avfilter/vf_fillborders: add another mode

doc/filters.texi

@@ -12280,6 +12280,9 @@ fill pixels using wrapping
 
 @item fade
 fade pixels to constant value
+
+@item margins
+fill pixels at top and bottom with weighted averages pixels near borders
 @end table
 
 Default is @var{smear}.

libavfilter/vf_fillborders.c

@@ -32,7 +32,7 @@
 enum { Y, U, V, A };
 enum { R, G, B };
 
-enum FillMode { FM_SMEAR, FM_MIRROR, FM_FIXED, FM_REFLECT, FM_WRAP, FM_FADE, FM_NB_MODES };
+enum FillMode { FM_SMEAR, FM_MIRROR, FM_FIXED, FM_REFLECT, FM_WRAP, FM_FADE, FM_MARGINS, FM_NB_MODES };
 
 typedef struct Borders {
     int left, right, top, bottom;
@@ -495,6 +495,99 @@ static void fade_borders16(FillBordersContext *s, AVFrame *frame)
     }
 }
 
+static void margins_borders8(FillBordersContext *s, AVFrame *frame)
+{
+    for (int p = 0; p < s->nb_planes; p++) {
+        uint8_t *ptr = (uint8_t *)frame->data[p];
+        const int linesize = frame->linesize[p];
+        const int left = s->borders[p].left;
+        const int right = s->borders[p].right;
+        const int top = s->borders[p].top;
+        const int bottom = s->borders[p].bottom;
+        const int width = s->planewidth[p];
+        const int height = s->planeheight[p];
+
+        for (int y = top; y < height - bottom; y++) {
+            memset(ptr + linesize * y, ptr[linesize * y + left], left);
+            memset(ptr + linesize * y + width - right, (ptr + linesize * y + width - right)[-1], right);
+        }
+
+        for (int y = top - 1; y >= 0; y--) {
+            ptr[linesize * y] = ptr[linesize * (y + 1)];
+            memcpy(ptr + linesize * y + width - 8, ptr + linesize * (y + 1) + width - 8, 8);
+
+            for (int x = 1; x < width - 8; x++) {
+                int prev = ptr[linesize * (y + 1) + x - 1];
+                int cur  = ptr[linesize * (y + 1) + x];
+                int next = ptr[linesize * (y + 1) + x + 1];
+
+                ptr[linesize * y + x] = (3 * prev + 2 * cur + 3 * next + 4) >> 3;
+            }
+        }
+
+        for (int y = height - bottom; y < height; y++) {
+            ptr[linesize * y] = ptr[linesize * (y - 1)];
+            memcpy(ptr + linesize * y + width - 8, ptr + linesize * (y - 1) + width - 8, 8);
+
+            for (int x = 1; x < width - 8; x++) {
+                int prev = ptr[linesize * (y - 1) + x - 1];
+                int cur  = ptr[linesize * (y - 1) + x];
+                int next = ptr[linesize * (y - 1) + x + 1];
+
+                ptr[linesize * y + x] = (3 * prev + 2 * cur + 3 * next + 4) >> 3;
+            }
+        }
+    }
+}
+
+static void margins_borders16(FillBordersContext *s, AVFrame *frame)
+{
+    for (int p = 0; p < s->nb_planes; p++) {
+        uint16_t *ptr = (uint16_t *)frame->data[p];
+        const int linesize = frame->linesize[p] / 2;
+        const int left = s->borders[p].left;
+        const int right = s->borders[p].right;
+        const int top = s->borders[p].top;
+        const int bottom = s->borders[p].bottom;
+        const int width = s->planewidth[p];
+        const int height = s->planeheight[p];
+
+        for (int y = top; y < height - bottom; y++) {
+            for (int x = 0; x < left; x++)
+                ptr[linesize * y + x] = ptr[linesize * y + left];
+
+            for (int x = 0; x < right; x++)
+                ptr[linesize * y + width - right + x] = ptr[linesize * y + width - right - 1];
+        }
+
+        for (int y = top - 1; y >= 0; y--) {
+            ptr[linesize * y] = ptr[linesize * (y + 1)];
+            memcpy(ptr + linesize * y + width - 8, ptr + linesize * (y + 1) + width - 8, 16);
+
+            for (int x = 1; x < width - 8; x++) {
+                int prev = ptr[linesize * (y + 1) + x - 1];
+                int cur  = ptr[linesize * (y + 1) + x];
+                int next = ptr[linesize * (y + 1) + x + 1];
+
+                ptr[linesize * y + x] = (3 * prev + 2 * cur + 3 * next + 4) >> 3;
+            }
+        }
+
+        for (int y = height - bottom; y < height; y++) {
+            ptr[linesize * y] = ptr[linesize * (y - 1)];
+            memcpy(ptr + linesize * y + width - 8, ptr + linesize * (y - 1) + width - 8, 16);
+
+            for (int x = 1; x < width - 8; x++) {
+                int prev = ptr[linesize * (y - 1) + x - 1];
+                int cur  = ptr[linesize * (y - 1) + x];
+                int next = ptr[linesize * (y - 1) + x + 1];
+
+                ptr[linesize * y + x] = (3 * prev + 2 * cur + 3 * next + 4) >> 3;
+            }
+        }
+    }
+}
+
 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
 {
     FillBordersContext *s = inlink->dst->priv;
@@ -554,6 +647,7 @@ static int config_input(AVFilterLink *inlink)
     case FM_REFLECT:s->fillborders = s->depth <= 8 ? reflect_borders8: reflect_borders16;break;
     case FM_WRAP:   s->fillborders = s->depth <= 8 ? wrap_borders8   : wrap_borders16;   break;
     case FM_FADE:   s->fillborders = s->depth <= 8 ? fade_borders8   : fade_borders16;   break;
+    case FM_MARGINS:s->fillborders = s->depth <= 8 ? margins_borders8: margins_borders16;break;
     default: av_assert0(0);
     }
 
@@ -603,6 +697,7 @@ static const AVOption fillborders_options[] = {
         { "reflect",NULL, 0, AV_OPT_TYPE_CONST, {.i64=FM_REFLECT},0, 0, FLAGS, "mode" },
         { "wrap",   NULL, 0, AV_OPT_TYPE_CONST, {.i64=FM_WRAP},   0, 0, FLAGS, "mode" },
         { "fade",   NULL, 0, AV_OPT_TYPE_CONST, {.i64=FM_FADE},   0, 0, FLAGS, "mode" },
+        { "margins",NULL, 0, AV_OPT_TYPE_CONST, {.i64=FM_MARGINS},0, 0, FLAGS, "mode" },
     { "color",  "set the color for the fixed/fade mode", OFFSET(rgba_color), AV_OPT_TYPE_COLOR, {.str = "black"}, .flags = FLAGS },
     { NULL }
 };