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

["Jörg Habenicht via ffmpeg-devel" <ffmpeg-devel@ffmpeg.org>]

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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