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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 const enum AVPixelFormat yuvj_formats[] = {
69 };
70 
72 {
73  static const enum AVPixelFormat pix_fmts[] = {
81  };
82 
83  AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
84  if (!fmts_list)
85  return AVERROR(ENOMEM);
86  return ff_set_common_formats(ctx, fmts_list);
87 }
88 
89 static int config_input(AVFilterLink *inlink)
90 {
91  AVFilterContext *ctx = inlink->dst;
92  BlackDetectContext *blackdetect = ctx->priv;
93 
94  blackdetect->black_min_duration =
95  blackdetect->black_min_duration_time / av_q2d(inlink->time_base);
96 
97  blackdetect->pixel_black_th_i = ff_fmt_is_in(inlink->format, yuvj_formats) ?
98  // luminance_minimum_value + pixel_black_th * luminance_range_size
99  blackdetect->pixel_black_th * 255 :
100  16 + blackdetect->pixel_black_th * (235 - 16);
101 
102  av_log(blackdetect, AV_LOG_VERBOSE,
103  "black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
104  av_ts2timestr(blackdetect->black_min_duration, &inlink->time_base),
105  blackdetect->pixel_black_th, blackdetect->pixel_black_th_i,
106  blackdetect->picture_black_ratio_th);
107  return 0;
108 }
109 
111 {
112  BlackDetectContext *blackdetect = ctx->priv;
113  AVFilterLink *inlink = ctx->inputs[0];
114 
115  if ((blackdetect->black_end - blackdetect->black_start) >= blackdetect->black_min_duration) {
116  av_log(blackdetect, AV_LOG_INFO,
117  "black_start:%s black_end:%s black_duration:%s\n",
118  av_ts2timestr(blackdetect->black_start, &inlink->time_base),
119  av_ts2timestr(blackdetect->black_end, &inlink->time_base),
120  av_ts2timestr(blackdetect->black_end - blackdetect->black_start, &inlink->time_base));
121  }
122 }
123 
124 static int request_frame(AVFilterLink *outlink)
125 {
126  AVFilterContext *ctx = outlink->src;
127  BlackDetectContext *blackdetect = ctx->priv;
128  AVFilterLink *inlink = ctx->inputs[0];
129  int ret = ff_request_frame(inlink);
130 
131  if (ret == AVERROR_EOF && blackdetect->black_started) {
132  // FIXME: black_end should be set to last_picref_pts + last_picref_duration
133  blackdetect->black_end = blackdetect->last_picref_pts;
134  check_black_end(ctx);
135  }
136  return ret;
137 }
138 
139 // TODO: document metadata
140 static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
141 {
142  AVFilterContext *ctx = inlink->dst;
143  BlackDetectContext *blackdetect = ctx->priv;
144  double picture_black_ratio = 0;
145  const uint8_t *p = picref->data[0];
146  int x, i;
147 
148  for (i = 0; i < inlink->h; i++) {
149  for (x = 0; x < inlink->w; x++)
150  blackdetect->nb_black_pixels += p[x] <= blackdetect->pixel_black_th_i;
151  p += picref->linesize[0];
152  }
153 
154  picture_black_ratio = (double)blackdetect->nb_black_pixels / (inlink->w * inlink->h);
155 
156  av_log(ctx, AV_LOG_DEBUG,
157  "frame:%"PRId64" picture_black_ratio:%f pts:%s t:%s type:%c\n",
158  inlink->frame_count, picture_black_ratio,
159  av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base),
161 
162  if (picture_black_ratio >= blackdetect->picture_black_ratio_th) {
163  if (!blackdetect->black_started) {
164  /* black starts here */
165  blackdetect->black_started = 1;
166  blackdetect->black_start = picref->pts;
167  av_dict_set(avpriv_frame_get_metadatap(picref), "lavfi.black_start",
168  av_ts2timestr(blackdetect->black_start, &inlink->time_base), 0);
169  }
170  } else if (blackdetect->black_started) {
171  /* black ends here */
172  blackdetect->black_started = 0;
173  blackdetect->black_end = picref->pts;
174  check_black_end(ctx);
175  av_dict_set(avpriv_frame_get_metadatap(picref), "lavfi.black_end",
176  av_ts2timestr(blackdetect->black_end, &inlink->time_base), 0);
177  }
178 
179  blackdetect->last_picref_pts = picref->pts;
180  blackdetect->nb_black_pixels = 0;
181  return ff_filter_frame(inlink->dst->outputs[0], picref);
182 }
183 
184 static const AVFilterPad blackdetect_inputs[] = {
185  {
186  .name = "default",
187  .type = AVMEDIA_TYPE_VIDEO,
188  .config_props = config_input,
189  .filter_frame = filter_frame,
190  },
191  { NULL }
192 };
193 
195  {
196  .name = "default",
197  .type = AVMEDIA_TYPE_VIDEO,
198  .request_frame = request_frame,
199  },
200  { NULL }
201 };
202 
204  .name = "blackdetect",
205  .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
206  .priv_size = sizeof(BlackDetectContext),
208  .inputs = blackdetect_inputs,
209  .outputs = blackdetect_outputs,
210  .priv_class = &blackdetect_class,
211 };