1 /*
2 * Copyright (c) 2010 Stefano Sabatini
3 * Copyright (c) 2006 Ivo van Poorten
4 * Copyright (c) 2006 Julian Hall
5 * Copyright (c) 2002-2003 Brian J. Murrell
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License along
20 * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 */
23
24 /**
25 * @file
26 * Search for black frames to detect scene transitions.
27 * Ported from MPlayer libmpcodecs/vf_blackframe.c.
28 */
29
30 #include <stdio.h>
31 #include <inttypes.h>
32
33 #include "libavutil/internal.h"
34 #include "libavutil/opt.h"
35 #include "avfilter.h"
36 #include "formats.h"
37 #include "internal.h"
38 #include "video.h"
39
40 typedef struct BlackFrameContext {
41 const AVClass *class;
42 int bamount; ///< black amount
43 int bthresh; ///< black threshold
44 unsigned int frame; ///< frame number
45 unsigned int nblack; ///< number of black pixels counted so far
46 unsigned int last_keyframe; ///< frame number of the last received key-frame
47 } BlackFrameContext;
48
49 static const enum AVPixelFormat pix_fmts[] = {
50 AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NV12,
51 AV_PIX_FMT_NV21, AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV411P,
52 AV_PIX_FMT_NONE
53 };
54
55 #define SET_META(key, format, value) \
56 snprintf(buf, sizeof(buf), format, value); \
57 av_dict_set(metadata, key, buf, 0)
58
filter_frame(AVFilterLink * inlink,AVFrame * frame)59 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
60 {
61 AVFilterContext *ctx = inlink->dst;
62 BlackFrameContext *s = ctx->priv;
63 int x, i;
64 int pblack = 0;
65 uint8_t *p = frame->data[0];
66 AVDictionary **metadata;
67 char buf[32];
68
69 for (i = 0; i < frame->height; i++) {
70 for (x = 0; x < inlink->w; x++)
71 s->nblack += p[x] < s->bthresh;
72 p += frame->linesize[0];
73 }
74
75 if (frame->key_frame)
76 s->last_keyframe = s->frame;
77
78 pblack = s->nblack * 100 / (inlink->w * inlink->h);
79 if (pblack >= s->bamount) {
80 metadata = &frame->metadata;
81
82 av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pts:%"PRId64" t:%f "
83 "type:%c last_keyframe:%d\n",
84 s->frame, pblack, frame->pts,
85 frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
86 av_get_picture_type_char(frame->pict_type), s->last_keyframe);
87
88 SET_META("lavfi.blackframe.pblack", "%u", pblack);
89 }
90
91 s->frame++;
92 s->nblack = 0;
93 return ff_filter_frame(inlink->dst->outputs[0], frame);
94 }
95
96 #define OFFSET(x) offsetof(BlackFrameContext, x)
97 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
98 static const AVOption blackframe_options[] = {
99 { "amount", "percentage of the pixels that have to be below the threshold "
100 "for the frame to be considered black", OFFSET(bamount), AV_OPT_TYPE_INT, { .i64 = 98 }, 0, 100, FLAGS },
101 { "threshold", "threshold below which a pixel value is considered black",
102 OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
103 { "thresh", "threshold below which a pixel value is considered black",
104 OFFSET(bthresh), AV_OPT_TYPE_INT, { .i64 = 32 }, 0, 255, FLAGS },
105 { NULL }
106 };
107
108 AVFILTER_DEFINE_CLASS(blackframe);
109
110 static const AVFilterPad avfilter_vf_blackframe_inputs[] = {
111 {
112 .name = "default",
113 .type = AVMEDIA_TYPE_VIDEO,
114 .filter_frame = filter_frame,
115 },
116 };
117
118 static const AVFilterPad avfilter_vf_blackframe_outputs[] = {
119 {
120 .name = "default",
121 .type = AVMEDIA_TYPE_VIDEO
122 },
123 };
124
125 const AVFilter ff_vf_blackframe = {
126 .name = "blackframe",
127 .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
128 .priv_size = sizeof(BlackFrameContext),
129 .priv_class = &blackframe_class,
130 .flags = AVFILTER_FLAG_METADATA_ONLY,
131 FILTER_INPUTS(avfilter_vf_blackframe_inputs),
132 FILTER_OUTPUTS(avfilter_vf_blackframe_outputs),
133 FILTER_PIXFMTS_ARRAY(pix_fmts),
134 };
135