[FFmpeg-devel] [PATCH V7 4/6] lavu: add side data AV_FRAME_DATA_BOUNDING_BOXES

Lynne dev at lynne.ee
Thu Apr 8 00:04:23 EEST 2021


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.


> +{
> +    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.


> +
> +#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.


> +
> +    /**
> +     * 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.


> +
> +    /**
> +     * 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.


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