vf_crop.c
Go to the documentation of this file.
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 <stdio.h>
29 
30 #include "avfilter.h"
31 #include "formats.h"
32 #include "internal.h"
33 #include "video.h"
34 #include "libavutil/eval.h"
35 #include "libavutil/avstring.h"
36 #include "libavutil/internal.h"
37 #include "libavutil/libm.h"
38 #include "libavutil/imgutils.h"
39 #include "libavutil/mathematics.h"
40 
41 static const char *const var_names[] = {
42  "E",
43  "PHI",
44  "PI",
45  "in_w", "iw",
46  "in_h", "ih",
47  "out_w", "ow",
48  "out_h", "oh",
49  "x",
50  "y",
51  "n",
52  "pos",
53  "t",
54  NULL
55 };
56 
57 enum var_name {
71 };
72 
73 typedef struct {
74  int x;
75  int y;
76  int w;
77  int h;
78 
79  int max_step[4];
80  int hsub, vsub;
81  char x_expr[256], y_expr[256], ow_expr[256], oh_expr[256];
82  AVExpr *x_pexpr, *y_pexpr; /* parsed expressions for x and y */
83  double var_values[VAR_VARS_NB];
84 } CropContext;
85 
87 {
88  static const enum AVPixelFormat pix_fmts[] = {
112  };
113 
115 
116  return 0;
117 }
118 
119 static av_cold int init(AVFilterContext *ctx, const char *args)
120 {
121  CropContext *crop = ctx->priv;
122 
123  av_strlcpy(crop->ow_expr, "iw", sizeof(crop->ow_expr));
124  av_strlcpy(crop->oh_expr, "ih", sizeof(crop->oh_expr));
125  av_strlcpy(crop->x_expr, "(in_w-out_w)/2", sizeof(crop->x_expr));
126  av_strlcpy(crop->y_expr, "(in_h-out_h)/2", sizeof(crop->y_expr));
127 
128  if (args)
129  sscanf(args, "%255[^:]:%255[^:]:%255[^:]:%255[^:]", crop->ow_expr, crop->oh_expr, crop->x_expr, crop->y_expr);
130 
131  return 0;
132 }
133 
134 static av_cold void uninit(AVFilterContext *ctx)
135 {
136  CropContext *crop = ctx->priv;
137 
138  av_expr_free(crop->x_pexpr); crop->x_pexpr = NULL;
139  av_expr_free(crop->y_pexpr); crop->y_pexpr = NULL;
140 }
141 
142 static inline int normalize_double(int *n, double d)
143 {
144  int ret = 0;
145 
146  if (isnan(d)) {
147  ret = AVERROR(EINVAL);
148  } else if (d > INT_MAX || d < INT_MIN) {
149  *n = d > INT_MAX ? INT_MAX : INT_MIN;
150  ret = AVERROR(EINVAL);
151  } else
152  *n = round(d);
153 
154  return ret;
155 }
156 
157 static int config_input(AVFilterLink *link)
158 {
159  AVFilterContext *ctx = link->dst;
160  CropContext *crop = ctx->priv;
161  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(link->format);
162  int ret;
163  const char *expr;
164  double res;
165 
166  crop->var_values[VAR_E] = M_E;
167  crop->var_values[VAR_PHI] = M_PHI;
168  crop->var_values[VAR_PI] = M_PI;
169  crop->var_values[VAR_IN_W] = crop->var_values[VAR_IW] = ctx->inputs[0]->w;
170  crop->var_values[VAR_IN_H] = crop->var_values[VAR_IH] = ctx->inputs[0]->h;
171  crop->var_values[VAR_X] = NAN;
172  crop->var_values[VAR_Y] = NAN;
173  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = NAN;
174  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = NAN;
175  crop->var_values[VAR_N] = 0;
176  crop->var_values[VAR_T] = NAN;
177  crop->var_values[VAR_POS] = NAN;
178 
179  av_image_fill_max_pixsteps(crop->max_step, NULL, pix_desc);
180  crop->hsub = pix_desc->log2_chroma_w;
181  crop->vsub = pix_desc->log2_chroma_h;
182 
183  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),
184  var_names, crop->var_values,
185  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
186  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
187  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->oh_expr),
188  var_names, crop->var_values,
189  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
190  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = res;
191  /* evaluate again ow as it may depend on oh */
192  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),
193  var_names, crop->var_values,
194  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
195  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
196  if (normalize_double(&crop->w, crop->var_values[VAR_OUT_W]) < 0 ||
197  normalize_double(&crop->h, crop->var_values[VAR_OUT_H]) < 0) {
198  av_log(ctx, AV_LOG_ERROR,
