[FFmpeg-devel] [PATCH 0/3] Patch to create a circular delogo area

[FFmpeg-devel] [PATCH 0/3] Patch to create a circular delogo area

[Jörg Habenicht via ffmpeg-devel]

Dear list,

sorry for the previous posting. I noticed the lines got mangled. So here
is a new try to get the patches right.


Old text:
I made a patch for the delogo filter. With this I can create a circular or
elliptic zone to apply the delogo algorithm. The borders are defined with
x,y,w,h parameter just like the rectangular area definition. To become
circular I added an additional parameter 'r'=0/1 defaulting to '0' i.e.
rectangular area definition.

I added a large comment to the function body describing the calculation
of the ellipse. Hope you don't mind.
The patch has been tested with 'make fate-rsync fate' and applies
clean to the master branch, commit 957eb2323a924aa0b148927889eae581185c367b .

Please have a look.

best regards
Jörg


Jörg Habenicht (3):
  avfilter/delogo: add parameter to switch on circular delogo
  avfilter/delogo: added circular delogo algorithm description
  avfilter/delogo: added the circular delogo algorithm

 libavfilter/vf_delogo.c | 59 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 5 deletions(-)

--
2.45.3

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[FFmpeg-devel] [PATCH 1/3] avfilter/delogo: add parameter to switch on circular delogo

[Jörg Habenicht via ffmpeg-devel]

Add a parameter (boolean) r to switch the area from
rectangular (r=0) to circular(r=1) delogo.

Signed-off-by: Jörg Habenicht <j.habenicht@gmx.de>
---
 libavfilter/vf_delogo.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libavfilter/vf_delogo.c b/libavfilter/vf_delogo.c
index bfbf8e6f4c..7641c3b483 100644
--- a/libavfilter/vf_delogo.c
+++ b/libavfilter/vf_delogo.c
@@ -195,7 +195,7 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,

 typedef struct DelogoContext {
     const AVClass *class;
-    int x, y, w, h, band, show;
+    int x, y, w, h, band, show, round;
     char *x_expr, *y_expr, *w_expr, *h_expr;
     AVExpr *x_pexpr, *y_pexpr, *w_pexpr, *h_pexpr;
     double var_values[VAR_VARS_NB];
@@ -209,6 +209,7 @@ static const AVOption delogo_options[]= {
     { "y",    "set logo y position",       OFFSET(y_expr),    AV_OPT_TYPE_STRING, { .str = "-1" }, 0, 0, FLAGS },
     { "w",    "set logo width",            OFFSET(w_expr),    AV_OPT_TYPE_STRING, { .str = "-1" }, 0, 0, FLAGS },
     { "h",    "set logo height",           OFFSET(h_expr),    AV_OPT_TYPE_STRING, { .str = "-1" }, 0, 0, FLAGS },
+    { "r",    "logo is round/ellipse",     OFFSET(round),     AV_OPT_TYPE_BOOL,   { .i64 =  0 },   0, 1, FLAGS },
     { "show", "show delogo area",          OFFSET(show),      AV_OPT_TYPE_BOOL,   { .i64 =  0 },   0, 1, FLAGS },
     { NULL }
 };
@@ -259,8 +260,8 @@ static av_cold int init(AVFilterContext *ctx)

     s->band = 1;

-    av_log(ctx, AV_LOG_VERBOSE, "x:%d y:%d, w:%d h:%d band:%d show:%d\n",
-           s->x, s->y, s->w, s->h, s->band, s->show);
+    av_log(ctx, AV_LOG_VERBOSE, "x:%d y:%d, w:%d h:%d band:%d round:%d show:%d\n",
+           s->x, s->y, s->w, s->h, s->band, s->round, s->show);

     s->w += s->band*2;
     s->h += s->band*2;
--
2.45.3

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[FFmpeg-devel] [PATCH 2/3] avfilter/delogo: added circular delogo algorithm description

[Jörg Habenicht via ffmpeg-devel]

Added a description of the elliptic formed delogo algorithm. Placed it
outside the doxygen function comment.

