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vf_crop.c
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1 /*
2  * Copyright (c) 2007 Bobby Bingham
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * video crop filter
24  */
25 
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 #include "libavutil/opt.h"
41 
42 static const char *const var_names[] = {
43  "in_w", "iw", ///< width of the input video
44  "in_h", "ih", ///< height of the input video
45  "out_w", "ow", ///< width of the cropped video
46  "out_h", "oh", ///< height of the cropped video
47  "a",
48  "sar",
49  "dar",
50  "hsub",
51  "vsub",
52  "x",
53  "y",
54  "n", ///< number of frame
55  "pos", ///< position in the file
56  "t", ///< timestamp expressed in seconds
57  NULL
58 };
59 
60 enum var_name {
76 };
77 
78 typedef struct {
79  const AVClass *class;
80  int x; ///< x offset of the non-cropped area with respect to the input area
81  int y; ///< y offset of the non-cropped area with respect to the input area
82  int w; ///< width of the cropped area
83  int h; ///< height of the cropped area
84 
85  AVRational out_sar; ///< output sample aspect ratio
86  int keep_aspect; ///< keep display aspect ratio when cropping
87 
88  int max_step[4]; ///< max pixel step for each plane, expressed as a number of bytes
89  int hsub, vsub; ///< chroma subsampling
90  char *x_expr, *y_expr, *w_expr, *h_expr;
91  AVExpr *x_pexpr, *y_pexpr; /* parsed expressions for x and y */
92  double var_values[VAR_VARS_NB];
93 } CropContext;
94 
95 #define OFFSET(x) offsetof(CropContext, x)
96 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
97 
98 static const AVOption crop_options[] = {
99  { "x", "set the x crop area expression", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "(in_w-out_w)/2"}, CHAR_MIN, CHAR_MAX, FLAGS },
100  { "y", "set the y crop area expression", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "(in_h-out_h)/2"}, CHAR_MIN, CHAR_MAX, FLAGS },
101  { "out_w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
102  { "w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
103  { "out_h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
104  { "h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
105  { "keep_aspect", "keep aspect ratio", OFFSET(keep_aspect), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS },
106  {NULL}
107 };
108 
110 
111 static av_cold int init(AVFilterContext *ctx, const char *args)
112 {
113  CropContext *crop = ctx->priv;
114  static const char *shorthand[] = { "w", "h", "x", "y", "keep_aspect", NULL };
115 
116  crop->class = &crop_class;
117  av_opt_set_defaults(crop);
118 
119  return av_opt_set_from_string(crop, args, shorthand, "=", ":");
120 }
121 
122 static av_cold void uninit(AVFilterContext *ctx)
123 {
124  CropContext *crop = ctx->priv;
125 
126  av_expr_free(crop->x_pexpr); crop->x_pexpr = NULL;
127  av_expr_free(crop->y_pexpr); crop->y_pexpr = NULL;
128  av_opt_free(crop);
129 }
130 
132 {
133  static const enum AVPixelFormat pix_fmts[] = {
157  };
158 
160 
161  return 0;
162 }
163 
164 static inline int normalize_double(int *n, double d)
165 {
166  int ret = 0;
167 
168  if (isnan(d)) {
169  ret = AVERROR(EINVAL);
170  } else if (d > INT_MAX || d < INT_MIN) {
171  *n = d > INT_MAX ? INT_MAX : INT_MIN;
172  ret = AVERROR(EINVAL);
173  } else
174  *n = round(d);
175 
176  return ret;
177 }
178 
179 static int config_input(AVFilterLink *link)
180 {
181  AVFilterContext *ctx = link->dst;
182  CropContext *crop = ctx->priv;
183  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(link->format);
184  int ret;
185  const char *expr;
186  double res;
187 
188  crop->var_values[VAR_IN_W] = crop->var_values[VAR_IW] = ctx->inputs[0]->w;
189  crop->var_values[VAR_IN_H] = crop->var_values[VAR_IH] = ctx->inputs[0]->h;
190  crop->var_values[VAR_A] = (float) link->w / link->h;
192  crop->var_values[VAR_DAR] = crop->var_values[VAR_A] * crop->var_values[VAR_SAR];
193  crop->var_values[VAR_HSUB] = 1<<pix_desc->log2_chroma_w;
194  crop->var_values[VAR_VSUB] = 1<<pix_desc->log2_chroma_h;
195  crop->var_values[VAR_X] = NAN;
196  crop->var_values[VAR_Y] = NAN;
197  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = NAN;
198  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = NAN;
199  crop->var_values[VAR_N] = 0;
200  crop->var_values[VAR_T] = NAN;
201  crop->var_values[VAR_POS] = NAN;
202 
203  av_image_fill_max_pixsteps(crop->max_step, NULL, pix_desc);
204  crop->hsub = pix_desc->log2_chroma_w;
205  crop->vsub = pix_desc->log2_chroma_h;
206 
207  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->w_expr),
208  var_names, crop->var_values,
209  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
210  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
211  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->h_expr),
212  var_names, crop->var_values,
213  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
214  crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = res;
