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vf_perspective.c
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1 /*
2  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (c) 2013 Paul B Mahol
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public
9  * License as published by the Free Software Foundation; either
10  * version 2 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/eval.h"
23 #include "libavutil/imgutils.h"
24 #include "libavutil/pixdesc.h"
25 #include "libavutil/opt.h"
26 #include "avfilter.h"
27 #include "formats.h"
28 #include "internal.h"
29 #include "video.h"
30 
31 #define SUB_PIXEL_BITS 8
32 #define SUB_PIXELS (1 << SUB_PIXEL_BITS)
33 #define COEFF_BITS 11
34 
35 #define LINEAR 0
36 #define CUBIC 1
37 
38 typedef struct PerspectiveContext {
39  const AVClass *class;
40  char *expr_str[4][2];
41  double ref[4][2];
42  int32_t (*pv)[2];
45  int linesize[4];
46  int height[4];
47  int hsub, vsub;
48  int nb_planes;
49 
51  uint8_t *dst, int dst_linesize,
52  uint8_t *src, int src_linesize,
53  int w, int h, int hsub, int vsub);
55 
56 #define OFFSET(x) offsetof(PerspectiveContext, x)
57 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
58 
59 static const AVOption perspective_options[] = {
60  { "x0", "set top left x coordinate", OFFSET(expr_str[0][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
61  { "y0", "set top left y coordinate", OFFSET(expr_str[0][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
62  { "x1", "set top right x coordinate", OFFSET(expr_str[1][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },
63  { "y1", "set top right y coordinate", OFFSET(expr_str[1][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
64  { "x2", "set bottom left x coordinate", OFFSET(expr_str[2][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
65  { "y2", "set bottom left y coordinate", OFFSET(expr_str[2][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },
66  { "x3", "set bottom right x coordinate", OFFSET(expr_str[3][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },
67  { "y3", "set bottom right y coordinate", OFFSET(expr_str[3][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },
68  { "interpolation", "set interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },
69  { "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "interpolation" },
70  { "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC}, 0, 0, FLAGS, "interpolation" },
71  { NULL }
72 };
73 
75 
77 {
78  static const enum AVPixelFormat pix_fmts[] = {
83  };
84 
86  return 0;
87 }
88 
89 static inline double get_coeff(double d)
90 {
91  double coeff, A = -0.60;
92 
93  d = fabs(d);
94 
95  if (d < 1.0)
96  coeff = (1.0 - (A + 3.0) * d * d + (A + 2.0) * d * d * d);
97  else if (d < 2.0)
98  coeff = (-4.0 * A + 8.0 * A * d - 5.0 * A * d * d + A * d * d * d);
99  else
100  coeff = 0.0;
101 
102  return coeff;
103 }
104 
105 static const char *const var_names[] = { "W", "H", NULL };
107 
108 static int config_input(AVFilterLink *inlink)
109 {
110  double x0, x1, x2, x3, x4, x5, x6, x7, q;
111  AVFilterContext *ctx = inlink->dst;
112  PerspectiveContext *s = ctx->priv;
113  double (*ref)[2] = s->ref;
114  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
115  double values[VAR_VARS_NB] = { [VAR_W] = inlink->w, [VAR_H] = inlink->h };
116  int h = inlink->h;
117  int w = inlink->w;
118  int x, y, i, j, ret;
119 
120  for (i = 0; i < 4; i++) {
121  for (j = 0; j < 2; j++) {
122  if (!s->expr_str[i][j])
123  return AVERROR(EINVAL);
124  ret = av_expr_parse_and_eval(&s->ref[i][j], s->expr_str[i][j],
125  var_names, &values[0],
126  NULL, NULL, NULL, NULL,
127  0, 0, ctx);
128  if (ret < 0)
129  return ret;
130  }
131  }
132 
133  s->hsub = desc->log2_chroma_w;
134  s->vsub = desc->log2_chroma_h;
