2 * Copyright (c) 2005 Robert Edele <yartrebo@earthlink.net>
3 * Copyright (c) 2012 Stefano Sabatini
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
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 GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Advanced blur-based logo removing filter
26 * This filter loads an image mask file showing where a logo is and
27 * uses a blur transform to remove the logo.
29 * Based on the libmpcodecs remove-logo filter by Robert Edele.
33 * This code implements a filter to remove annoying TV logos and other annoying
34 * images placed onto a video stream. It works by filling in the pixels that
35 * comprise the logo with neighboring pixels. The transform is very loosely
36 * based on a gaussian blur, but it is different enough to merit its own
37 * paragraph later on. It is a major improvement on the old delogo filter as it
38 * both uses a better blurring algorithm and uses a bitmap to use an arbitrary
39 * and generally much tighter fitting shape than a rectangle.
41 * The logo removal algorithm has two key points. The first is that it
42 * distinguishes between pixels in the logo and those not in the logo by using
43 * the passed-in bitmap. Pixels not in the logo are copied over directly without
44 * being modified and they also serve as source pixels for the logo
45 * fill-in. Pixels inside the logo have the mask applied.
47 * At init-time the bitmap is reprocessed internally, and the distance to the
48 * nearest edge of the logo (Manhattan distance), along with a little extra to
49 * remove rough edges, is stored in each pixel. This is done using an in-place
50 * erosion algorithm, and incrementing each pixel that survives any given
51 * erosion. Once every pixel is eroded, the maximum value is recorded, and a
52 * set of masks from size 0 to this size are generaged. The masks are circular
53 * binary masks, where each pixel within a radius N (where N is the size of the
54 * mask) is a 1, and all other pixels are a 0. Although a gaussian mask would be
55 * more mathematically accurate, a binary mask works better in practice because
56 * we generally do not use the central pixels in the mask (because they are in
57 * the logo region), and thus a gaussian mask will cause too little blur and
58 * thus a very unstable image.
60 * The mask is applied in a special way. Namely, only pixels in the mask that
61 * line up to pixels outside the logo are used. The dynamic mask size means that
62 * the mask is just big enough so that the edges touch pixels outside the logo,
63 * so the blurring is kept to a minimum and at least the first boundary
64 * condition is met (that the image function itself is continuous), even if the
65 * second boundary condition (that the derivative of the image function is
66 * continuous) is not met. A masking algorithm that does preserve the second
67 * boundary coundition (perhaps something based on a highly-modified bi-cubic
68 * algorithm) should offer even better results on paper, but the noise in a
69 * typical TV signal should make anything based on derivatives hopelessly noisy.
72 #include "libavutil/imgutils.h"
78 #include "lavfutils.h"
79 #include "lswsutils.h"
82 /* Stores our collection of masks. The first is for an array of
83 the second for the y axis, and the third for the x axis. */
88 uint8_t *full_mask_data;
89 FFBoundingBox full_mask_bbox;
90 uint8_t *half_mask_data;
91 FFBoundingBox half_mask_bbox;
95 * Choose a slightly larger mask size to improve performance.
97 * This function maps the absolute minimum mask size needed to the
98 * mask size we'll actually use. f(x) = x (the smallest that will
99 * work) will produce the sharpest results, but will be quite
100 * jittery. f(x) = 1.25x (what I'm using) is a good tradeoff in my
101 * opinion. This will calculate only at init-time, so you can put a
102 * long expression here without effecting performance.
104 #define apply_mask_fudge_factor(x) (((x) >> 2) + x)
107 * Pre-process an image to give distance information.
109 * This function takes a bitmap image and converts it in place into a
110 * distance image. A distance image is zero for pixels outside of the
111 * logo and is the Manhattan distance (|dx| + |dy|) from the logo edge
112 * for pixels inside of the logo. This will overestimate the distance,
113 * but that is safe, and is far easier to implement than a proper
114 * pythagorean distance since I'm using a modified erosion algorithm
115 * to compute the distances.
117 * @param mask image which will be converted from a greyscale image
118 * into a distance image.
