[FFmpeg-devel] [PATCH V7 4/6] lavu: add side data AV_FRAME_DATA_BOUNDING_BOXES
Guo, Yejun
yejun.guo at intel.com
Thu Apr 8 05:48:21 EEST 2021
> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Lynne
> Sent: 2021年4月8日 5:04
> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH V7 4/6] lavu: add side data
> AV_FRAME_DATA_BOUNDING_BOXES
>
> Apr 7, 2021, 16:17 by yejun.guo at intel.com:
>
> > Signed-off-by: Guo, Yejun <yejun.guo at intel.com>
> > ---
> > doc/APIchanges | 2 +
> > libavutil/Makefile | 2 +
> > libavutil/boundingbox.c | 73 +++++++++++++++++++++++++
> > libavutil/boundingbox.h | 114
> ++++++++++++++++++++++++++++++++++++++++
> > libavutil/frame.c | 1 +
> > libavutil/frame.h | 7 +++
> > 6 files changed, 199 insertions(+)
> > create mode 100644 libavutil/boundingbox.c
> > create mode 100644 libavutil/boundingbox.h
> >
> > diff --git a/doc/APIchanges b/doc/APIchanges
> > index 9dfcc97d5c..81d01aac1e 100644
> > --- a/doc/APIchanges
> > +++ b/doc/APIchanges
> > @@ -14,6 +14,8 @@ libavutil: 2017-10-21
> >
> >
> > API changes, most recent first:
> > +2021-04-xx - xxxxxxxxxx - lavu 56.xx.100 - frame.h boundingbox.h
> > + Add AV_FRAME_DATA_BOUNDING_BOXES
> >
> > 2021-04-06 - xxxxxxxxxx - lavf 58.78.100 - avformat.h
> > Add avformat_index_get_entries_count(), avformat_index_get_entry(),
> > diff --git a/libavutil/Makefile b/libavutil/Makefile
> > index 27bafe9e12..f6d21bb5ce 100644
> > --- a/libavutil/Makefile
> > +++ b/libavutil/Makefile
> > @@ -11,6 +11,7 @@ HEADERS = adler32.h
> \
> > avutil.h \
> > base64.h \
> > blowfish.h \
> > + boundingbox.h
> \
> > bprint.h \
> > bswap.h \
> > buffer.h \
> > @@ -104,6 +105,7 @@ OBJS = adler32.o
> \
> > avsscanf.o
> \
> > base64.o
> \
> > blowfish.o
> \
> > + boundingbox.o
> \
> > bprint.o
> \
> > buffer.o \
> > cast5.o
> \
> > diff --git a/libavutil/boundingbox.c b/libavutil/boundingbox.c
> > new file mode 100644
> > index 0000000000..881661ec18
> > --- /dev/null
> > +++ b/libavutil/boundingbox.c
> > @@ -0,0 +1,73 @@
> > +/*
> > + * 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 "boundingbox.h"
> > +
> > +AVBoundingBoxHeader *av_bbox_alloc(uint32_t nb_bboxes, size_t
> *out_size)
> > +{
> > + size_t size;
> > + struct {
> > + AVBoundingBoxHeader header;
> > + AVBoundingBox boxes[];
> > + } *ret;
> > +
> > + size = sizeof(*ret);
> > + if (nb_bboxes > (SIZE_MAX - size) / sizeof(*ret->boxes))
> > + return NULL;
> > + size += sizeof(*ret->boxes) * nb_bboxes;
> > +
> > + ret = av_mallocz(size);
> > + if (!ret)
> > + return NULL;
> > +
> > + ret->header.nb_bboxes = nb_bboxes;
> > + ret->header.bbox_size = sizeof(*ret->boxes);
> > + ret->header.bboxes_offset = (char *)&ret->boxes - (char *)&ret->header;
> > +
> > + if (out_size)
> > + *out_size = sizeof(*ret);
> > +
> > + return &ret->header;
> > +}
> > +
> > +AVBoundingBoxHeader* av_bbox_create_side_data(AVFrame *frame,
> uint32_t nb_bboxes)
> >
>
> Fix this everywhere. We never put the * before the name. This is a misleading
> coding style that makes absolutely no sense.
