FFmpeg: libavfilter/vf_blackdetect.c Source File

FFmpeg
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
40   int black_started;
41 
42   double picture_black_ratio_th;
43   double pixel_black_th;
44   unsigned int pixel_black_th_i;
45 
46   unsigned int nb_black_pixels; ///< number of black pixels counted so far
47 } BlackDetectContext;
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[] = {
68  YUVJ_FORMATS, AV_PIX_FMT_NONE
69 };
70 
71  static int query_formats(AVFilterContext *ctx)
72 {
73  static const enum AVPixelFormat pix_fmts[] = {
74  AV_PIX_FMT_GRAY8,
75  AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
76  AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
77  AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
78  AV_PIX_FMT_NV12, AV_PIX_FMT_NV21,
79  YUVJ_FORMATS,
80  AV_PIX_FMT_NONE
81  };
82 
83  ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
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 
108  static void check_black_end(AVFilterContext *ctx)
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 // TODO: document metadata
138  static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
139 {
140  AVFilterContext *ctx = inlink->dst;
141  BlackDetectContext *blackdetect = ctx->priv;
142  double picture_black_ratio = 0;
143  const uint8_t *p = picref->data[0];
144  int x, i;
145 
146  for (i = 0; i < inlink->h; i++) {
147  for (x = 0; x < inlink->w; x++)
148  blackdetect->nb_black_pixels += p[x] <= blackdetect->pixel_black_th_i;
149  p += picref->linesize[0];
150  }
151 
152  picture_black_ratio = (double)blackdetect->nb_black_pixels / (inlink->w * inlink->h);
153 
154  av_log(ctx, AV_LOG_DEBUG,
155  "frame:%"PRId64" picture_black_ratio:%f pts:%s t:%s type:%c\n",
156  inlink->frame_count, picture_black_ratio,
157  av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base),
158  av_get_picture_type_char(picref->pict_type));
159 
160  if (picture_black_ratio >= blackdetect->picture_black_ratio_th) {
161  if (!blackdetect->black_started) {
162  /* black starts here */
163  blackdetect->black_started = 1;
164  blackdetect->black_start = picref->pts;
165  av_dict_set(avpriv_frame_get_metadatap(picref), "lavfi.black_start",
166  av_ts2timestr(blackdetect->black_start, &inlink->time_base), 0);
167  }
168  } else if (blackdetect->black_started) {
169  /* black ends here */
170  blackdetect->black_started = 0;
171  blackdetect->black_end = picref->pts;
172  check_black_end(ctx);
173  av_dict_set(avpriv_frame_get_metadatap(picref), "lavfi.black_end",
174  av_ts2timestr(blackdetect->black_end, &inlink->time_base), 0);
175  }
176 
177  blackdetect->last_picref_pts = picref->pts;
178  blackdetect->nb_black_pixels = 0;
179  return ff_filter_frame(inlink->dst->outputs[0], picref);
180 }
181 
182  static const AVFilterPad blackdetect_inputs[] = {
183  {
184  .name = "default",
185  .type = AVMEDIA_TYPE_VIDEO,
186  .config_props = config_input,
187  .filter_frame = filter_frame,
188  },
189  { NULL }
190 };
191 
192  static const AVFilterPad blackdetect_outputs[] = {
193  {
194  .name = "default",
195  .type = AVMEDIA_TYPE_VIDEO,
196  .request_frame = request_frame,
197  },
198  { NULL }
199 };
200 
201  AVFilter ff_vf_blackdetect = {
202  .name = "blackdetect",
203  .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
204  .priv_size = sizeof(BlackDetectContext),
205  .query_formats = query_formats,
206  .inputs = blackdetect_inputs,
207  .outputs = blackdetect_outputs,
208  .priv_class = &blackdetect_class,
209 };
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