120 static void convert_mask_to_strength_mask(uint8_t *data, int linesize,
121 int w, int h, int min_val,
126 /* How many times we've gone through the loop. Used in the
127 in-place erosion algorithm and to get us max_mask_size later on. */
128 int current_pass = 0;
130 /* set all non-zero values to 1 */
131 for (y = 0; y < h; y++)
132 for (x = 0; x < w; x++)
133 data[y*linesize + x] = data[y*linesize + x] > min_val;
135 /* For each pass, if a pixel is itself the same value as the
136 current pass, and its four neighbors are too, then it is
137 incremented. If no pixels are incremented by the end of the
138 pass, then we go again. Edge pixels are counted as always
139 excluded (this should be true anyway for any sane mask, but if
140 it isn't this will ensure that we eventually exit). */
142 /* If this doesn't get set by the end of this pass, then we're done. */
143 int has_anything_changed = 0;
144 uint8_t *current_pixel0 = data, *current_pixel;
147 for (y = 1; y < h-1; y++) {
148 current_pixel = current_pixel0;
149 for (x = 1; x < w-1; x++) {
150 /* Apply the in-place erosion transform. It is based
151 on the following two premises:
152 1 - Any pixel that fails 1 erosion will fail all
155 2 - Only pixels having survived all erosions up to
156 the present will be >= to current_pass.
157 It doesn't matter if it survived the current pass,
158 failed it, or hasn't been tested yet. By using >=
159 instead of ==, we allow the algorithm to work in
161 if ( *current_pixel >= current_pass &&
162 *(current_pixel + 1) >= current_pass &&
163 *(current_pixel - 1) >= current_pass &&
164 *(current_pixel + w) >= current_pass &&
165 *(current_pixel - w) >= current_pass) {
166 /* Increment the value since it still has not been
167 * eroded, as evidenced by the if statement that
168 * just evaluated to true. */
170 has_anything_changed = 1;
174 current_pixel0 += linesize;
176 if (!has_anything_changed)
180 /* Apply the fudge factor, which will increase the size of the
181 * mask a little to reduce jitter at the cost of more blur. */
182 for (y = 1; y < h - 1; y++)
183 for (x = 1; x < w - 1; x++)
184 data[(y * linesize) + x] = apply_mask_fudge_factor(data[(y * linesize) + x]);
186 /* As a side-effect, we now know the maximum mask size, which
187 * we'll use to generate our masks. */
188 /* Apply the fudge factor to this number too, since we must ensure
189 * that enough masks are generated. */
190 *max_mask_size = apply_mask_fudge_factor(current_pass + 1);
193 static int query_formats(AVFilterContext *ctx)
195 static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE };
196 ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
200 static int load_mask(uint8_t **mask, int *w, int *h,
201 const char *filename, void *log_ctx)
204 enum AVPixelFormat pix_fmt;
205 uint8_t *src_data[4], *gray_data[4];
206 int src_linesize[4], gray_linesize[4];
208 /* load image from file */
209 if ((ret = ff_load_image(src_data, src_linesize, w, h, &pix_fmt, filename, log_ctx)) < 0)
212 /* convert the image to GRAY8 */
213 if ((ret = ff_scale_image(gray_data, gray_linesize, *w, *h, AV_PIX_FMT_GRAY8,
214 src_data, src_linesize, *w, *h, pix_fmt,
218 /* copy mask to a newly allocated array */
219 *mask = av_malloc(*w * *h);
221 ret = AVERROR(ENOMEM);
222 av_image_copy_plane(*mask, *w, gray_data[0], gray_linesize[0], *w, *h);
225 av_free(src_data[0]);
226 av_free(gray_data[0]);
231 * Generate a scaled down image with half width, height, and intensity.
233 * This function not only scales down an image, but halves the value
234 * in each pixel too. The purpose of this is to produce a chroma
235 * filter image out of a luma filter image. The pixel values store the
236 * distance to the edge of the logo and halving the dimensions halves
237 * the distance. This function rounds up, because a downwards rounding
238 * error could cause the filter to fail, but an upwards rounding error
239 * will only cause a minor amount of excess blur in the chroma planes.
