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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 BlackFrameContext {
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 #define SET_META(key, format, value) \
62  snprintf(buf, sizeof(buf), format, value); \
63  av_dict_set(metadata, key, buf, 0)
64 
65 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
66 {
67  AVFilterContext *ctx = inlink->dst;
68  BlackFrameContext *s = ctx->priv;
69  int x, i;
70  int pblack = 0;
71  uint8_t *p = frame->data[0];
72  AVDictionary **metadata;
73  char buf[32];
74 
75  for (i = 0; i < frame->height; i++) {
76  for (x = 0; x < inlink->w; x++)
77  s->nblack += p[x] < s->bthresh;
78  p += frame->linesize[0];
79  }
80 
81  if (frame->key_frame)
82  s->last_keyframe = s->frame;
83 
84  pblack = s->nblack * 100 / (inlink->w * inlink->h);
85  if (pblack >= s->bamount) {
86  metadata = avpriv_frame_get_metadatap(frame);
87 
88  av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
89  "type:%c last_keyframe:%d\n",
90  s->frame, pblack, frame->pts,
91  frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
93 
94  SET_META("lavfi.blackframe.pblack", "%u", pblack);
95  }
96 
97  s->frame++;
98  s->nblack = 0;
99  return ff_filter_frame(inlink->dst->outputs[0], frame);
100 }
101 
102 #define OFFSET(x) offsetof(BlackFrameContext, x)
103 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
104 static const AVOption blackframe_options[] = {
105  { "amount", "Percentage of the pixels that have to be below the threshold "
106  "for the frame to be considered black.", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100, FLAGS },
107  { "threshold", "threshold below which a pixel value is considered black",
108  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
109  { "thresh", "threshold below which a pixel value is considered black",
110  OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
111  { NULL }
112 };
113 
114 AVFILTER_DEFINE_CLASS(blackframe);
115 
117  {
118  .name = "default",
119  .type = AVMEDIA_TYPE_VIDEO,
120  .filter_frame = filter_frame,
121  },
122  { NULL }
123 };
124 
126  {
127  .name = "default",
128  .type = AVMEDIA_TYPE_VIDEO
129  },
130  { NULL }
131 };
132 
134  .name = "blackframe",
135  .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
136  .priv_size = sizeof(BlackFrameContext),
137  .priv_class = &blackframe_class,
139  .inputs = avfilter_vf_blackframe_inputs,
140  .outputs = avfilter_vf_blackframe_outputs,
141 };