215  /* evaluate again ow as it may depend on oh */
216  if ((ret = av_expr_parse_and_eval(&res, (expr = crop->w_expr),
217  var_names, crop->var_values,
218  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;
219  crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
220  if (normalize_double(&crop->w, crop->var_values[VAR_OUT_W]) < 0 ||
221  normalize_double(&crop->h, crop->var_values[VAR_OUT_H]) < 0) {
222  av_log(ctx, AV_LOG_ERROR,
223  "Too big value or invalid expression for out_w/ow or out_h/oh. "
224  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
225  crop->w_expr, crop->h_expr);
226  return AVERROR(EINVAL);
227  }
228  crop->w &= ~((1 << crop->hsub) - 1);
229  crop->h &= ~((1 << crop->vsub) - 1);
230 
231  if ((ret = av_expr_parse(&crop->x_pexpr, crop->x_expr, var_names,
232  NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
233  (ret = av_expr_parse(&crop->y_pexpr, crop->y_expr, var_names,
234  NULL, NULL, NULL, NULL, 0, ctx)) < 0)
235  return AVERROR(EINVAL);
236 
237  if (crop->keep_aspect) {
239  (AVRational){ link->w, link->h });
240  av_reduce(&crop->out_sar.num, &crop->out_sar.den,
241  dar.num * crop->h, dar.den * crop->w, INT_MAX);
242  } else
243  crop->out_sar = link->sample_aspect_ratio;
244 
245  av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d sar:%d/%d -> w:%d h:%d sar:%d/%d\n",
246  link->w, link->h, link->sample_aspect_ratio.num, link->sample_aspect_ratio.den,
247  crop->w, crop->h, crop->out_sar.num, crop->out_sar.den);
248 
249  if (crop->w <= 0 || crop->h <= 0 ||
250  crop->w > link->w || crop->h > link->h) {
251  av_log(ctx, AV_LOG_ERROR,
252  "Invalid too big or non positive size for width '%d' or height '%d'\n",
253  crop->w, crop->h);
254  return AVERROR(EINVAL);
255  }
256 
257  /* set default, required in the case the first computed value for x/y is NAN */
258  crop->x = (link->w - crop->w) / 2;
259  crop->y = (link->h - crop->h) / 2;
260  crop->x &= ~((1 << crop->hsub) - 1);
261  crop->y &= ~((1 << crop->vsub) - 1);
262  return 0;
263 
264 fail_expr:
265  av_log(NULL, AV_LOG_ERROR, "Error when evaluating the expression '%s'\n", expr);
266  return ret;
267 }
268 
269 static int config_output(AVFilterLink *link)
270 {
271  CropContext *crop = link->src->priv;
272 
273  link->w = crop->w;
274  link->h = crop->h;
275  link->sample_aspect_ratio = crop->out_sar;
276 
277  return 0;
278 }
279 
281 {
282  AVFilterContext *ctx = link->dst;
283  CropContext *crop = ctx->priv;
284  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
285  int i;
286 
287  frame->video->w = crop->w;
288  frame->video->h = crop->h;
289 
290  crop->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
291  NAN : frame->pts * av_q2d(link->time_base);
292  crop->var_values[VAR_POS] = frame->pos == -1 ? NAN : frame->pos;
293  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
294  crop->var_values[VAR_Y] = av_expr_eval(crop->y_pexpr, crop->var_values, NULL);
295  crop->var_values[VAR_X] = av_expr_eval(crop->x_pexpr, crop->var_values, NULL);
296 
297  normalize_double(&crop->x, crop->var_values[VAR_X]);
298  normalize_double(&crop->y, crop->var_values[VAR_Y]);
299 
300  if (crop->x < 0) crop->x = 0;
301  if (crop->y < 0) crop->y = 0;
302  if ((unsigned)crop->x + (unsigned)crop->w > link->w) crop->x = link->w - crop->w;
303  if ((unsigned)crop->y + (unsigned)crop->h > link->h) crop->y = link->h - crop->h;
304  crop->x &= ~((1 << crop->hsub) - 1);
305  crop->y &= ~((1 << crop->vsub) - 1);
306 
307  av_dlog(ctx, "n:%d t:%f x:%d y:%d x+w:%d y+h:%d\n",
308  (int)crop->var_values[VAR_N], crop->var_values[VAR_T], crop->x,
309  crop->y, crop->x+crop->w, crop->y+crop->h);
310 
311  frame->data[0] += crop->y * frame->linesize[0];
312  frame->data[0] += crop->x * crop->max_step[0];
313 
314  if (!(desc->flags & PIX_FMT_PAL || desc->flags & PIX_FMT_PSEUDOPAL)) {
315  for (i = 1; i < 3; i ++) {
316  if (frame->data[i]) {
317  frame->data[i] += (crop->y >> crop->vsub) * frame->linesize[i];
318  frame->data[i] += (crop->x * crop->max_step[i]) >> crop->hsub;
319  }
320  }
321  }
322 
323  /* alpha plane */
324  if (frame->data[3]) {
325  frame->data[3] += crop->y * frame->linesize[3];
326  frame->data[3] += crop->x * crop->max_step[3];
327  }
328 
329  crop->var_values[VAR_N] += 1.0;
330 
331  return ff_filter_frame(link->dst->outputs[0], frame);
332 }
333 
335  {
336  .name = "default",
337  .type = AVMEDIA_TYPE_VIDEO,
338  .filter_frame = filter_frame,
339  .get_video_buffer = ff_null_get_video_buffer,
340  .config_props = config_input,
341  },
342  { NULL }
343 };
344 
346  {
347  .name = "default",
348  .type = AVMEDIA_TYPE_VIDEO,
349  .config_props = config_output,
350  },
351  { NULL }
352 };
353 
355  .name = "crop",
356  .description = NULL_IF_CONFIG_SMALL("Crop the input video to width:height:x:y."),
357 
358  .priv_size = sizeof(CropContext),
359 
361  .init = init,
362  .uninit = uninit,
363 
364  .inputs = avfilter_vf_crop_inputs,
365  .outputs = avfilter_vf_crop_outputs,
366  .priv_class = &crop_class,
367 };