vf_boxblur.c
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1 /*
2  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (c) 2011 Stefano Sabatini
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * Libav 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 Libav; if not, write to the Free Software Foundation, Inc.,
19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20  */
21 
28 #include "libavutil/avstring.h"
29 #include "libavutil/eval.h"
30 #include "libavutil/pixdesc.h"
31 #include "avfilter.h"
32 
33 static const char *var_names[] = {
34  "w",
35  "h",
36  "cw",
37  "ch",
38  "hsub",
39  "vsub",
40  NULL
41 };
42 
43 enum var_name {
51 };
52 
53 typedef struct {
54  int radius;
55  int power;
56 } FilterParam;
57 
58 typedef struct {
62  char luma_radius_expr [256];
63  char chroma_radius_expr[256];
64  char alpha_radius_expr [256];
65 
66  int hsub, vsub;
67  int radius[4];
68  int power[4];
69  uint8_t *temp[2];
71 
72 #define Y 0
73 #define U 1
74 #define V 2
75 #define A 3
76 
77 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
78 {
79  BoxBlurContext *boxblur = ctx->priv;
80  int e;
81 
82  if (!args) {
83  av_log(ctx, AV_LOG_ERROR,
84  "Filter expects 2 or 4 or 6 arguments, none provided\n");
85  return AVERROR(EINVAL);
86  }
87 
88  e = sscanf(args, "%255[^:]:%d:%255[^:]:%d:%255[^:]:%d",
89  boxblur->luma_radius_expr, &boxblur->luma_param .power,
90  boxblur->chroma_radius_expr, &boxblur->chroma_param.power,
91  boxblur->alpha_radius_expr, &boxblur->alpha_param .power);
92 
93  if (e != 2 && e != 4 && e != 6) {
94  av_log(ctx, AV_LOG_ERROR,
95  "Filter expects 2 or 4 or 6 params, provided %d\n", e);
96  return AVERROR(EINVAL);
97  }
98 
99  if (e < 4) {
100  boxblur->chroma_param.power = boxblur->luma_param.power;
102  sizeof(boxblur->chroma_radius_expr));
103  }
104  if (e < 6) {
105  boxblur->alpha_param.power = boxblur->luma_param.power;
106  av_strlcpy(boxblur->alpha_radius_expr, boxblur->luma_radius_expr,
107  sizeof(boxblur->alpha_radius_expr));
108  }
109 
110  return 0;
111 }
112 
113 static av_cold void uninit(AVFilterContext *ctx)
114 {
115  BoxBlurContext *boxblur = ctx->priv;
116 
117  av_freep(&boxblur->temp[0]);
118  av_freep(&boxblur->temp[1]);
119 }
120 
122 {
123  enum PixelFormat pix_fmts[] = {
130  };
131 
133  return 0;
134 }
135 
136 static int config_input(AVFilterLink *inlink)
137 {
138  const AVPixFmtDescriptor *desc = &av_pix_fmt_descriptors[inlink->format];
139  AVFilterContext *ctx = inlink->dst;
140  BoxBlurContext *boxblur = ctx->priv;
141  int w = inlink->w, h = inlink->h;
142  int cw, ch;
143  double var_values[VARS_NB], res;
144  char *expr;
145  int ret;
146 
147  av_freep(&boxblur->temp[0]);
148  av_freep(&boxblur->temp[1]);
149  if (!(boxblur->temp[0] = av_malloc(FFMAX(w, h))))
150  return AVERROR(ENOMEM);
151  if (!(boxblur->temp[1] = av_malloc(FFMAX(w, h)))) {
