[FFmpeg-devel] [PATCH] Implement cropdetect filter.
Stefano Sabatini
stefano.sabatini-lala
Fri Oct 8 17:19:47 CEST 2010
---
configure | 1 +
doc/filters.texi | 36 +++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_cropdetect.c | 215 +++++++++++++++++++++++++++++++++++++++++++
5 files changed, 254 insertions(+), 0 deletions(-)
create mode 100644 libavfilter/vf_cropdetect.c
diff --git a/configure b/configure
index 29b07f3..f04c34a 100755
--- a/configure
+++ b/configure
@@ -1399,6 +1399,7 @@ udp_protocol_deps="network"
# filters
blackframe_filter_deps="gpl"
+cropdetect_filter_deps="gpl"
frei0r_filter_deps="frei0r dlopen strtok_r"
ocv_smooth_filter_deps="libopencv"
yadif_filter_deps="gpl"
diff --git a/doc/filters.texi b/doc/filters.texi
index e4c1851..c38aaf8 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -190,6 +190,42 @@ crop=in_w-100:in_h-100:100:100
"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
@end example
+ at section cropdetect
+
+Auto-detect crop size.
+
+Calculate necessary cropping parameters and prints the recommended
+parameters through the logging system. The detected dimensions
+correspond to the non-black area of the input video.
+
+It accepts the syntax:
+ at example
+cropdetect[=@var{limit}:@var{round}[:@var{reset}]]
+ at end example
+
+ at table @option
+
+ at item limit
+Threshold, which can be optionally specified from nothing (0) to
+everything (255), defaults to 24.
+
+ at item round
+Value which the width/height should be divisible by, defaults to
+16. The offset is automatically adjusted to center the video. Use 2 to
+get only even dimensions (needed for 4:2:2 video). 16 is best when
+encoding to most video codecs.
+
+ at item reset
+
+Counter that determines after how many frames cropdetect will reset
+the previously detected largest video area and start over to detect
+the current optimal crop area. Default to 0.
+
+This can be useful when channel logos distort the video area. 0
+indicates never reset and return the largest area encountered during
+playback.
+ at end table
+
@section drawbox
Draw a colored box on the input image.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 74e55bb..b1fac8e 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -23,6 +23,7 @@ OBJS-$(CONFIG_ANULLSINK_FILTER) += asink_anullsink.o
OBJS-$(CONFIG_ASPECT_FILTER) += vf_aspect.o
OBJS-$(CONFIG_BLACKFRAME_FILTER) += vf_blackframe.o
OBJS-$(CONFIG_CROP_FILTER) += vf_crop.o
+OBJS-$(CONFIG_CROPDETECT_FILTER) += vf_cropdetect.o
OBJS-$(CONFIG_DRAWBOX_FILTER) += vf_drawbox.o
OBJS-$(CONFIG_FIFO_FILTER) += vf_fifo.o
OBJS-$(CONFIG_FORMAT_FILTER) += vf_format.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index c5da648..aee3a11 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -43,6 +43,7 @@ void avfilter_register_all(void)
REGISTER_FILTER (ASPECT, aspect, vf);
REGISTER_FILTER (BLACKFRAME, blackframe, vf);
REGISTER_FILTER (CROP, crop, vf);
+ REGISTER_FILTER (CROPDETECT, cropdetect, vf);
REGISTER_FILTER (DRAWBOX, drawbox, vf);
REGISTER_FILTER (FIFO, fifo, vf);
REGISTER_FILTER (FORMAT, format, vf);
diff --git a/libavfilter/vf_cropdetect.c b/libavfilter/vf_cropdetect.c
new file mode 100644
index 0000000..7fb0474
--- /dev/null
+++ b/libavfilter/vf_cropdetect.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright (C) 2002 A'rpi
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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
+ * border detection filter
+ * Ported from MPlayer libmpcodecs/vf_cropdetect.c.