199  "Too big value or invalid expression for out_w/ow or out_h/oh. "
200  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
201  crop->ow_expr, crop->oh_expr);
202  return AVERROR(EINVAL);
203  }
204  crop->w &= ~((1 << crop->hsub) - 1);
205  crop->h &= ~((1 << crop->vsub) - 1);
206 
207  if ((ret = av_expr_parse(&crop->x_pexpr, crop->x_expr, var_names,
208  NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
209  (ret = av_expr_parse(&crop->y_pexpr, crop->y_expr, var_names,
210  NULL, NULL, NULL, NULL, 0, ctx)) < 0)
211  return AVERROR(EINVAL);
212 
213  av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d -> w:%d h:%d\n",
214  link->w, link->h, crop->w, crop->h);
215 
216  if (crop->w <= 0 || crop->h <= 0 ||
217  crop->w > link->w || crop->h > link->h) {
218  av_log(ctx, AV_LOG_ERROR,
219  "Invalid too big or non positive size for width '%d' or height '%d'\n",
220  crop->w, crop->h);
221  return AVERROR(EINVAL);
222  }
223 
224  /* set default, required in the case the first computed value for x/y is NAN */
225  crop->x = (link->w - crop->w) / 2;
226  crop->y = (link->h - crop->h) / 2;
227  crop->x &= ~((1 << crop->hsub) - 1);
228  crop->y &= ~((1 << crop->vsub) - 1);
229  return 0;
230 
231 fail_expr:
232  av_log(NULL, AV_LOG_ERROR, "Error when evaluating the expression '%s'\n", expr);
233  return ret;
234 }
235 
236 static int config_output(AVFilterLink *link)
237 {
238  CropContext *crop = link->src->priv;
239 
240  link->w = crop->w;
241  link->h = crop->h;
242 
243  return 0;
244 }
245 
246 static int filter_frame(AVFilterLink *link, AVFilterBufferRef *frame)
247 {
248  AVFilterContext *ctx = link->dst;
249  CropContext *crop = ctx->priv;
250  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
251  int i;
252 
253  frame->video->w = crop->w;
254  frame->video->h = crop->h;
255 
256  crop->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
257  NAN : frame->pts * av_q2d(link->time_base);
258  crop->var_values[VAR_POS] = frame->pos == -1 ? NAN : frame->pos;
259  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
260  crop->var_values[VAR_Y] = av_expr_eval(crop->y_pexpr, crop->var_values, NULL);
261  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
262 
263  normalize_double(&crop->x, crop->var_values[VAR_X]);
264  normalize_double(&crop->y, crop->var_values[VAR_Y]);
265 
266  if (crop->x < 0) crop->x = 0;
267  if (crop->y < 0) crop->y = 0;
268  if ((unsigned)crop->x + (unsigned)crop->w > link->w) crop->x = link->w - crop->w;
269  if ((unsigned)crop->y + (unsigned)crop->h > link->h) crop->y = link->h - crop->h;
270  crop->x &= ~((1 << crop->hsub) - 1);
271  crop->y &= ~((1 << crop->vsub) - 1);
272 
273  av_dlog(ctx, "n:%d t:%f x:%d y:%d x+w:%d y+h:%d\n",
274  (int)crop->var_values[VAR_N], crop->var_values[VAR_T], crop->x,
275  crop->y, crop->x+crop->w, crop->y+crop->h);
276 
277  frame->data[0] += crop->y * frame->linesize[0];
278  frame->data[0] += crop->x * crop->max_step[0];
279 
280  if (!(desc->flags & PIX_FMT_PAL || desc->flags & PIX_FMT_PSEUDOPAL)) {
281  for (i = 1; i < 3; i ++) {
282  if (frame->data[i]) {
283  frame->data[i] += (crop->y >> crop->vsub) * frame->linesize[i];
284  frame->data[i] += (crop->x * crop->max_step[i]) >> crop->hsub;
285  }
286  }
287  }
288 
289  /* alpha plane */
290  if (frame->data[3]) {
291  frame->data[3] += crop->y * frame->linesize[3];
292  frame->data[3] += crop->x * crop->max_step[3];
293  }
294 
295  crop->var_values[VAR_N] += 1.0;
296 
297  return ff_filter_frame(link->dst->outputs[0], frame);
298 }
299 
301  {
302  .name = "default",
303  .type = AVMEDIA_TYPE_VIDEO,
304  .filter_frame = filter_frame,
305  .get_video_buffer = ff_null_get_video_buffer,
306  .config_props = config_input,
307  },
308  { NULL }
309 };
310 
312  {
313  .name = "default",
314  .type = AVMEDIA_TYPE_VIDEO,
315  .config_props = config_output,
316  },
317  { NULL }
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 = avfilter_vf_crop_inputs,
331  .outputs = avfilter_vf_crop_outputs,
332 };