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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 #include <stdio.h>
27 
28 #include "avfilter.h"
29 #include "formats.h"
30 #include "internal.h"
31 #include "video.h"
32 #include "libavutil/eval.h"
33 #include "libavutil/avstring.h"
34 #include "libavutil/internal.h"
35 #include "libavutil/libm.h"
36 #include "libavutil/imgutils.h"
37 #include "libavutil/mathematics.h"
38 #include "libavutil/opt.h"
39 
40 static const char *const var_names[] = {
41  "in_w", "iw", ///< width of the input video
42  "in_h", "ih", ///< height of the input video
43  "out_w", "ow", ///< width of the cropped video
44  "out_h", "oh", ///< height of the cropped video
45  "a",
46  "sar",
47  "dar",
48  "hsub",
49  "vsub",
50  "x",
51  "y",
52  "n", ///< number of frame
53  "pos", ///< position in the file
54  "t", ///< timestamp expressed in seconds
55  NULL
56 };
57 
58 enum var_name {
74 };
75 
76 typedef struct CropContext {
77  const AVClass *class;
78  int x; ///< x offset of the non-cropped area with respect to the input area
79  int y; ///< y offset of the non-cropped area with respect to the input area
80  int w; ///< width of the cropped area
81  int h; ///< height of the cropped area
82 
83  AVRational out_sar; ///< output sample aspect ratio
84  int keep_aspect; ///< keep display aspect ratio when cropping
85 
86  int max_step[4]; ///< max pixel step for each plane, expressed as a number of bytes
87  int hsub, vsub; ///< chroma subsampling
88  char *x_expr, *y_expr, *w_expr, *h_expr;
89  AVExpr *x_pexpr, *y_pexpr; /* parsed expressions for x and y */
91 } CropContext;
92 
94 {
96  int fmt;
97 
98  for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {
99  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
101  !((desc->log2_chroma_w || desc->log2_chroma_h) && !(desc->flags & AV_PIX_FMT_FLAG_PLANAR)))
102  ff_add_format(&formats, fmt);
103  }
104 
105  return ff_set_common_formats(ctx, formats);
106 }
107 
108 static av_cold void uninit(AVFilterContext *ctx)
109 {
110  CropContext *s = ctx->priv;
111 
112  av_expr_free(s->x_pexpr);
113  s->x_pexpr = NULL;
114  av_expr_free(s->y_pexpr);
115  s->y_pexpr = NULL;
116 }
117 
118 static inline int normalize_double(int *n, double d)
119 {
120  int ret = 0;
121 
122  if (isnan(d)) {
123  ret = AVERROR(EINVAL);
124  } else if (d > INT_MAX || d < INT_MIN) {
125  *n = d > INT_MAX ? INT_MAX : INT_MIN;
126  ret = AVERROR(EINVAL);
127  } else
128  *n = round(d);
129 
130  return ret;
131 }
132 
133 static int config_input(AVFilterLink *link)
134 {
135  AVFilterContext *ctx = link->dst;
136  CropContext *s = ctx->priv;
137  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(link->format);
138  int ret;
139  const char *expr;
140  double res;
141 
142  s->var_values[VAR_IN_W] = s->var_values[VAR_IW] = ctx->inputs[0]->w;
143  s->var_values[VAR_IN_H] = s->var_values[VAR_IH] = ctx->inputs[0]->h;
144  s->var_values[VAR_A] = (float) link->w / link->h;
147  s->var_values[VAR_HSUB] = 1<<pix_desc->log2_chroma_w;
148  s->var_values[VAR_VSUB] = 1<<pix_desc->log2_chroma_h;
149  s->var_values[VAR_X] = NAN;
150  s->var_values[VAR_Y] = NAN;
153  s->var_values[VAR_N] = 0;
154  s->var_values[VAR_T] = NAN;
155  s->var_values[VAR_POS] = NAN;
156 
158  s->hsub = pix_desc->log2_chroma_w;
159  s->vsub = pix_desc->log2_chroma_h;
160 
161  if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),
162  var_names, s->var_values,
163  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
164  goto fail_expr;
165  s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;
166  if ((ret = av_expr_parse_and_eval(&res, (expr = s->h_expr),
167  var_names, s->var_values,
168  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
169  goto fail_expr;
170  s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = res;
171  /* evaluate again ow as it may depend on oh */
172  if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),
173  var_names, s->var_values,
174  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
175  goto fail_expr;
176 
177  s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;
178  if (normalize_double(&s->w, s->var_values[VAR_OUT_W]) < 0 ||
179  normalize_double(&s->h, s->var_values[VAR_OUT_H]) < 0) {
180  av_log(ctx, AV_LOG_ERROR,
181  "Too big value or invalid expression for out_w/ow or out_h/oh. "
182  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
