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.

Changelog

@@ -14,6 +14,7 @@ version next:
 - blackdetect filter
 - libutvideo encoder wrapper (--enable-libutvideo)
 - swapuv filter
+- bbox filter
 
 
 version 0.10:

doc/filters.texi

@@ -761,6 +761,16 @@ video, use the command:
 ass=sub.ass
 @end example
 
+@section bbox
+
+Compute the bounding box for the non-black pixels in the input frame
+luminance plane.
+
+This filter computes the bounding box containing all the pixels with a
+luminance value greater than the minimum allowed value.
+The parameters describing the bounding box are printed on the filter
+log.
+
 @section blackdetect
 
 Detect video intervals that are (almost) completely black. Can be

libavfilter/Makefile

@@ -48,6 +48,7 @@ OBJS-$(CONFIG_ABUFFERSINK_FILTER)            += sink_buffer.o
 OBJS-$(CONFIG_ANULLSINK_FILTER)              += asink_anullsink.o
 
 OBJS-$(CONFIG_ASS_FILTER)                    += vf_ass.o
+OBJS-$(CONFIG_BBOX_FILTER)                   += bbox.o vf_bbox.o
 OBJS-$(CONFIG_BLACKDETECT_FILTER)            += vf_blackdetect.o
 OBJS-$(CONFIG_BLACKFRAME_FILTER)             += vf_blackframe.o
 OBJS-$(CONFIG_BOXBLUR_FILTER)                += vf_boxblur.o

libavfilter/allfilters.c

@@ -56,6 +56,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (ANULLSINK,   anullsink,   asink);
 
     REGISTER_FILTER (ASS,         ass,  vf);
+    REGISTER_FILTER (BBOX,        bbox,        vf);
     REGISTER_FILTER (BLACKDETECT, blackdetect, vf);
     REGISTER_FILTER (BLACKFRAME,  blackframe,  vf);
     REGISTER_FILTER (BOXBLUR,     boxblur,     vf);

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;
+}

libavfilter/bbox.h

@@ -0,0 +1,44 @@
+/*
+ * 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
+ */
+
+#ifndef AVFILTER_BBOX_H
+#define AVFILTER_BBOX_H
+
+#include <stdint.h>
+
+typedef struct {
+    int x1, x2, y1, y2;
+} FFBoundingBox;
+
+/**
+ * Calculate the smallest rectangle that will encompass the
+ * region with values > min_val.
+ *
+ * @param bbox bounding box structure which is updated with the found values.
+ *             If no pixels could be found with value > min_val, the
+ *             structure is not modified.
+ * @return 1 in case at least one pixel with value > min_val was found,
+ *         0 otherwise
+ */
+int ff_calculate_bounding_box(FFBoundingBox *bbox,
+                              const uint8_t *data, int linesize,
+                              int w, int h, int min_val);
+
+#endif /* AVFILTER_BBOX_H */

libavfilter/version.h

@@ -29,8 +29,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR 64
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR 65
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_bbox.c

@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2012 Stefano Sabatini
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * bounding box detection filter
+ */
+
+#include "libavutil/pixdesc.h"
+#include "libavutil/timestamp.h"
+#include "avfilter.h"
+#include "bbox.h"
+
+typedef struct {
+    unsigned int frame;
+    int vsub, hsub;
+} BBoxContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    BBoxContext *bbox = ctx->priv;
+    bbox->frame = 0;
+    return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum PixelFormat pix_fmts[] = {
+        PIX_FMT_YUV420P,
+        PIX_FMT_YUV444P,
+        PIX_FMT_YUV440P,
+        PIX_FMT_YUV422P,
+        PIX_FMT_YUV411P,
+        PIX_FMT_NONE,
+    };
+
+    avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
+    return 0;
+}
+
+static void end_frame(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    BBoxContext *bbox = ctx->priv;
+    AVFilterBufferRef *picref = inlink->cur_buf;
+    FFBoundingBox box;
+    int has_bbox, w, h;
+
+    has_bbox =
+        ff_calculate_bounding_box(&box,
+                                  picref->data[0], picref->linesize[0],
+                                  inlink->w, inlink->h, 16);
+    w = box.x2 - box.x1 + 1;
+    h = box.y2 - box.y1 + 1;
+
+    av_log(ctx, AV_LOG_INFO,
+           "n:%d pts:%s pts_time:%s", bbox->frame,
+           av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base));
+
+    if (has_bbox) {
+        av_log(ctx, AV_LOG_INFO,
+               "x1:%d x2:%d y1:%d y2:%d w:%d h:%d"
+               " crop=%d:%d:%d:%d drawbox=%d:%d:%d:%d",
+               box.x1, box.x2, box.y1, box.y2, w, h,
+               w, h, box.x1, box.y1,    /* crop params */
+               box.x1, box.y1, w, h);   /* drawbox params */
+    }
+    av_log(ctx, AV_LOG_INFO, "\n");
+
+    bbox->frame++;
+    avfilter_end_frame(inlink->dst->outputs[0]);
+}
+
+AVFilter avfilter_vf_bbox = {
+    .name          = "bbox",
+    .description   = NULL_IF_CONFIG_SMALL("Compute bounding box for each frame."),
+    .priv_size     = sizeof(BBoxContext),
+    .query_formats = query_formats,
+    .init          = init,
+
+    .inputs = (const AVFilterPad[]) {
+        { .name             = "default",
+          .type             = AVMEDIA_TYPE_VIDEO,
+          .get_video_buffer = avfilter_null_get_video_buffer,
+          .start_frame      = avfilter_null_start_frame,
+          .end_frame        = end_frame,
+          .min_perms        = AV_PERM_READ, },
+        { .name = NULL }
+    },
+
+    .outputs = (const AVFilterPad[]) {
+        { .name             = "default",
+          .type             = AVMEDIA_TYPE_VIDEO },
+        { .name = NULL }
+    },
+};