vf_crop.c
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1 /*
2  * Copyright (c) 2007 Bobby Bingham
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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.
10  *
11  * Libav 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.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
26 /* #define DEBUG */
27 
28 #include "avfilter.h"
29 #include "libavutil/eval.h"
30 #include "libavutil/avstring.h"
31 #include "libavutil/libm.h"
32 #include "libavutil/imgutils.h"
33 #include "libavutil/mathematics.h"
34 
35 static const char *var_names[] = {
36  "E",
37  "PHI",
38  "PI",
39  "in_w", "iw",
40  "in_h", "ih",
41  "out_w", "ow",
42  "out_h", "oh",
43  "x",
44  "y",
45  "n",
46  "pos",
47  "t",
48  NULL
49 };
50 
51 enum var_name {
65 };
66 
67 typedef struct {
68  int x;
69  int y;
70  int w;
71  int h;
72 
73  int max_step[4];
74  int hsub, vsub;
75  char x_expr[256], y_expr[256], ow_expr[256], oh_expr[256];
76  AVExpr *x_pexpr, *y_pexpr; /* parsed expressions for x and y */
77  double var_values[VAR_VARS_NB];
78 } CropContext;
79 
81 {
82  static const enum PixelFormat pix_fmts[] = {
106  };
107 
109 
110  return 0;
111 }
112 
113 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
114 {
115  CropContext *crop = ctx->priv;
116 
117  av_strlcpy(crop->ow_expr, "iw", sizeof(crop->ow_expr));
118  av_strlcpy(crop->oh_expr, "ih", sizeof(crop->oh_expr));
119  av_strlcpy(crop->x_expr, "(in_w-out_w)/2", sizeof(crop->x_expr));
120  av_strlcpy(crop->y_expr, "(in_h-out_h)/2", sizeof(crop->y_expr));
121 
122  if (args)
123  sscanf(args, "%255[^:]:%255[^:]:%255[^:]:%255[^:]", crop->ow_expr, crop->oh_expr, crop->x_expr, crop->y_expr);
124 
125  return 0;
126 }
127 
128 static av_cold void uninit(AVFilterContext *ctx)
129 {
130  CropContext *crop = ctx->priv;
131 
132  av_expr_free(crop->x_pexpr); crop->x_pexpr = NULL;
133  av_expr_free(crop->y_pexpr); crop->y_pexpr = NULL;
134 }
135 
136 static inline int normalize_double(int *n, double d)
137 {
138  int ret = 0;
139 
140  if (isnan(d)) {
141  ret = AVERROR(EINVAL);
142  } else if (d > INT_MAX || d < INT_MIN) {
143  *n = d > INT_MAX ? INT_MAX : INT_MIN;
144  ret = AVERROR(EINVAL);
145  } else
146  *n = round(d);
147 
148  return ret;
149 }
150 
151 static int config_input(AVFilterLink *link)
152 {
153  AVFilterContext *ctx = link->dst;
154  CropContext *crop = ctx->priv;
155  const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[link->format];
156  int ret;
157  const char *expr;
158  double res;
159 
160  crop->var_values[VAR_E] = M_E;
161  crop->var_values[VAR_PHI] = M_PHI;
162  crop->var_values[VAR_PI] = M_PI;
163  crop->var_values[VAR_IN_W] = crop->var_values[VAR_IW] = ctx->inputs[0]->w;
164  crop->var_values[VAR_IN_H] = crop->var_values[VAR_IH] = ctx->inputs[0]->h;
165  crop->var_values[VAR_X] = NAN;
166  crop->var_values[VAR_Y] = NAN;
167  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = NAN;
168  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = NAN;
169  crop->var_values[VAR_N] = 0;
170  crop->var_values[VAR_T] = NAN;
171  crop->var_values[VAR_POS] = NAN;
172 
173  av_image_fill_max_pixsteps(crop->max_step, NULL, pix_desc);
176 
177  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),
178  var_names, crop->var_values,
179  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
180  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
181  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->oh_expr),
182  var_names, crop->var_values,
183  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
184  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = res;
185  /* evaluate again ow as it may depend on oh */
186  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),
187  var_names, crop->var_values,
188  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
189  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
190  if (normalize_double(&crop->w, crop->var_values[VAR_OUT_W]) < 0 ||
191  normalize_double(&crop->h, crop->var_values[VAR_OUT_H]) < 0) {
192  av_log(ctx, AV_LOG_ERROR,
193  "Too big value or invalid expression for out_w/ow or out_h/oh. "
194  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
195  crop->ow_expr, crop->oh_expr);
196  return AVERROR(EINVAL);
197  }
198  crop->w &= ~((1 << crop->hsub) - 1);
199  crop->h &= ~((1 << crop->vsub) - 1);
200 