Do you mean change from:
AVBoundingBoxHeader* av_bbox_create_side_data
to:
AVBoundingBoxHeader *av_bbox_create_side_data
Will fix it, thanks.
btw, I think the coding style is to put '*' just before the name, for example,
AVFrame *frame;
const AVClass *class;
>
>
> > +{
> > + AVBufferRef *buf;
> > + AVBoundingBoxHeader *header;
> > + size_t size;
> > +
> > + header = av_bbox_alloc(nb_bboxes, &size);
> > + if (!header)
> > + return NULL;
> > + if (size > INT_MAX) {
> > + av_freep(&header);
> > + return NULL;
> > + }
> > + buf = av_buffer_create((uint8_t *)header, size, NULL, NULL, 0);
> > + if (!buf) {
> > + av_freep(&header);
> > + return NULL;
> > + }
> > +
> > + if (!av_frame_new_side_data_from_buf(frame,
> AV_FRAME_DATA_BOUNDING_BOXES, buf)) {
> > + av_buffer_unref(&buf);
> > + return NULL;
> > + }
> > +
> > + return header;
> > +}
> > diff --git a/libavutil/boundingbox.h b/libavutil/boundingbox.h
> > new file mode 100644
> > index 0000000000..2b77c6c0dc
> > --- /dev/null
> > +++ b/libavutil/boundingbox.h
> > @@ -0,0 +1,114 @@
> > +/*
> > + * 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 AVUTIL_BOUNDINGBOX_H
> > +#define AVUTIL_BOUNDINGBOX_H
> > +
> > +#include "rational.h"
> > +#include "avassert.h"
> > +#include "frame.h"
> > +
> > +typedef struct AVBoundingBox {
> > + /**
> > + * Distance in pixels from the top edge of the frame to top
> > + * and bottom, and from the left edge of the frame to left and
> > + * right, defining the bounding box.
> > + */
> > + int top;
> > + int left;
> > + int bottom;
> > + int right;
> >
>
> Why not x, y, w, h?
> It makes more sense, all of coordinates go like this.
We want to keep it consistent with 'struct AVRegionOfInterest',
we also have a plan to add a filter which converts from bounding box
to RegionOfInterest which impacts the encoder.
>
>
> > +
> > +#define AV_BBOX_LABEL_NAME_MAX_SIZE 32
> >
>
> Better bump this to 64. It won't be enough, and will
> require a major bump to increment.
I usually don't see a very long label name, and you are right,
we'd better bump it for safe. Will change, thanks.
>
>
> > +
> > + /**
> > + * Detect result with confidence
> > + */
> > + char detect_label[AV_BBOX_LABEL_NAME_MAX_SIZE];
> > + AVRational detect_confidence;
> > +
> > + /**
> > + * At most 4 classifications based on the detected bounding box.
> > + * For example, we can get max 4 different attributes with 4 different
> > + * DNN models on one bounding box.
> > + * classify_count is zero if no classification.
> > + */
> > +#define AV_NUM_BBOX_CLASSIFY 4
> > + uint32_t classify_count;
> > + char
> classify_labels[AV_NUM_BBOX_CLASSIFY][AV_BBOX_LABEL_NAME_MAX_SIZE];
> > + AVRational classify_confidences[AV_NUM_BBOX_CLASSIFY];
> > +} AVBoundingBox;
> > +
> > +typedef struct AVBoundingBoxHeader {
> > + /**
> > + * Information about how the bounding box is generated.
> > + * for example, the DNN model name.
> > + */
> > + char source[128];
> > +
> > + /**
> > + * The size of frame when it is detected.
> > + */
> > + int frame_width;
> > + int frame_height;
> >
>
> Why? This side data is attached to AVFrames only, where we
> already have width and height.
The detection result will be used by other filters, for example,
dnn_classify (see https://github.com/guoyejun/ffmpeg/tree/classify).
The filter dnn_detect detects all the objects (cat, dog, person ...) in a
frame, while dnn_classify classifies one detected object (for example, person)
for its attribute (for example, emotion, etc.)