241 static void generate_half_size_image(const uint8_t *src_data, int src_linesize,
242 uint8_t *dst_data, int dst_linesize,
243 int src_w, int src_h,
248 /* Copy over the image data, using the average of 4 pixels for to
249 * calculate each downsampled pixel. */
250 for (y = 0; y < src_h/2; y++) {
251 for (x = 0; x < src_w/2; x++) {
252 /* Set the pixel if there exists a non-zero value in the
253 * source pixels, else clear it. */
254 dst_data[(y * dst_linesize) + x] =
255 src_data[((y << 1) * src_linesize) + (x << 1)] ||
256 src_data[((y << 1) * src_linesize) + (x << 1) + 1] ||
257 src_data[(((y << 1) + 1) * src_linesize) + (x << 1)] ||
258 src_data[(((y << 1) + 1) * src_linesize) + (x << 1) + 1];
259 dst_data[(y * dst_linesize) + x] = FFMIN(1, dst_data[(y * dst_linesize) + x]);
263 convert_mask_to_strength_mask(dst_data, dst_linesize,
264 src_w/2, src_h/2, 0, max_mask_size);
267 static av_cold int init(AVFilterContext *ctx, const char *args)
269 RemovelogoContext *removelogo = ctx->priv;
273 int full_max_mask_size, half_max_mask_size;
276 av_log(ctx, AV_LOG_ERROR, "An image file must be specified as argument\n");
277 return AVERROR(EINVAL);
280 /* Load our mask image. */
281 if ((ret = load_mask(&removelogo->full_mask_data, &w, &h, args, ctx)) < 0)
283 removelogo->mask_w = w;
284 removelogo->mask_h = h;
286 convert_mask_to_strength_mask(removelogo->full_mask_data, w, w, h,
287 16, &full_max_mask_size);
289 /* Create the scaled down mask image for the chroma planes. */
290 if (!(removelogo->half_mask_data = av_mallocz(w/2 * h/2)))
291 return AVERROR(ENOMEM);
292 generate_half_size_image(removelogo->full_mask_data, w,
293 removelogo->half_mask_data, w/2,
294 w, h, &half_max_mask_size);
296 removelogo->max_mask_size = FFMAX(full_max_mask_size, half_max_mask_size);
298 /* Create a circular mask for each size up to max_mask_size. When
299 the filter is applied, the mask size is determined on a pixel
300 by pixel basis, with pixels nearer the edge of the logo getting
301 smaller mask sizes. */
302 mask = (int ***)av_malloc(sizeof(int **) * (removelogo->max_mask_size + 1));
304 return AVERROR(ENOMEM);
306 for (a = 0; a <= removelogo->max_mask_size; a++) {
307 mask[a] = (int **)av_malloc(sizeof(int *) * ((a * 2) + 1));
309 return AVERROR(ENOMEM);
310 for (b = -a; b <= a; b++) {
311 mask[a][b + a] = (int *)av_malloc(sizeof(int) * ((a * 2) + 1));
313 return AVERROR(ENOMEM);
314 for (c = -a; c <= a; c++) {
315 if ((b * b) + (c * c) <= (a * a)) /* Circular 0/1 mask. */
316 mask[a][b + a][c + a] = 1;
318 mask[a][b + a][c + a] = 0;
322 removelogo->mask = mask;
324 /* Calculate our bounding rectangles, which determine in what
325 * region the logo resides for faster processing. */
326 ff_calculate_bounding_box(&removelogo->full_mask_bbox, removelogo->full_mask_data, w, w, h, 0);
327 ff_calculate_bounding_box(&removelogo->half_mask_bbox, removelogo->half_mask_data, w/2, w/2, h/2, 0);
329 #define SHOW_LOGO_INFO(mask_type) \
330 av_log(ctx, AV_LOG_VERBOSE, #mask_type " x1:%d x2:%d y1:%d y2:%d max_mask_size:%d\n", \
331 removelogo->mask_type##_mask_bbox.x1, removelogo->mask_type##_mask_bbox.x2, \
332 removelogo->mask_type##_mask_bbox.y1, removelogo->mask_type##_mask_bbox.y2, \
333 mask_type##_max_mask_size);
334 SHOW_LOGO_INFO(full);
335 SHOW_LOGO_INFO(half);
340 static int config_props_input(AVFilterLink *inlink)
342 AVFilterContext *ctx = inlink->dst;
343 RemovelogoContext *removelogo = ctx->priv;
345 if (inlink->w != removelogo->mask_w || inlink->h != removelogo->mask_h) {
346 av_log(ctx, AV_LOG_INFO,
347 "Mask image size %dx%d does not match with the input video size %dx%d\n",
348 removelogo->mask_w, removelogo->mask_h, inlink->w, inlink->h);
349 return AVERROR(EINVAL);
358 * It takes a pixel that is inside the mask and blurs it. It does so
359 * by finding the average of all the pixels within the mask and
360 * outside of the mask.
