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"
73 #include "libavutil/opt.h"
79 #include "lavfutils.h"
80 #include "lswsutils.h"
85 /* Stores our collection of masks. The first is for an array of
86 the second for the y axis, and the third for the x axis. */
91 uint8_t *full_mask_data;
92 FFBoundingBox full_mask_bbox;
93 uint8_t *half_mask_data;
94 FFBoundingBox half_mask_bbox;
97 #define OFFSET(x) offsetof(RemovelogoContext, x)
98 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
99 static const AVOption removelogo_options[] = {
100 { "filename", "set bitmap filename", OFFSET(filename), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
101 { "f", "set bitmap filename", OFFSET(filename), AV_OPT_TYPE_STRING, {.str=NULL}, .flags = FLAGS },
105 AVFILTER_DEFINE_CLASS(removelogo);
108 * Choose a slightly larger mask size to improve performance.
110 * This function maps the absolute minimum mask size needed to the
111 * mask size we'll actually use. f(x) = x (the smallest that will
112 * work) will produce the sharpest results, but will be quite
113 * jittery. f(x) = 1.25x (what I'm using) is a good tradeoff in my
114 * opinion. This will calculate only at init-time, so you can put a
115 * long expression here without effecting performance.
117 #define apply_mask_fudge_factor(x) (((x) >> 2) + x)
120 * Pre-process an image to give distance information.
122 * This function takes a bitmap image and converts it in place into a
123 * distance image. A distance image is zero for pixels outside of the
124 * logo and is the Manhattan distance (|dx| + |dy|) from the logo edge
125 * for pixels inside of the logo. This will overestimate the distance,
126 * but that is safe, and is far easier to implement than a proper
127 * pythagorean distance since I'm using a modified erosion algorithm
128 * to compute the distances.
130 * @param mask image which will be converted from a greyscale image
131 * into a distance image.
133 static void convert_mask_to_strength_mask(uint8_t *data, int linesize,
134 int w, int h, int min_val,
139 /* How many times we've gone through the loop. Used in the
140 in-place erosion algorithm and to get us max_mask_size later on. */
141 int current_pass = 0;
143 /* set all non-zero values to 1 */
144 for (y = 0; y < h; y++)
145 for (x = 0; x < w; x++)
146 data[y*linesize + x] = data[y*linesize + x] > min_val;
148 /* For each pass, if a pixel is itself the same value as the
149 current pass, and its four neighbors are too, then it is
150 incremented. If no pixels are incremented by the end of the
151 pass, then we go again. Edge pixels are counted as always
152 excluded (this should be true anyway for any sane mask, but if
153 it isn't this will ensure that we eventually exit). */
155 /* If this doesn't get set by the end of this pass, then we're done. */
156 int has_anything_changed = 0;
157 uint8_t *current_pixel0 = data, *current_pixel;
160 for (y = 1; y < h-1; y++) {
161 current_pixel = current_pixel0;
162 for (x = 1; x < w-1; x++) {
163 /* Apply the in-place erosion transform. It is based
164 on the following two premises:
165 1 - Any pixel that fails 1 erosion will fail all
168 2 - Only pixels having survived all erosions up to
169 the present will be >= to current_pass.
170 It doesn't matter if it survived the current pass,
171 failed it, or hasn't been tested yet. By using >=
172 instead of ==, we allow the algorithm to work in
174 if ( *current_pixel >= current_pass &&
175 *(current_pixel + 1) >= current_pass &&
176 *(current_pixel - 1) >= current_pass &&
177 *(current_pixel + w) >= current_pass &&
178 *(current_pixel - w) >= current_pass) {
179 /* Increment the value since it still has not been
180 * eroded, as evidenced by the if statement that
181 * just evaluated to true. */
183 has_anything_changed = 1;
187 current_pixel0 += linesize;
189 if (!has_anything_changed)
193 /* Apply the fudge factor, which will increase the size of the
194 * mask a little to reduce jitter at the cost of more blur. */
195 for (y = 1; y < h - 1; y++)
196 for (x = 1; x < w - 1; x++)
197 data[(y * linesize) + x] = apply_mask_fudge_factor(data[(y * linesize) + x]);
199 /* As a side-effect, we now know the maximum mask size, which
200 * we'll use to generate our masks. */
201 /* Apply the fudge factor to this number too, since we must ensure
202 * that enough masks are generated. */
203 *max_mask_size = apply_mask_fudge_factor(current_pass + 1);
206 static int query_formats(AVFilterContext *ctx)
208 static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE };
209 ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
213 static int load_mask(uint8_t **mask, int *w, int *h,
214 const char *filename, void *log_ctx)
217 enum AVPixelFormat pix_fmt;
218 uint8_t *src_data[4], *gray_data[4];
219 int src_linesize[4], gray_linesize[4];
221 /* load image from file */
222 if ((ret = ff_load_image(src_data, src_linesize, w, h, &pix_fmt, filename, log_ctx)) < 0)
225 /* convert the image to GRAY8 */
226 if ((ret = ff_scale_image(gray_data, gray_linesize, *w, *h, AV_PIX_FMT_GRAY8,
227 src_data, src_linesize, *w, *h, pix_fmt,
231 /* copy mask to a newly allocated array */
232 *mask = av_malloc(*w * *h);
234 ret = AVERROR(ENOMEM);
235 av_image_copy_plane(*mask, *w, gray_data[0], gray_linesize[0], *w, *h);
238 av_free(src_data[0]);
239 av_free(gray_data[0]);
244 * Generate a scaled down image with half width, height, and intensity.