The filter dnn_classify have to check if the frame size is changed after
it is detected, to handle the below filter chain:
dnn_detect -> scale -> dnn_classify
>
>
> > +
> > + /**
> > + * Number of bounding boxes in the array.
> > + */
> > + uint32_t nb_bboxes;
> > +
> > + /**
> > + * Offset in bytes from the beginning of this structure at which
> > + * the array of bounding boxes starts.
> > + */
> > + size_t bboxes_offset;
> > +
> > + /**
> > + * Size of each bounding box in bytes.
> > + */
> > + size_t bbox_size;
> > +} AVBoundingBoxHeader;
> > +
> > +/*
> > + * Get the bounding box at the specified {@code idx}. Must be between 0
> and nb_bboxes.
> > + */
> > +static av_always_inline AVBoundingBox*
> > +av_get_bounding_box(const AVBoundingBoxHeader *header, unsigned int
> idx)
> > +{
> > + av_assert0(idx < header->nb_bboxes);
> > + return (AVBoundingBox *)((uint8_t *)header + header->bboxes_offset +
> > + idx * header->bbox_size);
> > +}
> > +
> > +/**
> > + * Allocates memory for AVBoundingBoxHeader, plus an array of {@code
> nb_bboxes}
> > + * AVBoundingBox, and initializes the variables.
> > + * Can be freed with a normal av_free() call.
> > + *
> > + * @param out_size if non-NULL, the size in bytes of the resulting data array
> is
> > + * written here.
> > + */
> > +AVBoundingBoxHeader *av_bbox_alloc(uint32_t nb_bboxes, size_t
> *out_size);
> > +
> > +/**
> > + * Allocates memory for AVBoundingBoxHeader, plus an array of {@code
> nb_bboxes}
> > + * AVBoundingBox, in the given AVFrame {@code frame} as
> AVFrameSideData of type
> > + * AV_FRAME_DATA_BOUNDING_BOXES and initializes the variables.
> > + */
> > +AVBoundingBoxHeader* av_bbox_create_side_data(AVFrame *frame,
> uint32_t nb_bboxes);
> > +#endif
> > diff --git a/libavutil/frame.c b/libavutil/frame.c
> > index fefb2b69c0..d8e86263af 100644
> > --- a/libavutil/frame.c
> > +++ b/libavutil/frame.c
> > @@ -853,6 +853,7 @@ const char *av_frame_side_data_name(enum
> AVFrameSideDataType type)
> > case AV_FRAME_DATA_VIDEO_ENC_PARAMS: return "Video
> encoding parameters";
> > case AV_FRAME_DATA_SEI_UNREGISTERED: return "H.26[45]
> User Data Unregistered SEI message";
> > case AV_FRAME_DATA_FILM_GRAIN_PARAMS: return "Film
> grain parameters";
> > + case AV_FRAME_DATA_BOUNDING_BOXES: return
> "Bounding boxes";
> > }
> > return NULL;
> > }
> > diff --git a/libavutil/frame.h b/libavutil/frame.h
> > index a5ed91b20a..41e22de02a 100644
> > --- a/libavutil/frame.h
> > +++ b/libavutil/frame.h
> > @@ -198,6 +198,13 @@ enum AVFrameSideDataType {
> > * Must be present for every frame which should have film grain applied.
> > */
> > AV_FRAME_DATA_FILM_GRAIN_PARAMS,
> > +
> > + /**
> > + * Bounding boxes for object detection and classification, the data is a
> AVBoundingBoxHeader
> > + * followed with an array of AVBoudingBox, and
> AVBoundingBoxHeader.nb_bboxes is the number
> > + * of array element.
> > + */
> > + AV_FRAME_DATA_BOUNDING_BOXES,
> > };
> >
>
> Finally, why call it a Bounding Box? It's not descriptive at all.
> How about "Object Classification"? It makes much more sense, it's
> exactly what this is. So AVObjectClassification, AVObjectClassification,
> AV_FRAME_DATA_OBJECT_CLASSIFICATION and so on.
In object detection papers, bounding box is usually used.
We'd better use the same term, imho, thanks.
More information about the ffmpeg-devel
mailing list