[FFmpeg-devel,1/3] libavutil: AVEncodeInfo data structures

AVEncodeInfoFrame data structure to store as AVFrameSideData of type
AV_FRAME_DATA_ENCODE_INFO.
The structure stores quantization index for each plane, DC/AC deltas
for luma and chroma planes, and an array of AVEncodeInfoBlock type
denoting position, size, and delta quantizer for each block in the
frame.
Can be extended to support extraction of other block information.

Signed-off-by: Juan De León <juandl@google.com>
---
 libavutil/Makefile      |   2 +
 libavutil/encode_info.c |  71 ++++++++++++++++++++++++++
 libavutil/encode_info.h | 110 ++++++++++++++++++++++++++++++++++++++++
 libavutil/frame.c       |   1 +
 libavutil/frame.h       |   7 +++
 5 files changed, 191 insertions(+)
 create mode 100644 libavutil/encode_info.c
 create mode 100644 libavutil/encode_info.h

Juan De León (12019-08-21):
> AVEncodeInfoFrame data structure to store as AVFrameSideData of type
> AV_FRAME_DATA_ENCODE_INFO.
> The structure stores quantization index for each plane, DC/AC deltas
> for luma and chroma planes, and an array of AVEncodeInfoBlock type
> denoting position, size, and delta quantizer for each block in the
> frame.
> Can be extended to support extraction of other block information.
> 
> Signed-off-by: Juan De León <juandl@google.com>
> ---
>  libavutil/Makefile      |   2 +
>  libavutil/encode_info.c |  71 ++++++++++++++++++++++++++
>  libavutil/encode_info.h | 110 ++++++++++++++++++++++++++++++++++++++++
>  libavutil/frame.c       |   1 +
>  libavutil/frame.h       |   7 +++
>  5 files changed, 191 insertions(+)
>  create mode 100644 libavutil/encode_info.c
>  create mode 100644 libavutil/encode_info.h
> 
> diff --git a/libavutil/Makefile b/libavutil/Makefile
> index 57e6e3d7e8..37cfb099e9 100644
> --- a/libavutil/Makefile
> +++ b/libavutil/Makefile
> @@ -24,6 +24,7 @@ HEADERS = adler32.h                                                     \
>            dict.h                                                        \
>            display.h                                                     \
>            downmix_info.h                                                \
> +          encode_info.h                                                 \
>            encryption_info.h                                             \
>            error.h                                                       \
>            eval.h                                                        \
> @@ -111,6 +112,7 @@ OBJS = adler32.o                                                        \
>         dict.o                                                           \
>         display.o                                                        \
>         downmix_info.o                                                   \
> +       encode_info.o                                                    \
>         encryption_info.o                                                \
>         error.o                                                          \
>         eval.o                                                           \
> diff --git a/libavutil/encode_info.c b/libavutil/encode_info.c
> new file mode 100644
> index 0000000000..91e43fce63
> --- /dev/null
> +++ b/libavutil/encode_info.c
> @@ -0,0 +1,71 @@
> +/*
> + * 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 <limits.h>
> +
> +#include "libavutil/encode_info.h"
> +#include "libavutil/mem.h"
> +
> +static int init_encode_info_data(AVEncodeInfoFrame *info, unsigned nb_blocks) {
> +    info->nb_blocks = nb_blocks;
> +    info->block_size = sizeof(AVEncodeInfoBlock);
> +    info->blocks_offset = offsetof(AVEncodeInfoFrame, blocks);
> +
> +    for(int i = 0; i < AV_NUM_DATA_POINTERS; i++)
> +        info->plane_q[i] = -1;
> +
> +    return 0;
> +}
> +
> +AVEncodeInfoFrame *av_encode_info_alloc(unsigned nb_blocks)
> +{
> +    // Check for possible size_t overflow
> +    if (nb_blocks - 1 > (SIZE_MAX - sizeof(AVEncodeInfoFrame)) / sizeof(AVEncodeInfoBlock))
> +        return NULL;
> +    //AVEncodeInfoFrame already allocates size for one element of AVEncodeInfoBlock
> +    size_t size = sizeof(AVEncodeInfoFrame) - sizeof(AVEncodeInfoBlock) +
> +                  FFMAX(1, nb_blocks) * sizeof(AVEncodeInfoBlock);
> +
> +    AVEncodeInfoFrame *ptr = av_mallocz(size);
> +    if (!ptr)
> +        return NULL;
> +
> +    init_encode_info_data(ptr, nb_blocks);
> +
> +    return ptr;
> +}
> +
> +AVEncodeInfoFrame *av_encode_info_create_side_data(AVFrame *frame, unsigned nb_blocks)
> +{
> +    // Check for size_t overflow

> +    if (nb_blocks - 1 > (SIZE_MAX - sizeof(AVEncodeInfoFrame)) / sizeof(AVEncodeInfoBlock))
> +        return NULL;

nb_blocks - 1 overflows for 0. Move the -1 right of the = as +1.