246 * This function not only scales down an image, but halves the value
247 * in each pixel too. The purpose of this is to produce a chroma
248 * filter image out of a luma filter image. The pixel values store the
249 * distance to the edge of the logo and halving the dimensions halves
250 * the distance. This function rounds up, because a downwards rounding
251 * error could cause the filter to fail, but an upwards rounding error
252 * will only cause a minor amount of excess blur in the chroma planes.
254 static void generate_half_size_image(const uint8_t *src_data, int src_linesize,
255 uint8_t *dst_data, int dst_linesize,
256 int src_w, int src_h,
261 /* Copy over the image data, using the average of 4 pixels for to
262 * calculate each downsampled pixel. */
263 for (y = 0; y < src_h/2; y++) {
264 for (x = 0; x < src_w/2; x++) {
265 /* Set the pixel if there exists a non-zero value in the
266 * source pixels, else clear it. */
267 dst_data[(y * dst_linesize) + x] =
268 src_data[((y << 1) * src_linesize) + (x << 1)] ||
269 src_data[((y << 1) * src_linesize) + (x << 1) + 1] ||
270 src_data[(((y << 1) + 1) * src_linesize) + (x << 1)] ||
271 src_data[(((y << 1) + 1) * src_linesize) + (x << 1) + 1];
272 dst_data[(y * dst_linesize) + x] = FFMIN(1, dst_data[(y * dst_linesize) + x]);
276 convert_mask_to_strength_mask(dst_data, dst_linesize,
277 src_w/2, src_h/2, 0, max_mask_size);
280 static av_cold int init(AVFilterContext *ctx)
282 RemovelogoContext *removelogo = ctx->priv;
286 int full_max_mask_size, half_max_mask_size;
288 if (!removelogo->filename) {
289 av_log(ctx, AV_LOG_ERROR, "The bitmap file name is mandatory\n");
290 return AVERROR(EINVAL);
293 /* Load our mask image. */
294 if ((ret = load_mask(&removelogo->full_mask_data, &w, &h, removelogo->filename, ctx)) < 0)
296 removelogo->mask_w = w;
297 removelogo->mask_h = h;
299 convert_mask_to_strength_mask(removelogo->full_mask_data, w, w, h,
300 16, &full_max_mask_size);
302 /* Create the scaled down mask image for the chroma planes. */
303 if (!(removelogo->half_mask_data = av_mallocz(w/2 * h/2)))
304 return AVERROR(ENOMEM);
305 generate_half_size_image(removelogo->full_mask_data, w,
306 removelogo->half_mask_data, w/2,
307 w, h, &half_max_mask_size);
309 removelogo->max_mask_size = FFMAX(full_max_mask_size, half_max_mask_size);
311 /* Create a circular mask for each size up to max_mask_size. When
312 the filter is applied, the mask size is determined on a pixel
313 by pixel basis, with pixels nearer the edge of the logo getting
314 smaller mask sizes. */
315 mask = (int ***)av_malloc(sizeof(int **) * (removelogo->max_mask_size + 1));
317 return AVERROR(ENOMEM);
319 for (a = 0; a <= removelogo->max_mask_size; a++) {
320 mask[a] = (int **)av_malloc(sizeof(int *) * ((a * 2) + 1));
322 return AVERROR(ENOMEM);
323 for (b = -a; b <= a; b++) {
324 mask[a][b + a] = (int *)av_malloc(sizeof(int) * ((a * 2) + 1));
326 return AVERROR(ENOMEM);
327 for (c = -a; c <= a; c++) {
328 if ((b * b) + (c * c) <= (a * a)) /* Circular 0/1 mask. */
329 mask[a][b + a][c + a] = 1;
331 mask[a][b + a][c + a] = 0;
335 removelogo->mask = mask;
337 /* Calculate our bounding rectangles, which determine in what
338 * region the logo resides for faster processing. */
339 ff_calculate_bounding_box(&removelogo->full_mask_bbox, removelogo->full_mask_data, w, w, h, 0);
340 ff_calculate_bounding_box(&removelogo->half_mask_bbox, removelogo->half_mask_data, w/2, w/2, h/2, 0);
342 #define SHOW_LOGO_INFO(mask_type) \
