[FFmpeg-devel] [PATCH] lavfi: add bbox filter

Nicolas George nicolas.george at normalesup.org
Sun Mar 11 10:02:14 CET 2012


Le duodi 22 ventôse, an CCXX, Stefano Sabatini a écrit :
> Also add bbox.h and bbox.c files, based on the remove-logo filter by
> Robert Edele.

Do you consider the code rewritten/trivial enough not to require Robert's
approval for the licence change?

> 
> These files are useful for sharing code with the pending removelogo port.
> ---
>  doc/filters.texi         |    9 +++
>  libavfilter/Makefile     |    1 +
>  libavfilter/allfilters.c |    1 +
>  libavfilter/bbox.c       |   70 ++++++++++++++++++++++++++
>  libavfilter/bbox.h       |   42 ++++++++++++++++
>  libavfilter/vf_bbox.c    |  122 ++++++++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 245 insertions(+), 0 deletions(-)
>  create mode 100644 libavfilter/bbox.c
>  create mode 100644 libavfilter/bbox.h
>  create mode 100644 libavfilter/vf_bbox.c
> 
> diff --git a/doc/filters.texi b/doc/filters.texi
> index b13d5f5..62783c0 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -761,6 +761,15 @@ video, use the command:
>  ass=sub.ass
>  @end example
>  
> + at section bbox
> +
> +Compute the bounding box for each input frame.
> +
> +This filter computes the bounding box containing all the pixels with a
> +non-null value. The bounding box is computed for each plane in the
> +input image, and the corresponding parameters are print on the filter
> +log.

"are printed".

Also, we will need to decide something someday for those filters that print
useful information, to allow to use them reliably in scripts.

> +
>  @section blackdetect
>  
>  Detect video intervals that are (almost) completely black. Can be
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index e9c9a4b..6a9a3ad 100644
> --- a/libavfilter/Makefile
> +++ b/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
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index f0a7f8b..6972271 100644
> --- a/libavfilter/allfilters.c
> +++ b/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);
> diff --git a/libavfilter/bbox.c b/libavfilter/bbox.c
> new file mode 100644
> index 0000000..a43d974
> --- /dev/null
> +++ b/libavfilter/bbox.c
> @@ -0,0 +1,70 @@
> +/*
> + * Copyright (c) 2005 Robert Edele <yartrebo at 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"
> +
> +void calculate_bounding_rectangle(BoundingBox *bbox,
> +                                  const uint8_t *data, int linesize, int w, int h,
> +                                  int min_val)

ff_ prefix missing.

> +{
> +    int x, y;
> +    int start_x;
> +    int start_y;
> +    int end_x = w - 1;
> +    int end_y = h - 1;
> +    int pixel_found;
> +
> +    /* left bound */
> +    for (pixel_found = 0, start_x = 0; start_x < w; start_x++) {
> +        for (y = 0; y < h; y++)
> +            pixel_found |= (data[y * linesize + start_x] > min_val);

Did you check that the compiler is smart enough to optimize the
multiplication away? If not, keeping and updating a pointer is easy an
efficient.

> +        if (pixel_found)
> +            break;
> +    }

A goto to break the two loops at once may be more readable.

> +
> +    /* right bound */
> +    for (pixel_found = 0, end_x = w - 1; end_x >= start_x; end_x--) {
> +        for (y = 0; y < h; y++)
> +            pixel_found |= (data[y * linesize + end_x] > min_val);
> +        if (pixel_found)
> +            break;
> +    }
> +
> +    /* top bound */
> +    for (pixel_found = 0, start_y = 0; start_y < h; start_y++) {
> +        for (x = 0; x < w; x++)
> +            pixel_found |= (data[start_y * linesize + x] > min_val);
> +        if (pixel_found)
> +            break;
> +    }
> +
> +    /* bottom bound */
> +    for (pixel_found = 0, end_y = h - 1; end_y >= start_y; end_y--) {
> +        for (x = 0; x < w; x++)
> +            pixel_found |= (data[end_y * linesize + x] > min_val);
> +        if (pixel_found)
> +            break;
> +    }
> +
> +    bbox->x1 = start_x;
> +    bbox->y1 = start_y;
> +    bbox->x2 = end_x;
> +    bbox->y2 = end_y;
> +}
> diff --git a/libavfilter/bbox.h b/libavfilter/bbox.h
> new file mode 100644
> index 0000000..dcf1994
> --- /dev/null
> +++ b/libavfilter/bbox.h
> @@ -0,0 +1,42 @@
> +/*
> + * Copyright (c) 2005 Robert Edele <yartrebo at 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;
> +} BoundingBox;
> +
> +/**
> + * Calculate the smallest rectangle that will encompass the
> + * region with values > min_val.
> + *
> + * The bounding rectangle is calculated by testing successive lines
> + * (from the four sides of the rectangle) until no more can be removed
> + * without removing logo pixels.
> + */
> +void calculate_bounding_rectangle(BoundingBox *bbox,
> +                                  const uint8_t *data, int linesize,
> +                                  int w, int h, int min_val);
> +
> +#endif /* AVFILTER_BBOX_H */
> diff --git a/libavfilter/vf_bbox.c b/libavfilter/vf_bbox.c
> new file mode 100644
> index 0000000..0b0a265
> --- /dev/null
> +++ b/libavfilter/vf_bbox.c
> @@ -0,0 +1,122 @@
> +/*
> + * 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 int config_props_input(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    BBoxContext *bbox = ctx->priv;
> +    bbox->hsub = av_pix_fmt_descriptors[inlink->format].log2_chroma_w;
> +    bbox->vsub = av_pix_fmt_descriptors[inlink->format].log2_chroma_h;
> +    return 0;
> +}
> +
> +static void end_frame(AVFilterLink *inlink)
> +{
> +    AVFilterContext *ctx = inlink->dst;
> +    BBoxContext *bbox = ctx->priv;
> +    AVFilterBufferRef *picref = inlink->cur_buf;
> +    BoundingBox box;
> +    int plane;
> +
> +    for (plane = 0; picref->data[plane] && plane < 4; plane++) {
> +        int w, h, vsub = 0, hsub = 0;
> +        if (plane == 1 || plane == 2) {
> +            hsub = bbox->hsub;
> +            vsub = bbox->vsub;
> +        }
> +        calculate_bounding_rectangle(&box, picref->data[plane], picref->linesize[plane],
> +                                     inlink->w>>hsub, inlink->h>>vsub, 16);

Is it right for chrominance planes? AFAIK, for chrominance, "neutral" values
are around 128, not 0.

> +        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 plane:%d x1:%d x2:%d y1:%d y2:%d w:%d h:%d"
> +               " crop=%d:%d:%d:%d drawbox=%d:%d:%d:%d\n",
> +               bbox->frame,
> +               av_ts2str(picref->pts), av_ts2timestr(picref->pts, &inlink->time_base),
> +               plane, box.x1, box.x2, box.y1, box.y2, w, h,
> +               w, h, box.x1, box.x2,    /* crop params */
> +               box.x1, box.y1, w, h);   /* drawbox params */
> +    }
> +
> +    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,

Alignment is strange.

> +          .get_video_buffer = avfilter_null_get_video_buffer,
> +          .config_props     = config_props_input,
> +          .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 }
> +    },
> +};

Thanks.

Regards,

-- 
  Nicolas George
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