> +    //AVEncodeInfoFrame already allocates size for one element of AVEncodeInfoBlock

> +    size_t size = sizeof(AVEncodeInfoFrame) - sizeof(AVEncodeInfoBlock) +
> +                  FFMAX(1, nb_blocks) * sizeof(AVEncodeInfoBlock);

This code would be better shared in an inline function or macro instead
of duplicated. With a macro, you can include the check.

> +
> +    AVFrameSideData *sd = av_frame_new_side_data(frame,
> +                                                 AV_FRAME_DATA_ENCODE_INFO,
> +                                                 size);
> +    if (!sd)
> +        return NULL;
> +
> +    memset(sd->data, 0, size);
> +    init_encode_info_data((AVEncodeInfoFrame*)sd->data, nb_blocks);
> +
> +    return (AVEncodeInfoFrame*)sd->data;
> +}
> diff --git a/libavutil/encode_info.h b/libavutil/encode_info.h
> new file mode 100644
> index 0000000000..8afe0c9c9e
> --- /dev/null
> +++ b/libavutil/encode_info.h
> @@ -0,0 +1,110 @@
> +/*
> + * 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_ENCODE_INFO_H
> +#define AVUTIL_ENCODE_INFO_H
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/frame.h"
> +
> +/**
> + * Data structure for extracting block data, stored as an array in AVEncodeInfoFrame.
> + */
> +typedef struct AVEncodeInfoBlock{
> +    /**
> +     * Distance in luma pixels from the top-left corner of the visible frame
> +     * to the top-left corner of the block.
> +     * Can be negative if top/right padding is present on the coded frame.
> +     */
> +    int src_x, src_y;
> +    /**
> +     * Width and height of the block in luma pixels.
> +     */
> +    int w, h;
> +    /**
> +     * Delta quantization index for the block with respect to the frame.
> +     */
> +    int delta_q;
> +} AVEncodeInfoBlock;
> +
> +/**
> + * Frame encoding info, used as AVFrameSideData. Data in this structure concerns
> + * the whole frame.
> + * Additional entries may be added without bumping major before nb_blocks,
> + * so using the accessor function av_encode_info_get_block() is recommended.
> + */
> +typedef struct AVEncodeInfoFrame {
> +    /**
> +     * Base plane quantizer for the frame, set to -1 when value is unsupported.
> +     */
> +    int plane_q[AV_NUM_DATA_POINTERS];
> +    /**
> +     * DC/AC quantizer index delta, set to -1 when value is value unsupported.
> +     */
> +    int ac_q, dc_q;
> +    /**
> +     * DC/AC chroma quantizer index delta, set to -1 when value is value unsupported.
> +     */
> +    int ac_chroma_q, dc_chroma_q;
> +    /**
> +     * Number of blocks in the array, may be 0.
> +     */
> +    unsigned nb_blocks;
> +    /**
> +     * Offset in this structure at which blocks begin in bytes. May not match
> +     * offsetof(AVEncodeInfoFrame, blocks).
> +     */
> +    size_t blocks_offset;
> +    /*
> +     * Size of each block in bytes. May not match sizeof(AVEncodeInfoBlock).
> +     */
> +    size_t block_size;
> +
> +    /*
> +     * Array of blocks, with a total size of block_size*nb_blocks, the [1]
> +     * is meant for compatibility with C++.
> +     */
> +    AVEncodeInfoBlock blocks[1];
> +} AVEncodeInfoFrame;
> +
> +/*
> + * Gets the block at the specified {@code idx}. Must be between 0 and nb_blocks.
> + */
> +static inline AVEncodeInfoBlock *av_encode_info_get_block(AVEncodeInfoFrame *info, unsigned idx)
> +{
> +    av_assert0(idx < info->nb_blocks);
> +
> +    return (AVEncodeInfoBlock *)((uint8_t *)info + info->blocks_offset + idx*info->block_size);
> +}
> +
> +/**
> + * Allocates memory for AVEncodeInfoFrame plus an array of
> + * {@code nb_blocks} AVEncodeInfoBlock and initializes the variables.
> + * Can be freed with a normal av_free() call.
> + */
> +AVEncodeInfoFrame *av_encode_info_alloc(unsigned nb_blocks);
> +
> +/**
> + * Allocates memory for AVEncodeInfoFrame plus an array of
> + * {@code nb_blocks} AVEncodeInfoBlock in the given AVFrame {@code frame}
> + * as AVFrameSideData of type AV_FRAME_DATA_ENCODE_INFO
> + * and initializes the variables.
> + */
> +AVEncodeInfoFrame *av_encode_info_create_side_data(AVFrame *frame, unsigned nb_blocks);
> +
> +#endif /* AVUTIL_ENCODE_INFO_H */
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index dcf1fc3d17..65c25e6cd7 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -842,6 +842,7 @@ const char *av_frame_side_data_name(enum AVFrameSideDataType type)
>  #endif
>      case AV_FRAME_DATA_DYNAMIC_HDR_PLUS: return "HDR Dynamic Metadata SMPTE2094-40 (HDR10+)";
>      case AV_FRAME_DATA_REGIONS_OF_INTEREST: return "Regions Of Interest";
> +    case AV_FRAME_DATA_ENCODE_INFO:                 return "AVEncodeInfo";
>      }
>      return NULL;
>  }
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 5d3231e7bb..ec112c5d15 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -179,6 +179,13 @@ enum AVFrameSideDataType {
>       * array element is implied by AVFrameSideData.size / AVRegionOfInterest.self_size.
>       */
>      AV_FRAME_DATA_REGIONS_OF_INTEREST,
> +    /**
> +     * Extract frame and block encode info from supported decoders. The data
> +     * stored is an AVEncodeInfoFrame type, which contains an array of
> +     * AVEncodeInfoBlock. Described in libavuitls/encode_info.h
> +     * Can be allocated in the frame directly with av_encode_info_create_side_data().
> +     */
> +    AV_FRAME_DATA_ENCODE_INFO,
>  };
>  
>  enum AVActiveFormatDescription {

