lavfi: add bbox filter

Also add bbox.h and bbox.c files, based on the remove-logo filter by
Robert Edele. These files are useful for sharing code with the pending
removelogo port.

1 files changed, 75 insertions, 0 deletions

diff --git a/libavfilter/bbox.c b/libavfilter/bbox.c
new file mode 100644
index 0000000000..c29c75873f
--- /dev/null
+++ b/libavfilter/bbox.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2005 Robert Edele <yartrebo@earthlink.net>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "bbox.h"
+
+int ff_calculate_bounding_box(FFBoundingBox *bbox,
+                              const uint8_t *data, int linesize, int w, int h,
+                              int min_val)
+{
+    int x, y;
+    int start_x;
+    int start_y;
+    int end_x = w - 1;
+    int end_y = h - 1;
+    const uint8_t *line;
+
+    /* left bound */
+    for (start_x = 0; start_x < w; start_x++)
+        for (y = 0; y < h; y++)
+            if ((data[y * linesize + start_x] > min_val))
+                goto outl;
+outl:
+    if (start_x == w) /* no points found */
+        return 0;
+
+    /* right bound */
+    for (end_x = w - 1; end_x >= start_x; end_x--)
+        for (y = 0; y < h; y++)
+            if ((data[y * linesize + end_x] > min_val))
+                goto outr;
+outr:
+
+    /* top bound */
+    line = data;
+    for (start_y = 0; start_y < h; start_y++) {
+        for (x = 0; x < w; x++)
+            if (line[x] > min_val)
+                goto outt;
+        line += linesize;
+    }
+outt:
+
+    /* bottom bound */
+    line = data + (h-1)*linesize;
+    for (end_y = h - 1; end_y >= start_y; end_y--) {
+        for (x = 0; x < w; x++)
+            if (line[x] > min_val)
+                goto outb;
+        line -= linesize;
+    }
+outb:
+
+    bbox->x1 = start_x;
+    bbox->y1 = start_y;
+    bbox->x2 = end_x;
+    bbox->y2 = end_y;
+    return 1;
+}