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 <jua...@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,
--
Nicolas George
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