FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
vf_blackframe.c
Go to the documentation of this file.
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 "avfilter.h"
35 #include "internal.h"
36 #include "formats.h"
37 #include "internal.h"
38 #include "video.h"
39 
40 typedef struct {
41  unsigned int bamount; ///< black amount
42  unsigned int bthresh; ///< black threshold
43  unsigned int frame; ///< frame number
44  unsigned int nblack; ///< number of black pixels counted so far
45  unsigned int last_keyframe; ///< frame number of the last received key-frame
47 
49 {
50  static const enum AVPixelFormat pix_fmts[] = {
54  };
55 
57  return 0;
58 }
59 
60 static av_cold int init(AVFilterContext *ctx, const char *args)
61 {
62  BlackFrameContext *blackframe = ctx->priv;
63 
64  blackframe->bamount = 98;
65  blackframe->bthresh = 32;
66  blackframe->nblack = 0;
67  blackframe->frame = 0;
68  blackframe->last_keyframe = 0;
69 
70  if (args)
71  sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
72 
73  av_log(ctx, AV_LOG_VERBOSE, "bamount:%u bthresh:%u\n",
74  blackframe->bamount, blackframe->bthresh);
75 
76  if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
77  av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
78  return AVERROR(EINVAL);
79  }
80 
81  return 0;
82 }
83 
85 {
86  AVFilterContext *ctx = inlink->dst;
87  BlackFrameContext *blackframe = ctx->priv;
88  int x, i;
89  int pblack = 0;
90  uint8_t *p = frame->data[0];
91 
92  for (i = 0; i < frame->video->h; i++) {
93  for (x = 0; x < inlink->w; x++)
94  blackframe->nblack += p[x] < blackframe->bthresh;
95  p += frame->linesize[0];
96  }
97 
98  if (frame->video->key_frame)
99  blackframe->last_keyframe = blackframe->frame;
100 
101  pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
102  if (pblack >= blackframe->bamount)
103  av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pos:%"PRId64" pts:%"PRId64" t:%f "
104  "type:%c last_keyframe:%d\n",
105  blackframe->frame, pblack, frame->pos, frame->pts,
106  frame->pts == AV_NOPTS_VALUE ? -1 : frame->pts * av_q2d(inlink->time_base),
107  av_get_picture_type_char(frame->video->pict_type), blackframe->last_keyframe);
108 
109  blackframe->frame++;
110  blackframe->nblack = 0;
111  return ff_filter_frame(inlink->dst->outputs[0], frame);
112 }
113 
115  {
116  .name = "default",
117  .type = AVMEDIA_TYPE_VIDEO,
118  .get_video_buffer = ff_null_get_video_buffer,
119  .filter_frame = filter_frame,
120  },
121  { NULL }
122 };
123 
125  {
126  .name = "default",
127  .type = AVMEDIA_TYPE_VIDEO
128  },
129  { NULL }
130 };
131 
133  .name = "blackframe",
134  .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
135 
136  .priv_size = sizeof(BlackFrameContext),
137  .init = init,
138 
140 
141  .inputs = avfilter_vf_blackframe_inputs,
142 
143  .outputs = avfilter_vf_blackframe_outputs,
144 };