Signed-off-by: Jörg Habenicht <j.habenicht@gmx.de>
---
 libavfilter/vf_delogo.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/libavfilter/vf_delogo.c b/libavfilter/vf_delogo.c
index 7641c3b483..ea741e2700 100644
--- a/libavfilter/vf_delogo.c
+++ b/libavfilter/vf_delogo.c
@@ -100,6 +100,30 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
                          int logo_x, int logo_y, int logo_w, int logo_h,
                          unsigned int band, int show, int direct)
 {
+    /* Round area algorithm description:
+     *
+     * logo_x, logo_y, logo_w and logo_h define the boundaries of the
+     * ellipse. In the ellipse formula x^2 / a^2 + y^2 / b^2 = 1 let
+     * a = logo_w/2, b = logo_h/2 and the center of the ellipse
+     * (0,0) = (logo_x + a, logo_y + b).
+     * Let the picture dimensions (px,py,pw,ph) := function API(x,y,w,h).
+     * A point of the picture is transformed into the ellipse coordinates
+     * by using x = px - (logo_x + a), y = py - (logo_y +b).
+     *
+     * A point is inside the ellipse if x^2 / a^2 + y^2 / b^2 <= 1
+     * <=> (x + logo_x)^2 / (logo_w / 2)^2
+     *     + (y + logo_y)^2 / (logo_h / 2)^2 <= 1
+     * <=> (px - logo_x - a + logo_x)^2 / (logo_w / 2)^2
+     *     + (py - logo_y - b + logo_y)^2 / (logo_h / 2)^2 <= 1
+     * <=> (px - a)^2 / (logo_w / 2)^2
+     *     + (py - b)^2 / (logo_h / 2)^2 <= 1
+     * <=> ((px - a) / (logo_w / 2))^2
+     *     + ((py - b) / (logo_h / 2))^2 <= 1
+     *
+     * px is later defined x, py defined y.
+     * logo_w is later defined logo_w2, logo_h defined logo_h2.
+     */
+
     int x, y;
     uint64_t interp, weightl, weightr, weightt, weightb, weight;
     uint8_t *xdst, *xsrc;
--
2.45.3

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[FFmpeg-devel] [PATCH 3/3] avfilter/delogo: added the circular delogo algorithm

[Jörg Habenicht via ffmpeg-devel]

Use the corrected x,y,w,h values with boundaries and clipping to
calculate the points inside the ellipse.

Signed-off-by: Jörg Habenicht <j.habenicht@gmx.de>
---
 libavfilter/vf_delogo.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/libavfilter/vf_delogo.c b/libavfilter/vf_delogo.c
index ea741e2700..fcf14d3e4f 100644
--- a/libavfilter/vf_delogo.c
+++ b/libavfilter/vf_delogo.c
@@ -90,6 +90,7 @@ static int set_expr(AVExpr **pexpr, const char *expr, const char *option, void *
  * @param logo_w width of the logo
  * @param logo_h height of the logo
  * @param band   the size of the band around the processed area
+ * @param round  whether delogo is applied to a rectangular or round area
  * @param show   show a rectangle around the processed area, useful for
  *               parameters tweaking
  * @param direct if non-zero perform in-place processing
@@ -98,7 +99,7 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
                          uint8_t *src, int src_linesize,
                          int w, int h, AVRational sar,
                          int logo_x, int logo_y, int logo_w, int logo_h,
-                         unsigned int band, int show, int direct)
+                         unsigned int band, int round, int show, int direct)
 {
     /* Round area algorithm description:
      *
@@ -132,6 +133,7 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
     unsigned int left_sample, right_sample;
     int xclipl, xclipr, yclipt, yclipb;
     int logo_x1, logo_x2, logo_y1, logo_y2;
+    double a, b, logo_w2, logo_h2;

     xclipl = FFMAX(-logo_x, 0);
     xclipr = FFMAX(logo_x+logo_w-w, 0);
@@ -147,6 +149,13 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
     topright = src+logo_y1 * src_linesize+logo_x2;
     botleft  = src+logo_y2 * src_linesize+logo_x1;

+    if (round) {
+        logo_w2 = (logo_x2 - logo_x1) / 2.0;
+        logo_h2 = (logo_y2 - logo_y1) / 2.0;
+        a = logo_x1 + logo_w2;
+        b = logo_y1 + logo_h2;
+    }
+
     if (!direct)
         av_image_copy_plane(dst, dst_linesize, src, src_linesize, w, h);

@@ -171,6 +180,21 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
                 continue;
             }

+            if (round) {
+                double xf, yf;
+                /* Evaluate if x,y is inside the ellipse, else continue
+                 * This is the calculation
+                 *      (px - a)^2 / (logo_w / 2)^2 +
+                 *      (py - b)^2 / (logo_h / 2)^2 <= 1
+                 */
+                xf = ((double)x - a) / logo_w2;
+                xf *= xf;
+                yf = ((double)y - b) / logo_h2;
+                yf *= yf;
+                if (xf + yf > 1.0)
+                    continue;
+            }
+
             /* Weighted interpolation based on relative distances, taking SAR into account */
             weightl = (uint64_t)              (logo_x2-x) * (y-logo_y1) * (logo_y2-y) * sar.den;
             weightr = (uint64_t)(x-logo_x1)               * (y-logo_y1) * (logo_y2-y) * sar.den;
@@ -388,7 +412,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
                      AV_CEIL_RSHIFT(s->w + (s->x & ((1<<hsub)-1)), hsub),
                      AV_CEIL_RSHIFT(s->h + (s->y & ((1<<vsub)-1)), vsub),
                      s->band>>FFMIN(hsub, vsub),
-                     s->show, direct);
+                     s->round, s->show, direct);
     }

     if (!direct)
--
2.45.3

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