vf_blackframe.c
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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 Libav.
8  *
9  * Libav 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  * Libav 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 Libav; if not, write to the Free Software Foundation, Inc.,
21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22  */
23 
30 #include "avfilter.h"
31 
32 typedef struct {
33  unsigned int bamount;
34  unsigned int bthresh;
35  unsigned int frame;
36  unsigned int nblack;
38 
40 {
41  static const enum PixelFormat pix_fmts[] = {
45  };
46 
48  return 0;
49 }
50 
51 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
52 {
53  BlackFrameContext *blackframe = ctx->priv;
54 
55  blackframe->bamount = 98;
56  blackframe->bthresh = 32;
57  blackframe->nblack = 0;
58  blackframe->frame = 0;
59 
60  if (args)
61  sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
62 
63  av_log(ctx, AV_LOG_INFO, "bamount:%u bthresh:%u\n",
64  blackframe->bamount, blackframe->bthresh);
65 
66  if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
67  av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
68  return AVERROR(EINVAL);
69  }
70 
71  return 0;
72 }
73 
74 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
75 {
76  AVFilterContext *ctx = inlink->dst;
77  BlackFrameContext *blackframe = ctx->priv;
78  AVFilterBufferRef *picref = inlink->cur_buf;
79  int x, i;
80  uint8_t *p = picref->data[0] + y * picref->linesize[0];
81 
82  for (i = 0; i < h; i++) {
83  for (x = 0; x < inlink->w; x++)
84  blackframe->nblack += p[x] < blackframe->bthresh;
85  p += picref->linesize[0];
86  }
87 
88  avfilter_draw_slice(ctx->outputs[0], y, h, slice_dir);
89 }
90 
91 static void end_frame(AVFilterLink *inlink)
92 {
93  AVFilterContext *ctx = inlink->dst;
94  BlackFrameContext *blackframe = ctx->priv;
95  AVFilterBufferRef *picref = inlink->cur_buf;
96  int pblack = 0;
97 
98  pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
99  if (pblack >= blackframe->bamount)
100  av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pos:%"PRId64" pts:%"PRId64" t:%f\n",
101  blackframe->frame, pblack, picref->pos, picref->pts,
102  picref->pts == AV_NOPTS_VALUE ? -1 : picref->pts * av_q2d(inlink->time_base));
103 
104  blackframe->frame++;
105  blackframe->nblack = 0;
106  avfilter_end_frame(inlink->dst->outputs[0]);
107 }
108 
110  .name = "blackframe",
111  .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
112 
113  .priv_size = sizeof(BlackFrameContext),
114  .init = init,
115 
117 
118  .inputs = (AVFilterPad[]) {{ .name = "default",
119  .type = AVMEDIA_TYPE_VIDEO,
120  .draw_slice = draw_slice,
121  .get_video_buffer = avfilter_null_get_video_buffer,
122  .start_frame = avfilter_null_start_frame,
123  .end_frame = end_frame, },
124  { .name = NULL}},
125 
126  .outputs = (AVFilterPad[]) {{ .name = "default",
127  .type = AVMEDIA_TYPE_VIDEO },
128  { .name = NULL}},
129 };