[FFmpeg-devel] [PATCH 1/7] avutil: add an API to handle 3D Reference Displays Information
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Sun Jun 8 17:29:17 EEST 2025
Timo Rothenpieler:
> From: James Almer <jamrial at gmail.com>
>
> As defined in section G.14.3.2.3 of ITU-T H.265, it's required for proper
> signaling of MV-HEVC.
>
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> libavutil/Makefile | 2 +
> libavutil/tdrdi.c | 51 ++++++++++++++
> libavutil/tdrdi.h | 164 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 217 insertions(+)
> create mode 100644 libavutil/tdrdi.c
> create mode 100644 libavutil/tdrdi.h
>
> diff --git a/libavutil/Makefile b/libavutil/Makefile
> index 9ef118016b..94a56bb72f 100644
> --- a/libavutil/Makefile
> +++ b/libavutil/Makefile
> @@ -85,6 +85,7 @@ HEADERS = adler32.h \
> sha512.h \
> spherical.h \
> stereo3d.h \
> + tdrdi.h \
> threadmessage.h \
> time.h \
> timecode.h \
> @@ -179,6 +180,7 @@ OBJS = adler32.o \
> slicethread.o \
> spherical.o \
> stereo3d.o \
> + tdrdi.o \
> threadmessage.o \
> time.o \
> timecode.o \
> diff --git a/libavutil/tdrdi.c b/libavutil/tdrdi.c
> new file mode 100644
> index 0000000000..26192a1d2f
> --- /dev/null
> +++ b/libavutil/tdrdi.c
> @@ -0,0 +1,51 @@
> +/*
> + * 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 <stddef.h>
> +#include <stdint.h>
> +
> +#include "mem.h"
> +#include "tdrdi.h"
> +
> +AV3DReferenceDisplaysInfo *av_tdrdi_alloc(unsigned int nb_displays, size_t *out_size)
> +{
> + struct TestStruct {
> + AV3DReferenceDisplaysInfo p;
> + AV3DReferenceDisplay b;
> + };
> + const size_t entries_offset = offsetof(struct TestStruct, b);
> + size_t size = entries_offset;
> + AV3DReferenceDisplaysInfo *tdrdi;
> +
> + if (nb_displays > (SIZE_MAX - size) / sizeof(AV3DReferenceDisplay))
> + return NULL;
> + size += sizeof(AV3DReferenceDisplay) * nb_displays;
> +
> + tdrdi = av_mallocz(size);
> + if (!tdrdi)
> + return NULL;
> +
> + tdrdi->num_ref_displays = nb_displays;
> + tdrdi->entry_size = sizeof(AV3DReferenceDisplay);
> + tdrdi->entries_offset = entries_offset;
> +
> + if (out_size)
> + *out_size = size;
> +
> + return tdrdi;
> +}
> diff --git a/libavutil/tdrdi.h b/libavutil/tdrdi.h
> new file mode 100644
> index 0000000000..8dcca42c7b
> --- /dev/null
> +++ b/libavutil/tdrdi.h
> @@ -0,0 +1,164 @@
> +/*
> + * 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
> + * @ingroup lavu_video_3d_reference_displays_info
> + * Spherical video
> + */
> +
> +#ifndef AVUTIL_TDRDI_H
> +#define AVUTIL_TDRDI_H
> +
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +#include "libavutil/avassert.h"
> +
> +/**
> + * @defgroup lavu_video_3d_reference_displays_info 3D Reference Displays Information
> + * @ingroup lavu_video
> + *
> + * The 3D Reference Displays Information describes information about the reference display
> + * width(s) and reference viewing distance(s) as well as information about the corresponding
> + * reference stereo pair(s).
> + * @{
> + */
> +
> +#define AV_TDRDI_MAX_NUM_REF_DISPLAY 32
> +
> +/**
> + * This structure describes information about the reference display width(s) and reference
> + * viewing distance(s) as well as information about the corresponding reference stereo pair(s).
> + * See section G.14.3.2.3 of ITU-T H.265 for more information.
> + *
> + * @note The struct must be allocated with av_tdrdi_alloc() and
> + * its size is not a part of the public ABI.