Regards,

On Fri, Aug 23, 2019 at 8:07 AM Nicolas George <george@nsup.org> wrote:

> > +    if (nb_blocks - 1 > (SIZE_MAX - sizeof(AVEncodeInfoFrame)) /
> sizeof(AVEncodeInfoBlock))
> > +        return NULL;
>
> nb_blocks - 1 overflows for 0. Move the -1 right of the = as +1.
>
> > +    //AVEncodeInfoFrame already allocates size for one element of
> AVEncodeInfoBlock
>
> > +    size_t size = sizeof(AVEncodeInfoFrame) - sizeof(AVEncodeInfoBlock)
> +
> > +                  FFMAX(1, nb_blocks) * sizeof(AVEncodeInfoBlock);
>
> This code would be better shared in an inline function or macro instead
> of duplicated. With a macro, you can include the check.
>

I changed it to an inline function, returns SIZE_MAX if it fails to make
av_malloc() fail and return NULL.
Thanks for the feedback.

Juan De León (12019-08-23):
> I changed it to an inline function, returns SIZE_MAX if it fails to make
> av_malloc() fail and return NULL.

You neglected to check for SIZE_MAX afterwards. I suspect there are
architectures where such a malloc could succeed.

If you insist on a function rather than a macro, I personally consider
bad style to rely on a magic value for error: return a boolean for
success and pass the size through a pointer.

But in this case, a macro would probably be the simplest.

Regards,

On Fri, Aug 23, 2019 at 12:28 PM Nicolas George <george@nsup.org> wrote:

> Juan De León (12019-08-23):
> > I changed it to an inline function, returns SIZE_MAX if it fails to make
> > av_malloc() fail and return NULL.
>
> You neglected to check for SIZE_MAX afterwards. I suspect there are
> architectures where such a malloc could succeed.
>
I doubt it since av_malloc() checks for size > INT_MAX - 32.
Maybe in a 16 bit system.

But in this case, a macro would probably be the simplest.
>
I'm sending a new patch with a macro.