136  if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)
137  return ret;
138 
139  s->height[1] = s->height[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
140  s->height[0] = s->height[3] = inlink->h;
141 
142  s->pv = av_realloc_f(s->pv, w * h, 2 * sizeof(*s->pv));
143  if (!s->pv)
144  return AVERROR(ENOMEM);
145 
146  x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
147  (ref[2][1] - ref[3][1]) -
148  ( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
149  (ref[2][0] - ref[3][0])) * h;
150  x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
151  (ref[1][0] - ref[3][0]) -
152  ( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
153  (ref[1][1] - ref[3][1])) * w;
154  q = ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -
155  ( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);
156 
157  x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];
158  x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];
159  x2 = q * ref[0][0] * w * h;
160  x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];
161  x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];
162  x5 = q * ref[0][1] * w * h;
163 
164  for (y = 0; y < h; y++){
165  for (x = 0; x < w; x++){
166  int u, v;
167 
168  u = (int)floor(SUB_PIXELS * (x0 * x + x1 * y + x2) /
169  (x6 * x + x7 * y + q * w * h) + 0.5);
170  v = (int)floor(SUB_PIXELS * (x3 * x + x4 * y + x5) /
171  (x6 * x + x7 * y + q * w * h) + 0.5);
172 
173  s->pv[x + y * w][0] = u;
174  s->pv[x + y * w][1] = v;
175  }
176  }
177 
178  for (i = 0; i < SUB_PIXELS; i++){
179  double d = i / (double)SUB_PIXELS;
180  double temp[4];
181  double sum = 0;
182 
183  for (j = 0; j < 4; j++)
184  temp[j] = get_coeff(j - d - 1);
185 
186  for (j = 0; j < 4; j++)
187  sum += temp[j];
188 
189  for (j = 0; j < 4; j++)
190  s->coeff[i][j] = (int)floor((1 << COEFF_BITS) * temp[j] / sum + 0.5);
191  }
192 
193  return 0;
194 }
195 
197  uint8_t *dst, int dst_linesize,
198  uint8_t *src, int src_linesize,
199  int w, int h, int hsub, int vsub)
200 {
201  const int linesize = s->linesize[0];
202  int x, y;
203 
204  for (y = 0; y < h; y++) {
205  int sy = y << vsub;
206  for (x = 0; x < w; x++) {
207  int u, v, subU, subV, sum, sx;
208 
209  sx = x << hsub;
210  u = s->pv[sx + sy * linesize][0] >> hsub;
211  v = s->pv[sx + sy * linesize][1] >> vsub;
212  subU = u & (SUB_PIXELS - 1);
213  subV = v & (SUB_PIXELS - 1);
214  u >>= SUB_PIXEL_BITS;
215  v >>= SUB_PIXEL_BITS;
216 
217  if (u > 0 && v > 0 && u < w - 2 && v < h - 2){
218  const int index = u + v*src_linesize;
219  const int a = s->coeff[subU][0];
220  const int b = s->coeff[subU][1];
221  const int c = s->coeff[subU][2];
222  const int d = s->coeff[subU][3];
223 
224  sum = s->coeff[subV][0] * (a * src[index - 1 - src_linesize] + b * src[index - 0 - src_linesize] +
225  c * src[index + 1 - src_linesize] + d * src[index + 2 - src_linesize]) +
226  s->coeff[subV][1] * (a * src[index - 1 ] + b * src[index - 0 ] +
227  c * src[index + 1 ] + d * src[index + 2 ]) +
228  s->coeff[subV][2] * (a * src[index - 1 + src_linesize] + b * src[index - 0 + src_linesize] +
229  c * src[index + 1 + src_linesize] + d * src[index + 2 + src_linesize]) +
230  s->coeff[subV][3] * (a * src[index - 1 + 2 * src_linesize] + b * src[index - 0 + 2 * src_linesize] +
231  c * src[index + 1 + 2 * src_linesize] + d * src[index + 2 + 2 * src_linesize]);
232  } else {
233  int dx, dy;
234 
235  sum = 0;
236 
237  for (dy = 0; dy < 4; dy++) {
238  int iy = v + dy - 1;
239 
240  if (iy < 0)
241  iy = 0;
242  else if (iy >= h)
243  iy = h-1;
244  for (dx = 0; dx < 4; dx++) {
245  int ix = u + dx - 1;
246 
247  if (ix < 0)
248  ix = 0;
249  else if (ix >= w)
250  ix = w - 1;
251 
252  sum += s->coeff[subU][dx] * s->coeff[subV][dy] * src[ ix + iy * src_linesize];
253  }
254  }
255  }