> + */
> +typedef struct AV3DReferenceDisplaysInfo {
> + /**
> + * The exponent of the maximum allowable truncation error for
> + * {exponent,mantissa}_ref_display_width as given by 2<sup>(-prec_ref_display_width)</sup>.
> + */
> + uint8_t prec_ref_display_width;
> +
> + /**
> + * A flag to indicate the presence of reference viewing distance.
> + * If false, the values of prec_ref_viewing_dist, exponent_ref_viewing_distance,
> + * and mantissa_ref_viewing_distance are undefined.
> + */
> + uint8_t ref_viewing_distance_flag;
> +
> + /**
> + * The exponent of the maximum allowable truncation error for
> + * {exponent,mantissa}_ref_viewing_distance as given by 2<sup>^(-prec_ref_viewing_dist)</sup>.
> + * The value of prec_ref_viewing_dist shall be in the range of 0 to 31, inclusive.
> + */
> + uint8_t prec_ref_viewing_dist;
> +
> + /**
> + * The number of reference displays that are signalled in this struct.
> + * Allowed range is 1 to 32, inclusive.
> + */
> + uint8_t num_ref_displays;
> +
> + /**
> + * Offset in bytes from the beginning of this structure at which the array
> + * of reference displays starts.
> + */
> + size_t entries_offset;
> +
> + /**
> + * Size of each entry in bytes. May not match sizeof(AV3DReferenceDisplay).
> + */
> + size_t entry_size;
> +} AV3DReferenceDisplaysInfo;
> +
> +/**
> + * Data structure for single deference display information.
> + * It is allocated as a part of AV3DReferenceDisplaysInfo and should be retrieved with
> + * av_tdrdi_get_display().
> + *
> + * sizeof(AV3DReferenceDisplay) is not a part of the ABI and new fields may be
> + * added to it.
> +*/
> +typedef struct AV3DReferenceDisplay {
> + /**
> + * The ViewId of the left view of a stereo pair corresponding to the n-th reference display.
> + */
> + uint16_t left_view_id;
> +
> + /**
> + * The ViewId of the left view of a stereo pair corresponding to the n-th reference display.
> + */
> + uint16_t right_view_id;
> +
> + /**
> + * The exponent part of the reference display width of the n-th reference display.
> + */
> + uint8_t exponent_ref_display_width;
> +
> + /**
> + * The mantissa part of the reference display width of the n-th reference display.
> + */
> + uint8_t mantissa_ref_display_width;
> +
> + /**
> + * Tthe exponent part of the reference viewing distance of the n-th reference display.
> + */
> + uint8_t exponent_ref_viewing_distance;
> +
> + /**
> + * The mantissa part of the reference viewing distance of the n-th reference display.
> + */
> + uint8_t mantissa_ref_viewing_distance;
> +
> + /**
> + * An array of flags to indicates that the information about additional horizontal shift of
> + * the left and right views for the n-th reference display is present.
> + */
> + uint8_t additional_shift_present_flag;
> +
> + /**
> + * The recommended additional horizontal shift for a stereo pair corresponding to the n-th
> + * reference baseline and the n-th reference display.
> + */
> + int16_t num_sample_shift;
> +} AV3DReferenceDisplay;
> +
> +static av_always_inline AV3DReferenceDisplay*
> +av_tdrdi_get_display(AV3DReferenceDisplaysInfo *tdrdi, unsigned int idx)
> +{
> + av_assert0(idx < tdrdi->num_ref_displays);
> + return (AV3DReferenceDisplay *)((uint8_t *)tdrdi + tdrdi->entries_offset +
> + idx * tdrdi->entry_size);
> +}
> +
> +/**
> + * Allocate a AV3DReferenceDisplaysInfo structure and initialize its fields to default
> + * values.
> + *
> + * @return the newly allocated struct or NULL on failure
> + */
> +AV3DReferenceDisplaysInfo *av_tdrdi_alloc(unsigned int nb_displays, size_t *size);
> +
> +/**
> + * @}
> + */
> +
> +#endif /* AVUTIL_TDRDI_H */
I don't like that you add another allocator for this; instead we should
add a generic allocator for the frame side-data types.
- Andreas
More information about the ffmpeg-devel
mailing list