Re: [FFmpeg-devel] [PATCH 1/7] avutil: add an API to handle 3D Reference Displays Information

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Timo Rothenpieler:
> From: James Almer <jamrial@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@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

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