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vf_blackdetect.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
23  * Video black detector, loosely based on blackframe with extended
24  * syntax and features
25  */
26 
27 #include <float.h>
28 #include "libavutil/opt.h"
29 #include "libavutil/timestamp.h"
30 #include "avfilter.h"
31 #include "internal.h"
32 
33 typedef struct {
34  const AVClass *class;
35  double black_min_duration_time; ///< minimum duration of detected black, in seconds
36  int64_t black_min_duration; ///< minimum duration of detected black, expressed in timebase units
37  int64_t black_start; ///< pts start time of the first black picture
38  int64_t black_end; ///< pts end time of the last black picture
39  int64_t last_picref_pts; ///< pts of the last input picture
41 
44  unsigned int pixel_black_th_i;
45 
46  unsigned int nb_black_pixels; ///< number of black pixels counted so far
48 
49 #define OFFSET(x) offsetof(BlackDetectContext, x)
50 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
51 
52 static const AVOption blackdetect_options[] = {
53  { "d", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX, FLAGS },
54  { "black_min_duration", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX, FLAGS },
55  { "picture_black_ratio_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1, FLAGS },
56  { "pic_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1, FLAGS },
57  { "pixel_black_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1, FLAGS },
58  { "pix_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1, FLAGS },
59  { NULL },
60 };
61 
62 AVFILTER_DEFINE_CLASS(blackdetect);
63 
64 #define YUVJ_FORMATS \
65  AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P
66 
67 static enum AVPixelFormat yuvj_formats[] = {
69 };
70 
72 {
73  static const enum AVPixelFormat pix_fmts[] = {
81  };
82 
84  return 0;
85 }
86 
87 static int config_input(AVFilterLink *inlink)
88 {
89  AVFilterContext *ctx = inlink->dst;
90  BlackDetectContext *blackdetect = ctx->priv;
91 
92  blackdetect->black_min_duration =
93  blackdetect->black_min_duration_time / av_q2d(inlink->time_base);
94 
95  blackdetect->pixel_black_th_i = ff_fmt_is_in(inlink->format, yuvj_formats) ?
96  // luminance_minimum_value + pixel_black_th * luminance_range_size
97  blackdetect->pixel_black_th * 255 :
98  16 + blackdetect->pixel_black_th * (235 - 16);
99 
100  av_log(blackdetect, AV_LOG_VERBOSE,
101  "black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
102  av_ts2timestr(blackdetect->black_min_duration, &inlink->time_base),
103  blackdetect->pixel_black_th, blackdetect->pixel_black_th_i,
104  blackdetect->picture_black_ratio_th);
105  return 0;
106 }
107 
109 {
110  BlackDetectContext *blackdetect = ctx->priv;
111  AVFilterLink *inlink = ctx->inputs[0];
112 
113  if ((blackdetect->black_end - blackdetect->black_start) >= blackdetect->black_min_duration) {
114  av_log(blackdetect, AV_LOG_INFO,
115  "black_start:%s black_end:%s black_duration:%s\n",
116  av_ts2timestr(blackdetect->black_start, &inlink->time_base),
117  av_ts2timestr(blackdetect->black_end, &inlink->time_base),
118  av_ts2timestr(blackdetect->black_end - blackdetect->black_start, &inlink->time_base));
119  }
120 }
121 
122 static int request_frame(AVFilterLink *outlink)
123 {
124  AVFilterContext *ctx = outlink->src;
125  BlackDetectContext *blackdetect = ctx->priv;
126  AVFilterLink *inlink = ctx->inputs[0];
127  int ret = ff_request_frame(inlink);
128 
129  if (ret == AVERROR_EOF && blackdetect->black_started) {
130  // FIXME: black_end should be set to last_picref_pts + last_picref_duration
131  blackdetect->black_end = blackdetect->last_picref_pts;
132  check_black_end(ctx);
133  }
134  return ret;
135 }
136 
137 static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
138 {
139  AVFilterContext *ctx = inlink->dst;
140  BlackDetectContext *blackdetect = ctx->priv;
141  double picture_black_ratio = 0;
142  const uint8_t *p = picref->data[0];
143  int x, i;
144 
145  for (i = 0; i < inlink->h; i++) {
146  for (x = 0; x < inlink->w; x++)
147  blackdetect->nb_black_pixels += p[x] <= blackdetect->pixel_black_th_i;
148  p += picref->linesize[0];
149  }
150 
151  picture_black_ratio = (double)blackdetect->nb_black_pixels / (inlink->w * inlink->h);
152 
153  av_log(ctx, AV_LOG_DEBUG,
154  "frame:%"PRId64" picture_black_ratio:%f pts:%s t:%s type:%c\n",
155  inlink->frame_count, picture_black_ratio,
156  av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base),
158 
159  if (picture_black_ratio >= blackdetect->picture_black_ratio_th) {
160  if (!blackdetect->black_started) {
161  /* black starts here */
162  blackdetect->black_started = 1;
163  blackdetect->black_start = picref->pts;
164  }
165  } else if (blackdetect->black_started) {
166  /* black ends here */
167  blackdetect->black_started = 0;
168  blackdetect->black_end = picref->pts;
169  check_black_end(ctx);
170  }
171 
172  blackdetect->last_picref_pts = picref->pts;
173  blackdetect->nb_black_pixels = 0;
174  return ff_filter_frame(inlink->dst->outputs[0], picref);
175 }
176 
177 static const AVFilterPad blackdetect_inputs[] = {
178  {
179  .name = "default",
180  .type = AVMEDIA_TYPE_VIDEO,
181  .config_props = config_input,
182  .get_video_buffer = ff_null_get_video_buffer,
183  .filter_frame = filter_frame,
184  },
185  { NULL }
186 };
187 
189  {
190  .name = "default",
191  .type = AVMEDIA_TYPE_VIDEO,
192  .request_frame = request_frame,
193  },
194  { NULL }
195 };
196 
198  .name = "blackdetect",
199  .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
200  .priv_size = sizeof(BlackDetectContext),
202  .inputs = blackdetect_inputs,
203  .outputs = blackdetect_outputs,
204  .priv_class = &blackdetect_class,
205 };