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path: root/libavfilter/vf_blackdetect.c (plain)
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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
33typedef 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
52static 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
62AVFILTER_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
67static const enum AVPixelFormat yuvj_formats[] = {
68 YUVJ_FORMATS, AV_PIX_FMT_NONE
69};
70
71static 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 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
89static 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
110static void check_black_end(AVFilterContext *ctx)
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
124static 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
140static 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_out, picture_black_ratio,
159 av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base),
160 av_get_picture_type_char(picref->pict_type));
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
184static 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
194static const AVFilterPad blackdetect_outputs[] = {
195 {
196 .name = "default",
197 .type = AVMEDIA_TYPE_VIDEO,
198 .request_frame = request_frame,
199 },
200 { NULL }
201};
202
203AVFilter ff_vf_blackdetect = {
204 .name = "blackdetect",
205 .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
206 .priv_size = sizeof(BlackDetectContext),
207 .query_formats = query_formats,
208 .inputs = blackdetect_inputs,
209 .outputs = blackdetect_outputs,
210 .priv_class = &blackdetect_class,
211};
212
generated by cgit at 2024-05-17 02:13:14 (GMT)