343 av_log(ctx, AV_LOG_VERBOSE, #mask_type " x1:%d x2:%d y1:%d y2:%d max_mask_size:%d\n", \
344 removelogo->mask_type##_mask_bbox.x1, removelogo->mask_type##_mask_bbox.x2, \
345 removelogo->mask_type##_mask_bbox.y1, removelogo->mask_type##_mask_bbox.y2, \
346 mask_type##_max_mask_size);
347 SHOW_LOGO_INFO(full);
348 SHOW_LOGO_INFO(half);
353 static int config_props_input(AVFilterLink *inlink)
355 AVFilterContext *ctx = inlink->dst;
356 RemovelogoContext *removelogo = ctx->priv;
358 if (inlink->w != removelogo->mask_w || inlink->h != removelogo->mask_h) {
359 av_log(ctx, AV_LOG_INFO,
360 "Mask image size %dx%d does not match with the input video size %dx%d\n",
361 removelogo->mask_w, removelogo->mask_h, inlink->w, inlink->h);
362 return AVERROR(EINVAL);
371 * It takes a pixel that is inside the mask and blurs it. It does so
372 * by finding the average of all the pixels within the mask and
373 * outside of the mask.
375 * @param mask_data the mask plane to use for averaging
376 * @param image_data the image plane to blur
377 * @param w width of the image
378 * @param h height of the image
379 * @param x x-coordinate of the pixel to blur
380 * @param y y-coordinate of the pixel to blur
382 static unsigned int blur_pixel(int ***mask,
383 const uint8_t *mask_data, int mask_linesize,
384 uint8_t *image_data, int image_linesize,
385 int w, int h, int x, int y)
387 /* Mask size tells how large a circle to use. The radius is about
388 * (slightly larger than) mask size. */
390 int start_posx, start_posy, end_posx, end_posy;
392 unsigned int accumulator = 0, divisor = 0;
393 /* What pixel we are reading out of the circular blur mask. */
394 const uint8_t *image_read_position;
395 /* What pixel we are reading out of the filter image. */
396 const uint8_t *mask_read_position;
398 /* Prepare our bounding rectangle and clip it if need be. */
399 mask_size = mask_data[y * mask_linesize + x];
400 start_posx = FFMAX(0, x - mask_size);
401 start_posy = FFMAX(0, y - mask_size);
402 end_posx = FFMIN(w - 1, x + mask_size);
403 end_posy = FFMIN(h - 1, y + mask_size);
405 image_read_position = image_data + image_linesize * start_posy + start_posx;
406 mask_read_position = mask_data + mask_linesize * start_posy + start_posx;
408 for (j = start_posy; j <= end_posy; j++) {
409 for (i = start_posx; i <= end_posx; i++) {
410 /* Check if this pixel is in the mask or not. Only use the
411 * pixel if it is not. */
412 if (!(*mask_read_position) && mask[mask_size][i - start_posx][j - start_posy]) {
413 accumulator += *image_read_position;
417 image_read_position++;
418 mask_read_position++;
421 image_read_position += (image_linesize - ((end_posx + 1) - start_posx));
422 mask_read_position += (mask_linesize - ((end_posx + 1) - start_posx));
425 /* If divisor is 0, it means that not a single pixel is outside of
426 the logo, so we have no data. Else we need to normalise the
427 data using the divisor. */
428 return divisor == 0 ? 255:
429 (accumulator + (divisor / 2)) / divisor; /* divide, taking into account average rounding error */
433 * Blur image plane using a mask.
435 * @param source The image to have it's logo removed.
436 * @param destination Where the output image will be stored.
437 * @param source_stride How far apart (in memory) two consecutive lines are.
438 * @param destination Same as source_stride, but for the destination image.
439 * @param width Width of the image. This is the same for source and destination.
440 * @param height Height of the image. This is the same for source and destination.
