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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 
62 static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
63 {
64  FrameStepContext *framestep = inlink->dst->priv;
65 
66  if (!(inlink->frame_count % 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:184
AVOption.
Definition: opt.h:245
static int filter_frame(AVFilterLink *inlink, AVFrame *ref)
Definition: vf_framestep.c:62
Main libavfilter public API header.
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:59
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:315
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1189
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:53
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:153
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
void * priv
private data for use by the filter
Definition: avfilter.h:322
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_afftfilt.c:386
#define OFFSET(x)
Definition: vf_framestep.c:36
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:376
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:319
static int flags
Definition: cpu.c:47
static int ref[MAX_W *MAX_W]
Definition: jpeg2000dwt.c:107
AVFILTER_DEFINE_CLASS(framestep)
An instance of a filter.
Definition: avfilter.h:307
internal API functions