+ */
+
+#include "libavcore/imgutils.h"
+#include "avfilter.h"
+
+typedef struct {
+ int x1, y1, x2, y2;
+ int limit;
+ int round;
+ int reset_count;
+ int frame_nb;
+ int max_pixsteps[4];
+} CropDetectContext;
+
+
+static int query_formats(AVFilterContext *ctx)
+{
+ static const enum PixelFormat pix_fmts[] = {
+ PIX_FMT_YUV420P, PIX_FMT_YUVJ420P,
+ PIX_FMT_YUV422P, PIX_FMT_YUVJ422P,
+ PIX_FMT_YUV444P, PIX_FMT_YUVJ444P,
+ PIX_FMT_YUV411P, PIX_FMT_GRAY8,
+ PIX_FMT_NV12, PIX_FMT_NV21,
+ PIX_FMT_NONE
+ };
+
+ avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
+ return 0;
+}
+
+static int checkline(void *ctx, unsigned char *src, int stride, int len, int bpp)
+{
+ int total = 0;
+ int div = len;
+
+ switch (bpp) {
+ case 1:
+ while (--len >= 0) {
+ total += src[0];
+ src += stride;
+ }
+ break;
+ case 3:
+ case 4:
+ while (--len >= 0) {
+ total += src[0] + src[1] + src[2];
+ src += stride;
+ }
+ div *= 3;
+ break;
+ }
+ total /= div;
+
+ av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
+ return total;
+}
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+ CropDetectContext *cd = ctx->priv;
+
+ cd->limit = 24;
+ cd->round = 0;
+ cd->reset_count = 0;
+ cd->frame_nb = -2;
+
+ if (args)
+ sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
+
+ av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
+ cd->limit, cd->round, cd->reset_count);
+
+ return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ CropDetectContext *cd = ctx->priv;
+
+ av_image_fill_max_pixsteps(cd->max_pixsteps, NULL,
+ &av_pix_fmt_descriptors[inlink->format]);
+
+ cd->x1 = inlink->w - 1;
+ cd->y1 = inlink->h - 1;
+ cd->x2 = 0;
+ cd->y2 = 0;
+
+ return 0;
+}
+
+static void end_frame(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ CropDetectContext *cd = ctx->priv;
+ AVFilterBufferRef *picref = inlink->cur_buf;
+ int bpp = cd->max_pixsteps[0];
+ int w, h, x, y, shrink_by;
+
+ // ignore first 2 frames - they may be empty
+ if (++cd->frame_nb > 0) {
+ // Reset the crop area every reset_count frames, if reset_count is > 0
+ if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
+ cd->x1 = picref->video->w-1;
+ cd->y1 = picref->video->h-1;
+ cd->x2 = 0;
+ cd->y2 = 0;
+ cd->frame_nb = 1;
+ }
+
+ for (y = 0; y < cd->y1; y++) {
+ if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
+ cd->y1 = y;
+ break;
+ }
+ }
+
+ for (y = picref->video->h-1; y > cd->y2; y--) {
+ if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
+ cd->y2 = y;
+ break;
+ }
+ }
+
+ for (y = 0; y < cd->x1; y++) {
+ if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
+ cd->x1 = y;
+ break;
+ }
+ }
+
+ for (y = picref->video->w-1; y > cd->x2; y--) {
+ if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
+ cd->x2 = y;
+ break;
+ }
+ }
+
+ // round x and y (up), important for yuv colorspaces
+ // make sure they stay rounded!
+ x = (cd->x1+1)&(~1);
+ y = (cd->y1+1)&(~1);
+
+ w = cd->x2 - x + 1;
+ h = cd->y2 - y + 1;
+
+ // w and h must be divisible by 2 as well because of yuv
+ // colorspace problems.
+ if (cd->round <= 1)
+ cd->round = 16;
+ if (cd->round % 2)
+ cd->round *= 2;
+
+ shrink_by = w % cd->round;
+ w -= shrink_by;
+ x += (shrink_by / 2 + 1) & ~1;
+
+ shrink_by = h % cd->round;
+ h -= shrink_by;
+ y += (shrink_by / 2 + 1) & ~1;
+
+ av_log(ctx, AV_LOG_INFO,
+ "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pos:%"PRId64" pts:%f crop=%d:%d:%d:%d\n",
+ cd->x1, cd->x2, cd->y1, cd->y2, w, h, x, y, picref->pos,
+ picref->pts == AV_NOPTS_VALUE ? -1 : (double)picref->pts / AV_TIME_BASE,
+ w, h, x, y);
+ }
+
+ avfilter_end_frame(inlink->dst->outputs[0]);
+}
+
+AVFilter avfilter_vf_cropdetect = {
+ .name = "cropdetect",
+ .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
+
+ .priv_size = sizeof(CropDetectContext),
+ .init = init,
+
+ .query_formats = query_formats,
+
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .config_props = config_input,
+ .get_video_buffer = avfilter_null_get_video_buffer,
+ .start_frame = avfilter_null_start_frame,
+ .end_frame = end_frame, },
+ { .name = NULL}},
+
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO },
+ { .name = NULL}},
+};
--
1.7.1
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