vf_cropdetect.c
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1 /*
2  * Copyright (c) 2002 A'rpi
3  * This file is part of Libav.
4  *
5  * Libav is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * Libav is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License along
16  * with Libav; if not, write to the Free Software Foundation, Inc.,
17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18  */
19 
26 #include "libavutil/imgutils.h"
27 #include "avfilter.h"
28 
29 typedef struct {
30  int x1, y1, x2, y2;
31  int limit;
32  int round;
34  int frame_nb;
35  int max_pixsteps[4];
37 
39 {
40  static const enum PixelFormat pix_fmts[] = {
47  };
48 
50  return 0;
51 }
52 
53 static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
54 {
55  int total = 0;
56  int div = len;
57 
58  switch (bpp) {
59  case 1:
60  while (--len >= 0) {
61  total += src[0];
62  src += stride;
63  }
64  break;
65  case 3:
66  case 4:
67  while (--len >= 0) {
68  total += src[0] + src[1] + src[2];
69  src += stride;
70  }
71  div *= 3;
72  break;
73  }
74  total /= div;
75 
76  av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
77  return total;
78 }
79 
80 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
81 {
82  CropDetectContext *cd = ctx->priv;
83 
84  cd->limit = 24;
85  cd->round = 0;
86  cd->reset_count = 0;
87  cd->frame_nb = -2;
88 
89  if (args)
90  sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
91 
92  av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
93  cd->limit, cd->round, cd->reset_count);
94 
95  return 0;
96 }
97 
98 static int config_input(AVFilterLink *inlink)
99 {
100  AVFilterContext *ctx = inlink->dst;
101  CropDetectContext *cd = ctx->priv;
102 
104  &av_pix_fmt_descriptors[inlink->format]);
105 
106  cd->x1 = inlink->w - 1;
107  cd->y1 = inlink->h - 1;
108  cd->x2 = 0;
109  cd->y2 = 0;
110 
111  return 0;
112 }
113 
114 static void end_frame(AVFilterLink *inlink)
115 {
116  AVFilterContext *ctx = inlink->dst;
117  CropDetectContext *cd = ctx->priv;
118  AVFilterBufferRef *picref = inlink->cur_buf;
119  int bpp = cd->max_pixsteps[0];
120  int w, h, x, y, shrink_by;
121 
122  // ignore first 2 frames - they may be empty
123  if (++cd->frame_nb > 0) {
124  // Reset the crop area every reset_count frames, if reset_count is > 0
125  if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
126  cd->x1 = picref->video->w-1;
127  cd->y1 = picref->video->h-1;
128  cd->x2 = 0;
129  cd->y2 = 0;
130  cd->frame_nb = 1;
131  }
132 
133  for (y = 0; y < cd->y1; y++) {
134  if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
135  cd->y1 = y;
136  break;
137  }
138  }
139 
140  for (y = picref->video->h-1; y > cd->y2; y--) {
141  if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
142  cd->y2 = y;
143  break;
144  }
145  }
146 
147  for (y = 0; y < cd->x1; y++) {
148  if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
149  cd->x1 = y;
150  break;
151  }
152  }
153 
154  for (y = picref->video->w-1; y > cd->x2; y--) {
155  if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
156  cd->x2 = y;
157  break;
158  }
159  }
160 
161  // round x and y (up), important for yuv colorspaces
162  // make sure they stay rounded!
163  x = (cd->x1+1) & ~1;
164  y = (cd->y1+1) & ~1;
165 
166  w = cd->x2 - x + 1;
167  h = cd->y2 - y + 1;
168 
169  // w and h must be divisible by 2 as well because of yuv
170  // colorspace problems.
171  if (cd->round <= 1)
172  cd->round = 16;
173  if (cd->round % 2)
174  cd->round *= 2;
175 
176  shrink_by = w % cd->round;
177  w -= shrink_by;
178  x += (shrink_by/2 + 1) & ~1;
179 
180  shrink_by = h % cd->round;
181  h -= shrink_by;
182  y += (shrink_by/2 + 1) & ~1;
183 
184  av_log(ctx, AV_LOG_INFO,
185  "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pos:%"PRId64" pts:%"PRId64" t:%f crop=%d:%d:%d:%d\n",
186  cd->x1, cd->x2, cd->y1, cd->y2, w, h, x, y, picref->pos, picref->pts,
187  picref->pts == AV_NOPTS_VALUE ? -1 : picref->pts * av_q2d(inlink->time_base),
188  w, h, x, y);
189  }
190 
191  avfilter_end_frame(inlink->dst->outputs[0]);
192 }
193 
195  .name = "cropdetect",
196  .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
197 
198  .priv_size = sizeof(CropDetectContext),
199  .init = init,
200 
202 
203  .inputs = (AVFilterPad[]) {{ .name = "default",
204  .type = AVMEDIA_TYPE_VIDEO,
205  .config_props = config_input,
206  .get_video_buffer = avfilter_null_get_video_buffer,
207  .start_frame = avfilter_null_start_frame,
208  .end_frame = end_frame, },
209  { .name = NULL}},
210 
211  .outputs = (AVFilterPad[]) {{ .name = "default",
212  .type = AVMEDIA_TYPE_VIDEO },
213  { .name = NULL}},
214 };