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vf_blackframe.c
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1 /*
2  * Copyright (c) 2010 Stefano Sabatini
3  * Copyright (c) 2006 Ivo van Poorten
4  * Copyright (c) 2006 Julian Hall
5  * Copyright (c) 2002-2003 Brian J. Murrell
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License along
20  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22  */
23 
24 /**
25  * @file
26  * Search for black frames to detect scene transitions.
27  * Ported from MPlayer libmpcodecs/vf_blackframe.c.
28  */
29 
30 #include <stdio.h>
31 #include <inttypes.h>
32 
33 #include "libavutil/internal.h"
34 #include "libavutil/opt.h"
35 #include "avfilter.h"
36 #include "formats.h"
37 #include "internal.h"
38 #include "video.h"
39 
40 typedef struct {
41  const AVClass *class;
42  int bamount; ///< black amount
43  int bthresh; ///< black threshold
44  unsigned int frame; ///< frame number
45  unsigned int nblack; ///< number of black pixels counted so far
46  unsigned int last_keyframe; ///< frame number of the last received key-frame
48 
50 {
51  static const enum AVPixelFormat pix_fmts[] = {
55  };
56 
58  return 0;
59 }
60 
61 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
62 {
63  AVFilterContext *ctx = inlink->dst;
64  BlackFrameContext *s = ctx->priv;
65  int x, i;
66  int pblack = 0;
67  uint8_t *p = frame->data[0];
68 
69  for (i = 0; i < frame->height; i++) {
70  for (x = 0; x < inlink->w; x++)
71  s->nblack += p[x] < s->bthresh;
72  p += frame->linesize[0];
73  }
74 
75  if (frame->key_frame)
76  s->last_keyframe = s->frame;
77 
78  pblack = s->nblack * 100 / (inlink->w * inlink->h);
79  if (pblack >= s->bamount)
80  av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
81  "type:%c last_keyframe:%d\n",
82  s->frame, pblack, frame->pts,
83  frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
85 
86  s->frame++;
87  s->nblack = 0;
88  return ff_filter_frame(inlink->dst->outputs[0], frame);
89 }
90 
91 #define OFFSET(x) offsetof(BlackFrameContext, x)
92 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
93 static const AVOption blackframe_options[] = {
94  { "amount", "Percentage of the pixels that have to be below the threshold "
95  "for the frame to be considered black.", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100, FLAGS },
96  { "threshold", "threshold below which a pixel value is considered black",
97  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
98  { "thresh", "threshold below which a pixel value is considered black",
99  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
100  { NULL }
101 };
102 
103 AVFILTER_DEFINE_CLASS(blackframe);
104 
106  {
107  .name = "default",
108  .type = AVMEDIA_TYPE_VIDEO,
109  .filter_frame = filter_frame,
110  },
111  { NULL }
112 };
113 
115  {
116  .name = "default",
117  .type = AVMEDIA_TYPE_VIDEO
118  },
119  { NULL }
120 };
121 
123  .name = "blackframe",
124  .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
125  .priv_size = sizeof(BlackFrameContext),
126  .priv_class = &blackframe_class,
128  .inputs = avfilter_vf_blackframe_inputs,
129  .outputs = avfilter_vf_blackframe_outputs,
130 };