256 
257  sum = (sum + (1<<(COEFF_BITS * 2 - 1))) >> (COEFF_BITS * 2);
258  sum = av_clip(sum, 0, 255);
259  dst[x + y * dst_linesize] = sum;
260  }
261  }
262 }
263 
265  uint8_t *dst, int dst_linesize,
266  uint8_t *src, int src_linesize,
267  int w, int h, int hsub, int vsub)
268 {
269  const int linesize = s->linesize[0];
270  int x, y;
271 
272  for (y = 0; y < h; y++){
273  int sy = y << vsub;
274  for (x = 0; x < w; x++){
275  int u, v, subU, subV, sum, sx, index, subUI, subVI;
276 
277  sx = x << hsub;
278  u = s->pv[sx + sy * linesize][0] >> hsub;
279  v = s->pv[sx + sy * linesize][1] >> vsub;
280  subU = u & (SUB_PIXELS - 1);
281  subV = v & (SUB_PIXELS - 1);
282  u >>= SUB_PIXEL_BITS;
283  v >>= SUB_PIXEL_BITS;
284 
285  index = u + v * src_linesize;
286  subUI = SUB_PIXELS - subU;
287  subVI = SUB_PIXELS - subV;
288 
289  if ((unsigned)u < (unsigned)(w - 1)){
290  if((unsigned)v < (unsigned)(h - 1)){
291  sum = subVI * (subUI * src[index] + subU * src[index + 1]) +
292  subV * (subUI * src[index + src_linesize] + subU * src[index + src_linesize + 1]);
293  sum = (sum + (1 << (SUB_PIXEL_BITS * 2 - 1)))>> (SUB_PIXEL_BITS * 2);
294  } else {
295  if (v < 0)
296  v = 0;
297  else
298  v = h - 1;
299  index = u + v * src_linesize;
300  sum = subUI * src[index] + subU * src[index + 1];
301  sum = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;
302  }
303  } else {
304  if (u < 0)
305  u = 0;
306  else
307  u = w - 1;
308  if ((unsigned)v < (unsigned)(h - 1)){
309  index = u + v * src_linesize;
310  sum = subVI * src[index] + subV * src[index + src_linesize];
311  sum = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;
312  } else {
313  if (v < 0)
314  v = 0;
315  else
316  v = h - 1;
317  index = u + v * src_linesize;
318  sum = src[index];
319  }
320  }
321 
322  sum = av_clip(sum, 0, 255);
323  dst[x + y * dst_linesize] = sum;
324  }
325  }
326 }
327 
328 static av_cold int init(AVFilterContext *ctx)
329 {
330  PerspectiveContext *s = ctx->priv;
331 
332  switch (s->interpolation) {
333  case LINEAR: s->perspective = resample_linear; break;
334  case CUBIC: s->perspective = resample_cubic; break;
335  }
336 
337  return 0;
338 }
339 
340 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
341 {
342  AVFilterContext *ctx = inlink->dst;
343  AVFilterLink *outlink = ctx->outputs[0];
344  PerspectiveContext *s = ctx->priv;
345  AVFrame *out;
346  int plane;
347 
348  out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
349  if (!out) {
350  av_frame_free(&frame);
351  return AVERROR(ENOMEM);
352  }
353  av_frame_copy_props(out, frame);
354 
355  for (plane = 0; plane < s->nb_planes; plane++) {
356  int hsub = plane == 1 || plane == 2 ? s->hsub : 0;
357  int vsub = plane == 1 || plane == 2 ? s->vsub : 0;
358  s->perspective(s, out->data[plane], out->linesize[plane],
359  frame->data[plane], frame->linesize[plane],
360  s->linesize[plane], s->height[plane], hsub, vsub);
361  }
362 
363  av_frame_free(&frame);
364  return ff_filter_frame(outlink, out);
365 }
366 
367 static av_cold void uninit(AVFilterContext *ctx)
368 {
369  PerspectiveContext *s = ctx->priv;
370 
371  av_freep(&s->pv);
372 }
373 
374 static const AVFilterPad perspective_inputs[] = {
375  {
376  .name = "default",
377  .type = AVMEDIA_TYPE_VIDEO,
378  .filter_frame = filter_frame,
379  .config_props = config_input,
380  },
381  { NULL }
382 };
383 
385  {
386  .name = "default",
387  .type = AVMEDIA_TYPE_VIDEO,
388  },
389  { NULL }
390 };
391 
393  .name = "perspective",
394  .description = NULL_IF_CONFIG_SMALL("Correct the perspective of video."),
395  .priv_size = sizeof(PerspectiveContext),
396  .init = init,
397  .uninit = uninit,
399  .inputs = perspective_inputs,
400  .outputs = perspective_outputs,
401  .priv_class = &perspective_class,
403 };