362 * @param mask_data the mask plane to use for averaging
363 * @param image_data the image plane to blur
364 * @param w width of the image
365 * @param h height of the image
366 * @param x x-coordinate of the pixel to blur
367 * @param y y-coordinate of the pixel to blur
369 static unsigned int blur_pixel(int ***mask,
370 const uint8_t *mask_data, int mask_linesize,
371 uint8_t *image_data, int image_linesize,
372 int w, int h, int x, int y)
374 /* Mask size tells how large a circle to use. The radius is about
375 * (slightly larger than) mask size. */
377 int start_posx, start_posy, end_posx, end_posy;
379 unsigned int accumulator = 0, divisor = 0;
380 /* What pixel we are reading out of the circular blur mask. */
381 const uint8_t *image_read_position;
382 /* What pixel we are reading out of the filter image. */
383 const uint8_t *mask_read_position;
385 /* Prepare our bounding rectangle and clip it if need be. */
386 mask_size = mask_data[y * mask_linesize + x];
387 start_posx = FFMAX(0, x - mask_size);
388 start_posy = FFMAX(0, y - mask_size);
389 end_posx = FFMIN(w - 1, x + mask_size);
390 end_posy = FFMIN(h - 1, y + mask_size);
392 image_read_position = image_data + image_linesize * start_posy + start_posx;
393 mask_read_position = mask_data + mask_linesize * start_posy + start_posx;
395 for (j = start_posy; j <= end_posy; j++) {
396 for (i = start_posx; i <= end_posx; i++) {
397 /* Check if this pixel is in the mask or not. Only use the
398 * pixel if it is not. */
399 if (!(*mask_read_position) && mask[mask_size][i - start_posx][j - start_posy]) {
400 accumulator += *image_read_position;
404 image_read_position++;
405 mask_read_position++;
408 image_read_position += (image_linesize - ((end_posx + 1) - start_posx));
409 mask_read_position += (mask_linesize - ((end_posx + 1) - start_posx));
412 /* If divisor is 0, it means that not a single pixel is outside of
413 the logo, so we have no data. Else we need to normalise the
414 data using the divisor. */
415 return divisor == 0 ? 255:
416 (accumulator + (divisor / 2)) / divisor; /* divide, taking into account average rounding error */
420 * Blur image plane using a mask.
422 * @param source The image to have it's logo removed.
423 * @param destination Where the output image will be stored.
424 * @param source_stride How far apart (in memory) two consecutive lines are.
425 * @param destination Same as source_stride, but for the destination image.
426 * @param width Width of the image. This is the same for source and destination.
427 * @param height Height of the image. This is the same for source and destination.
428 * @param is_image_direct If the image is direct, then source and destination are
429 * the same and we can save a lot of time by not copying pixels that
431 * @param filter The image that stores the distance to the edge of the logo for
433 * @param logo_start_x smallest x-coordinate that contains at least 1 logo pixel.
434 * @param logo_start_y smallest y-coordinate that contains at least 1 logo pixel.
435 * @param logo_end_x largest x-coordinate that contains at least 1 logo pixel.
436 * @param logo_end_y largest y-coordinate that contains at least 1 logo pixel.
