSET(x)
Definition: vf_framestep.c:36
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
Rational number (pair of numerator and denominator).
Definition: rational.h:58
const char * name
Filter name.
Definition: avfilter.h:148
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
#define flags(name, subs,...)
Definition: cbs_av1.c:561
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
static int ref[MAX_W *MAX_W]
Definition: jpeg2000dwt.c:107
AVFILTER_DEFINE_CLASS(framestep)
int den
Denominator.
Definition: rational.h:60
An instance of a filter.
Definition: avfilter.h:338
internal API functions