441 * @param is_image_direct If the image is direct, then source and destination are
442 * the same and we can save a lot of time by not copying pixels that
444 * @param filter The image that stores the distance to the edge of the logo for
446 * @param logo_start_x smallest x-coordinate that contains at least 1 logo pixel.
447 * @param logo_start_y smallest y-coordinate that contains at least 1 logo pixel.
448 * @param logo_end_x largest x-coordinate that contains at least 1 logo pixel.
449 * @param logo_end_y largest y-coordinate that contains at least 1 logo pixel.
451 * This function processes an entire plane. Pixels outside of the logo are copied
452 * to the output without change, and pixels inside the logo have the de-blurring
455 static void blur_image(int ***mask,
456 const uint8_t *src_data, int src_linesize,
457 uint8_t *dst_data, int dst_linesize,
458 const uint8_t *mask_data, int mask_linesize,
459 int w, int h, int direct,
464 const uint8_t *src_line;
467 av_image_copy_plane(dst_data, dst_linesize, src_data, src_linesize, w, h);
469 for (y = bbox->y1; y <= bbox->y2; y++) {
470 src_line = src_data + src_linesize * y;
471 dst_line = dst_data + dst_linesize * y;
473 for (x = bbox->x1; x <= bbox->x2; x++) {
474 if (mask_data[y * mask_linesize + x]) {
475 /* Only process if we are in the mask. */
476 dst_line[x] = blur_pixel(mask,
477 mask_data, mask_linesize,
478 dst_data, dst_linesize,
481 /* Else just copy the data. */
483 dst_line[x] = src_line[x];
489 static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
491 RemovelogoContext *removelogo = inlink->dst->priv;
492 AVFilterLink *outlink = inlink->dst->outputs[0];
496 if (av_frame_is_writable(inpicref)) {
498 outpicref = inpicref;
500 outpicref = ff_get_video_buffer(outlink, outlink->w, outlink->h);
502 av_frame_free(&inpicref);
503 return AVERROR(ENOMEM);
505 av_frame_copy_props(outpicref, inpicref);
508 blur_image(removelogo->mask,
509 inpicref ->data[0], inpicref ->linesize[0],
510 outpicref->data[0], outpicref->linesize[0],
511 removelogo->full_mask_data, inlink->w,
512 inlink->w, inlink->h, direct, &removelogo->full_mask_bbox);
513 blur_image(removelogo->mask,
514 inpicref ->data[1], inpicref ->linesize[1],
515 outpicref->data[1], outpicref->linesize[1],
516 removelogo->half_mask_data, inlink->w/2,
517 inlink->w/2, inlink->h/2, direct, &removelogo->half_mask_bbox);
518 blur_image(removelogo->mask,
519 inpicref ->data[2], inpicref ->linesize[2],
520 outpicref->data[2], outpicref->linesize[2],
521 removelogo->half_mask_data, inlink->w/2,
522 inlink->w/2, inlink->h/2, direct, &removelogo->half_mask_bbox);
525 av_frame_free(&inpicref);
527 return ff_filter_frame(outlink, outpicref);
530 static av_cold void uninit(AVFilterContext *ctx)
532 RemovelogoContext *removelogo = ctx->priv;
535 av_freep(&removelogo->full_mask_data);
536 av_freep(&removelogo->half_mask_data);
538 if (removelogo->mask) {
539 /* Loop through each mask. */
540 for (a = 0; a <= removelogo->max_mask_size; a++) {
541 /* Loop through each scanline in a mask. */
542 for (b = -a; b <= a; b++) {
543 av_free(removelogo->mask[a][b + a]); /* Free a scanline. */
545 av_free(removelogo->mask[a]);
547 /* Free the array of pointers pointing to the masks. */
548 av_freep(&removelogo->mask);
552 static const AVFilterPad removelogo_inputs[] = {
555 .type = AVMEDIA_TYPE_VIDEO,
556 .config_props = config_props_input,
557 .filter_frame = filter_frame,
562 static const AVFilterPad removelogo_outputs[] = {
565 .type = AVMEDIA_TYPE_VIDEO,
570 AVFilter avfilter_vf_removelogo = {
571 .name = "removelogo",
572 .description = NULL_IF_CONFIG_SMALL("Remove a TV logo based on a mask image."),
573 .priv_size = sizeof(RemovelogoContext),
576 .query_formats = query_formats,
577 .inputs = removelogo_inputs,
578 .outputs = removelogo_outputs,
579 .priv_class = &removelogo_class,
580 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,