438 * This function processes an entire plane. Pixels outside of the logo are copied
439 * to the output without change, and pixels inside the logo have the de-blurring
442 static void blur_image(int ***mask,
443 const uint8_t *src_data, int src_linesize,
444 uint8_t *dst_data, int dst_linesize,
445 const uint8_t *mask_data, int mask_linesize,
446 int w, int h, int direct,
451 const uint8_t *src_line;
454 av_image_copy_plane(dst_data, dst_linesize, src_data, src_linesize, w, h);
456 for (y = bbox->y1; y <= bbox->y2; y++) {
457 src_line = src_data + src_linesize * y;
458 dst_line = dst_data + dst_linesize * y;
460 for (x = bbox->x1; x <= bbox->x2; x++) {
461 if (mask_data[y * mask_linesize + x]) {
462 /* Only process if we are in the mask. */
463 dst_line[x] = blur_pixel(mask,
464 mask_data, mask_linesize,
465 dst_data, dst_linesize,
468 /* Else just copy the data. */
470 dst_line[x] = src_line[x];
476 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
478 RemovelogoContext *removelogo = inlink->dst->priv;
479 AVFilterLink *outlink = inlink->dst->outputs[0];
480 AVFilterBufferRef *outpicref;
483 if (inpicref->perms & AV_PERM_WRITE) {
485 outpicref = inpicref;
487 outpicref = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
489 avfilter_unref_bufferp(&inpicref);
490 return AVERROR(ENOMEM);
492 avfilter_copy_buffer_ref_props(outpicref, inpicref);
495 blur_image(removelogo->mask,
496 inpicref ->data[0], inpicref ->linesize[0],
497 outpicref->data[0], outpicref->linesize[0],
498 removelogo->full_mask_data, inlink->w,
499 inlink->w, inlink->h, direct, &removelogo->full_mask_bbox);
500 blur_image(removelogo->mask,
501 inpicref ->data[1], inpicref ->linesize[1],
502 outpicref->data[1], outpicref->linesize[1],
503 removelogo->half_mask_data, inlink->w/2,
504 inlink->w/2, inlink->h/2, direct, &removelogo->half_mask_bbox);
505 blur_image(removelogo->mask,
506 inpicref ->data[2], inpicref ->linesize[2],
507 outpicref->data[2], outpicref->linesize[2],
508 removelogo->half_mask_data, inlink->w/2,
509 inlink->w/2, inlink->h/2, direct, &removelogo->half_mask_bbox);
512 avfilter_unref_bufferp(&inpicref);
514 return ff_filter_frame(outlink, outpicref);
517 static void uninit(AVFilterContext *ctx)
519 RemovelogoContext *removelogo = ctx->priv;
522 av_freep(&removelogo->full_mask_data);
523 av_freep(&removelogo->half_mask_data);
525 if (removelogo->mask) {
526 /* Loop through each mask. */
527 for (a = 0; a <= removelogo->max_mask_size; a++) {
528 /* Loop through each scanline in a mask. */
529 for (b = -a; b <= a; b++) {
530 av_free(removelogo->mask[a][b + a]); /* Free a scanline. */
532 av_free(removelogo->mask[a]);
534 /* Free the array of pointers pointing to the masks. */
535 av_freep(&removelogo->mask);
539 static const AVFilterPad removelogo_inputs[] = {
542 .type = AVMEDIA_TYPE_VIDEO,
543 .get_video_buffer = ff_null_get_video_buffer,
544 .config_props = config_props_input,
545 .filter_frame = filter_frame,
546 .min_perms = AV_PERM_READ,
551 static const AVFilterPad removelogo_outputs[] = {
554 .type = AVMEDIA_TYPE_VIDEO,
559 AVFilter avfilter_vf_removelogo = {
560 .name = "removelogo",
561 .description = NULL_IF_CONFIG_SMALL("Remove a TV logo based on a mask image."),
562 .priv_size = sizeof(RemovelogoContext),
565 .query_formats = query_formats,
566 .inputs = removelogo_inputs,
567 .outputs = removelogo_outputs,