2 * Copyright (c) 2012 Stefano Sabatini
4 * This file is part of FFmpeg.
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.
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.
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
23 * Video black detector, loosely based on blackframe with extended
28 #include "libavutil/opt.h"
29 #include "libavutil/timestamp.h"
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
41 double picture_black_ratio_th;
42 double pixel_black_th;
43 unsigned int pixel_black_th_i;
45 unsigned int frame_count; ///< frame number
46 unsigned int nb_black_pixels; ///< number of black pixels counted so far
49 #define OFFSET(x) offsetof(BlackDetectContext, x)
50 static const AVOption blackdetect_options[] = {
51 { "d", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX},
52 { "black_min_duration", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX},
53 { "picture_black_ratio_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1},
54 { "pic_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1},
55 { "pixel_black_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1},
56 { "pix_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1},
60 static const char *blackdetect_get_name(void *ctx)
65 static const AVClass blackdetect_class = {
66 .class_name = "BlackDetectContext",
67 .item_name = blackdetect_get_name,
68 .option = blackdetect_options,
71 #define YUVJ_FORMATS \
72 PIX_FMT_YUVJ420P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ444P, PIX_FMT_YUVJ440P
74 static enum PixelFormat yuvj_formats[] = {
75 YUVJ_FORMATS, PIX_FMT_NONE
78 static int query_formats(AVFilterContext *ctx)
80 static const enum PixelFormat pix_fmts[] = {
81 PIX_FMT_YUV410P, PIX_FMT_YUV420P, PIX_FMT_GRAY8, PIX_FMT_NV12,
82 PIX_FMT_NV21, PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV411P,
87 avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
91 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
94 BlackDetectContext *blackdetect = ctx->priv;
96 blackdetect->class = &blackdetect_class;
97 av_opt_set_defaults(blackdetect);
99 if ((ret = av_set_options_string(blackdetect, args, "=", ":")) < 0) {
100 av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
107 static int config_input(AVFilterLink *inlink)
109 AVFilterContext *ctx = inlink->dst;
110 BlackDetectContext *blackdetect = ctx->priv;
112 blackdetect->black_min_duration =
113 blackdetect->black_min_duration_time / av_q2d(inlink->time_base);
115 blackdetect->pixel_black_th_i = ff_fmt_is_in(inlink->format, yuvj_formats) ?
116 // luminance_minimum_value + pixel_black_th * luminance_range_size
117 blackdetect->pixel_black_th * 255 :
118 16 + blackdetect->pixel_black_th * (235 - 16);
120 av_log(blackdetect, AV_LOG_INFO,
121 "black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
122 av_ts2timestr(blackdetect->black_min_duration, &inlink->time_base),
123 blackdetect->pixel_black_th, blackdetect->pixel_black_th_i,
124 blackdetect->picture_black_ratio_th);
128 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
130 AVFilterContext *ctx = inlink->dst;
131 BlackDetectContext *blackdetect = ctx->priv;
132 AVFilterBufferRef *picref = inlink->cur_buf;
134 const uint8_t *p = picref->data[0] + y * picref->linesize[0];
136 for (i = 0; i < h; i++) {
137 for (x = 0; x < inlink->w; x++)
138 blackdetect->nb_black_pixels += p[x] <= blackdetect->pixel_black_th_i;
139 p += picref->linesize[0];
142 avfilter_draw_slice(ctx->outputs[0], y, h, slice_dir);
145 static void end_frame(AVFilterLink *inlink)
147 AVFilterContext *ctx = inlink->dst;
148 BlackDetectContext *blackdetect = ctx->priv;
149 AVFilterBufferRef *picref = inlink->cur_buf;
150 double picture_black_ratio = 0;
152 picture_black_ratio = (double)blackdetect->nb_black_pixels / (inlink->w * inlink->h);
154 av_log(ctx, AV_LOG_DEBUG,
155 "frame:%u picture_black_ratio:%f pos:%"PRId64" pts:%s t:%s type:%c\n",
156 blackdetect->frame_count, picture_black_ratio,
157 picref->pos, av_ts2str(picref->pts),
158 av_ts2timestr(blackdetect->black_start, &inlink->time_base),
159 av_get_picture_type_char(picref->video->pict_type));
161 if (picture_black_ratio >= blackdetect->picture_black_ratio_th) {
162 if (!blackdetect->black_started) {
163 /* black starts here */
164 blackdetect->black_started = 1;
165 blackdetect->black_start = picref->pts;
167 } else if (blackdetect->black_started) {
168 /* black ends here */
169 blackdetect->black_started = 0;
170 blackdetect->black_end = picref->pts;
172 if ((blackdetect->black_end - blackdetect->black_start) >= blackdetect->black_min_duration) {
173 av_log(blackdetect, AV_LOG_INFO,
174 "black_start:%s black_end:%s black_duration:%s\n",
175 av_ts2timestr(blackdetect->black_start, &inlink->time_base),
176 av_ts2timestr(blackdetect->black_end, &inlink->time_base),
177 av_ts2timestr(blackdetect->black_end - blackdetect->black_start, &inlink->time_base));
181 blackdetect->frame_count++;
182 blackdetect->nb_black_pixels = 0;
183 avfilter_unref_buffer(picref);
184 avfilter_end_frame(inlink->dst->outputs[0]);
187 AVFilter avfilter_vf_blackdetect = {
188 .name = "blackdetect",
189 .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
190 .priv_size = sizeof(BlackDetectContext),
192 .query_formats = query_formats,
194 .inputs = (const AVFilterPad[]) {
196 .type = AVMEDIA_TYPE_VIDEO,
197 .config_props = config_input,
198 .draw_slice = draw_slice,
199 .get_video_buffer = avfilter_null_get_video_buffer,
200 .start_frame = ff_null_start_frame_keep_ref,
201 .end_frame = end_frame, },
205 .outputs = (const AVFilterPad[]) {
207 .type = AVMEDIA_TYPE_VIDEO },