183  s->w_expr, s->h_expr);
184  return AVERROR(EINVAL);
185  }
186  s->w &= ~((1 << s->hsub) - 1);
187  s->h &= ~((1 << s->vsub) - 1);
188 
189  av_expr_free(s->x_pexpr);
190  av_expr_free(s->y_pexpr);
191  s->x_pexpr = s->y_pexpr = NULL;
192  if ((ret = av_expr_parse(&s->x_pexpr, s->x_expr, var_names,
193  NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
194  (ret = av_expr_parse(&s->y_pexpr, s->y_expr, var_names,
195  NULL, NULL, NULL, NULL, 0, ctx)) < 0)
196  return AVERROR(EINVAL);
197 
198  if (s->keep_aspect) {
200  (AVRational){ link->w, link->h });
201  av_reduce(&s->out_sar.num, &s->out_sar.den,
202  dar.num * s->h, dar.den * s->w, INT_MAX);
203  } else
204  s->out_sar = link->sample_aspect_ratio;
205 
206  av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d sar:%d/%d -> w:%d h:%d sar:%d/%d\n",
207  link->w, link->h, link->sample_aspect_ratio.num, link->sample_aspect_ratio.den,
208  s->w, s->h, s->out_sar.num, s->out_sar.den);
209 
210  if (s->w <= 0 || s->h <= 0 ||
211  s->w > link->w || s->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  s->w, s->h);
215  return AVERROR(EINVAL);
216  }
217 
218  /* set default, required in the case the first computed value for x/y is NAN */
219  s->x = (link->w - s->w) / 2;
220  s->y = (link->h - s->h) / 2;
221  s->x &= ~((1 << s->hsub) - 1);
222  s->y &= ~((1 << s->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 *s = link->src->priv;
233 
234  link->w = s->w;
235  link->h = s->h;
236  link->sample_aspect_ratio = s->out_sar;
237 
238  return 0;
239 }
240 
242 {
243  AVFilterContext *ctx = link->dst;
244  CropContext *s = ctx->priv;
245  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
246  int i;
247 
248  frame->width = s->w;
249  frame->height = s->h;
250 
251  s->var_values[VAR_N] = link->frame_count;
252  s->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
253  NAN : frame->pts * av_q2d(link->time_base);
254  s->var_values[VAR_POS] = av_frame_get_pkt_pos(frame) == -1 ?
255  NAN : av_frame_get_pkt_pos(frame);
259 
262 
263  if (s->x < 0)
264  s->x = 0;
265  if (s->y < 0)
266  s->y = 0;
267  if ((unsigned)s->x + (unsigned)s->w > link->w)
268  s->x = link->w - s->w;
269  if ((unsigned)s->y + (unsigned)s->h > link->h)
270  s->y = link->h - s->h;
271  s->x &= ~((1 << s->hsub) - 1);
272  s->y &= ~((1 << s->vsub) - 1);
273 
274  av_log(ctx, AV_LOG_TRACE, "n:%d t:%f pos:%f x:%d y:%d x+w:%d y+h:%d\n",
275  (int)s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
276  s->x, s->y, s->x+s->w, s->y+s->h);
277 
278  frame->data[0] += s->y * frame->linesize[0];
279  frame->data[0] += s->x * s->max_step[0];
280 
281  if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)) {
282  for (i = 1; i < 3; i ++) {
283  if (frame->data[i]) {
284  frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
285  frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;
286  }
287  }
288  }
289 
290  /* alpha plane */
291  if (frame->data[3]) {
292  frame->data[3] += s->y * frame->linesize[3];
293  frame->data[3] += s->x * s->max_step[3];
294  }
295 
296  return ff_filter_frame(link->dst->outputs[0], frame);
297 }
298 
299 #define OFFSET(x) offsetof(CropContext, x)
300 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
301 
302 static const AVOption crop_options[] = {
303  { "out_w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
304  { "w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
305  { "out_h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
306  { "h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
307  { "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 },
308  { "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 },
309  { "keep_aspect", "keep aspect ratio", OFFSET(keep_aspect), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS },
310  { NULL }
311 };
312 
314 
316  {
317  .name = "default",
318  .type = AVMEDIA_TYPE_VIDEO,
319  .filter_frame = filter_frame,
320  .config_props = config_input,
321  },
322  { NULL }
323 };
324 
326  {
327  .name = "default",
328  .type = AVMEDIA_TYPE_VIDEO,
329  .config_props = config_output,
330  },
331  { NULL }
332 };
333 
335  .name = "crop",
336  .description = NULL_IF_CONFIG_SMALL("Crop the input video."),
337  .priv_size = sizeof(CropContext),
338  .priv_class = &crop_class,
340  .uninit = uninit,
341  .inputs = avfilter_vf_crop_inputs,
342  .outputs = avfilter_vf_crop_outputs,
343 };