152  av_freep(&boxblur->temp[0]);
153  return AVERROR(ENOMEM);
154  }
155 
156  boxblur->hsub = desc->log2_chroma_w;
157  boxblur->vsub = desc->log2_chroma_h;
158 
159  var_values[VAR_W] = inlink->w;
160  var_values[VAR_H] = inlink->h;
161  var_values[VAR_CW] = cw = w>>boxblur->hsub;
162  var_values[VAR_CH] = ch = h>>boxblur->vsub;
163  var_values[VAR_HSUB] = 1<<boxblur->hsub;
164  var_values[VAR_VSUB] = 1<<boxblur->vsub;
165 
166 #define EVAL_RADIUS_EXPR(comp) \
167  expr = boxblur->comp##_radius_expr; \
168  ret = av_expr_parse_and_eval(&res, expr, var_names, var_values, \
169  NULL, NULL, NULL, NULL, NULL, 0, ctx); \
170  boxblur->comp##_param.radius = res; \
171  if (ret < 0) { \
172  av_log(NULL, AV_LOG_ERROR, \
173  "Error when evaluating " #comp " radius expression '%s'\n", expr); \
174  return ret; \
175  }
176  EVAL_RADIUS_EXPR(luma);
177  EVAL_RADIUS_EXPR(chroma);
178  EVAL_RADIUS_EXPR(alpha);
179 
180  av_log(ctx, AV_LOG_DEBUG,
181  "luma_radius:%d luma_power:%d "
182  "chroma_radius:%d chroma_power:%d "
183  "alpha_radius:%d alpha_power:%d "
184  "w:%d chroma_w:%d h:%d chroma_h:%d\n",
185  boxblur->luma_param .radius, boxblur->luma_param .power,
186  boxblur->chroma_param.radius, boxblur->chroma_param.power,
187  boxblur->alpha_param .radius, boxblur->alpha_param .power,
188  w, cw, h, ch);
189 
190 #define CHECK_RADIUS_VAL(w_, h_, comp) \
191  if (boxblur->comp##_param.radius < 0 || \
192  2*boxblur->comp##_param.radius > FFMIN(w_, h_)) { \
193  av_log(ctx, AV_LOG_ERROR, \
194  "Invalid " #comp " radius value %d, must be >= 0 and <= %d\n", \
195  boxblur->comp##_param.radius, FFMIN(w_, h_)/2); \
196  return AVERROR(EINVAL); \
197  }
198  CHECK_RADIUS_VAL(w, h, luma);
199  CHECK_RADIUS_VAL(cw, ch, chroma);
200  CHECK_RADIUS_VAL(w, h, alpha);
201 
202  boxblur->radius[Y] = boxblur->luma_param.radius;
203  boxblur->radius[U] = boxblur->radius[V] = boxblur->chroma_param.radius;
204  boxblur->radius[A] = boxblur->alpha_param.radius;
205 
206  boxblur->power[Y] = boxblur->luma_param.power;
207  boxblur->power[U] = boxblur->power[V] = boxblur->chroma_param.power;
208  boxblur->power[A] = boxblur->alpha_param.power;
209 
210  return 0;
211 }
212 
213 static inline void blur(uint8_t *dst, int dst_step, const uint8_t *src, int src_step,
214  int len, int radius)
215 {
216  /* Naive boxblur would sum source pixels from x-radius .. x+radius
217  * for destination pixel x. That would be O(radius*width).
218  * If you now look at what source pixels represent 2 consecutive
219  * output pixels, then you see they are almost identical and only
220  * differ by 2 pixels, like:
221  * src0 111111111
222  * dst0 1
223  * src1 111111111
224  * dst1 1
225  * src0-src1 1 -1
226  * so when you know one output pixel you can find the next by just adding
227  * and subtracting 1 input pixel.
228  * The following code adopts this faster variant.