201  if ((ret = av_expr_parse(&crop->x_pexpr, crop->x_expr, var_names,
202  NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
203  (ret = av_expr_parse(&crop->y_pexpr, crop->y_expr, var_names,
204  NULL, NULL, NULL, NULL, 0, ctx)) < 0)
205  return AVERROR(EINVAL);
206 
207  av_log(ctx, AV_LOG_INFO, "w:%d h:%d -> w:%d h:%d\n",
208  link->w, link->h, crop->w, crop->h);
209 
210  if (crop->w <= 0 || crop->h <= 0 ||
211  crop->w > link->w || crop->h > link->h) {
212  av_log(ctx, AV_LOG_ERROR,
213  "Invalid too big or non positive size for width '%d' or height '%d'\n",
214  crop->w, crop->h);
215  return AVERROR(EINVAL);
216  }
217 
218  /* set default, required in the case the first computed value for x/y is NAN */
219  crop->x = (link->w - crop->w) / 2;
220  crop->y = (link->h - crop->h) / 2;
221  crop->x &= ~((1 << crop->hsub) - 1);
222  crop->y &= ~((1 << crop->vsub) - 1);
223  return 0;
224 
225 fail_expr:
226  av_log(NULL, AV_LOG_ERROR, "Error when evaluating the expression '%s'\n", expr);
227  return ret;
228 }
229 
230 static int config_output(AVFilterLink *link)
231 {
232  CropContext *crop = link->src->priv;
233 
234  link->w = crop->w;
235  link->h = crop->h;
236 
237  return 0;
238 }
239 
240 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
241 {
242  AVFilterContext *ctx = link->dst;
243  CropContext *crop = ctx->priv;
244  AVFilterBufferRef *ref2;
245  int i;
246 
247  ref2 = avfilter_ref_buffer(picref, ~0);
248  ref2->video->w = crop->w;
249  ref2->video->h = crop->h;
250 
251  crop->var_values[VAR_T] = picref->pts == AV_NOPTS_VALUE ?
252  NAN : picref->pts * av_q2d(link->time_base);
253  crop->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;
254  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
255  crop->var_values[VAR_Y] = av_expr_eval(crop->y_pexpr, crop->var_values, NULL);
256  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
257 
258  normalize_double(&crop->x, crop->var_values[VAR_X]);
259  normalize_double(&crop->y, crop->var_values[VAR_Y]);
260 
261  if (crop->x < 0) crop->x = 0;
262  if (crop->y < 0) crop->y = 0;
263  if ((unsigned)crop->x + (unsigned)crop->w > link->w) crop->x = link->w - crop->w;
264  if ((unsigned)crop->y + (unsigned)crop->h > link->h) crop->y = link->h - crop->h;
265  crop->x &= ~((1 << crop->hsub) - 1);
266  crop->y &= ~((1 << crop->vsub) - 1);
267 
268  av_dlog(ctx, "n:%d t:%f x:%d y:%d x+w:%d y+h:%d\n",
269  (int)crop->var_values[VAR_N], crop->var_values[VAR_T], crop->x,
270  crop->y, crop->x+crop->w, crop->y+crop->h);
271 
272  ref2->data[0] += crop->y * ref2->linesize[0];
273  ref2->data[0] += crop->x * crop->max_step[0];
274 
276  for (i = 1; i < 3; i ++) {
277  if (ref2->data[i]) {
278  ref2->data[i] += (crop->y >> crop->vsub) * ref2->linesize[i];
279  ref2->data[i] += (crop->x * crop->max_step[i]) >> crop->hsub;
280  }
281  }
282  }
283 
284  /* alpha plane */
285  if (ref2->data[3]) {
286  ref2->data[3] += crop->y * ref2->linesize[3];
287  ref2->data[3] += crop->x * crop->max_step[3];
288  }
289 
290  avfilter_start_frame(link->dst->outputs[0], ref2);
291 }
292 
293 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
294 {
295  AVFilterContext *ctx = link->dst;
296  CropContext *crop = ctx->priv;
297 
298  if (y >= crop->y + crop->h || y + h <= crop->y)
299  return;
300 
301  if (y < crop->y) {
302  h -= crop->y - y;
303  y = crop->y;
304  }
305  if (y + h > crop->y + crop->h)
306  h = crop->y + crop->h - y;
307 
308  avfilter_draw_slice(ctx->outputs[0], y - crop->y, h, slice_dir);
309 }
310 
311 static void end_frame(AVFilterLink *link)
312 {
313  CropContext *crop = link->dst->priv;
314 
315  crop->var_values[VAR_N] += 1.0;
317  avfilter_end_frame(link->dst->outputs[0]);
318 }
319 
321  .name = "crop",
322  .description = NULL_IF_CONFIG_SMALL("Crop the input video to width:height:x:y."),
323 
324  .priv_size = sizeof(CropContext),
325 
327  .init = init,
328  .uninit = uninit,
329 
330  .inputs = (AVFilterPad[]) {{ .name = "default",
331  .type = AVMEDIA_TYPE_VIDEO,
332  .start_frame = start_frame,
333  .draw_slice = draw_slice,
334  .end_frame = end_frame,
335  .get_video_buffer = avfilter_null_get_video_buffer,
336  .config_props = config_input, },
337  { .name = NULL}},
338  .outputs = (AVFilterPad[]) {{ .name = "default",
339  .type = AVMEDIA_TYPE_VIDEO,
340  .config_props = config_output, },
341  { .name = NULL}},
342 };