229  */
230  const int length = radius*2 + 1;
231  const int inv = ((1<<16) + length/2)/length;
232  int x, sum = 0;
233 
234  for (x = 0; x < radius; x++)
235  sum += src[x*src_step]<<1;
236  sum += src[radius*src_step];
237 
238  for (x = 0; x <= radius; x++) {
239  sum += src[(radius+x)*src_step] - src[(radius-x)*src_step];
240  dst[x*dst_step] = (sum*inv + (1<<15))>>16;
241  }
242 
243  for (; x < len-radius; x++) {
244  sum += src[(radius+x)*src_step] - src[(x-radius-1)*src_step];
245  dst[x*dst_step] = (sum*inv + (1<<15))>>16;
246  }
247 
248  for (; x < len; x++) {
249  sum += src[(2*len-radius-x-1)*src_step] - src[(x-radius-1)*src_step];
250  dst[x*dst_step] = (sum*inv + (1<<15))>>16;
251  }
252 }
253 
254 static inline void blur_power(uint8_t *dst, int dst_step, const uint8_t *src, int src_step,
255  int len, int radius, int power, uint8_t *temp[2])
256 {
257  uint8_t *a = temp[0], *b = temp[1];
258 
259  if (radius && power) {
260  blur(a, 1, src, src_step, len, radius);
261  for (; power > 2; power--) {
262  uint8_t *c;
263  blur(b, 1, a, 1, len, radius);
264  c = a; a = b; b = c;
265  }
266  if (power > 1) {
267  blur(dst, dst_step, a, 1, len, radius);
268  } else {
269  int i;
270  for (i = 0; i < len; i++)
271  dst[i*dst_step] = a[i];
272  }
273  } else {
274  int i;
275  for (i = 0; i < len; i++)
276  dst[i*dst_step] = src[i*src_step];
277  }
278 }
279 
280 static void hblur(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize,
281  int w, int h, int radius, int power, uint8_t *temp[2])
282 {
283  int y;
284 
285  if (radius == 0 && dst == src)
286  return;
287 
288  for (y = 0; y < h; y++)
289  blur_power(dst + y*dst_linesize, 1, src + y*src_linesize, 1,
290  w, radius, power, temp);
291 }
292 
293 static void vblur(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize,
294  int w, int h, int radius, int power, uint8_t *temp[2])
295 {
296  int x;
297 
298  if (radius == 0 && dst == src)
299  return;
300 
301  for (x = 0; x < w; x++)
302  blur_power(dst + x, dst_linesize, src + x, src_linesize,
303  h, radius, power, temp);
304 }
305 
306 static void draw_slice(AVFilterLink *inlink, int y0, int h0, int slice_dir)
307 {
308  AVFilterContext *ctx = inlink->dst;
309  BoxBlurContext *boxblur = ctx->priv;
310  AVFilterLink *outlink = inlink->dst->outputs[0];
311  AVFilterBufferRef *inpicref = inlink ->cur_buf;
312  AVFilterBufferRef *outpicref = outlink->out_buf;
313  int plane;
314  int cw = inlink->w >> boxblur->hsub, ch = h0 >> boxblur->vsub;
315  int w[4] = { inlink->w, cw, cw, inlink->w };
316  int h[4] = { h0, ch, ch, h0 };
317 
318  for (plane = 0; inpicref->data[plane] && plane < 4; plane++)
319  hblur(outpicref->data[plane], outpicref->linesize[plane],
320  inpicref ->data[plane], inpicref ->linesize[plane],
321  w[plane], h[plane], boxblur->radius[plane], boxblur->power[plane],
322  boxblur->temp);
323 
324  for (plane = 0; inpicref->data[plane] && plane < 4; plane++)
325  vblur(outpicref->data[plane], outpicref->linesize[plane],
326  outpicref->data[plane], outpicref->linesize[plane],
327  w[plane], h[plane], boxblur->radius[plane], boxblur->power[plane],
328  boxblur->temp);
329 
330  avfilter_draw_slice(outlink, y0, h0, slice_dir);
331 }
332 
334  .name = "boxblur",
335  .description = NULL_IF_CONFIG_SMALL("Blur the input."),
336  .priv_size = sizeof(BoxBlurContext),
337  .init = init,
338  .uninit = uninit,
340 
341  .inputs = (AVFilterPad[]) {{ .name = "default",
342  .type = AVMEDIA_TYPE_VIDEO,
343  .config_props = config_input,
344  .draw_slice = draw_slice,
345  .min_perms = AV_PERM_READ },
346  { .name = NULL}},
347  .outputs = (AVFilterPad[]) {{ .name = "default",
348  .type = AVMEDIA_TYPE_VIDEO, },
349  { .name = NULL}},
350 };