Re: [FFmpeg-devel] [PATCH 1/4] avutil: add ambient viewing environment metadata side data

[James Almer <jamrial@gmail.com>]

On 3/27/2022 8:25 PM, lance.lmwang@gmail.com wrote:
> From: Limin Wang <lance.lmwang@gmail.com>
> 
> Signed-off-by: Limin Wang <lance.lmwang@gmail.com>
> ---
>   libavutil/Makefile                       |  2 +
>   libavutil/ambient_viewing_env_metadata.c | 47 +++++++++++++++++++++
>   libavutil/ambient_viewing_env_metadata.h | 72 ++++++++++++++++++++++++++++++++
>   libavutil/frame.c                        |  1 +
>   libavutil/frame.h                        |  6 +++
>   5 files changed, 128 insertions(+)
>   create mode 100644 libavutil/ambient_viewing_env_metadata.c
>   create mode 100644 libavutil/ambient_viewing_env_metadata.h
> 
> diff --git a/libavutil/Makefile b/libavutil/Makefile
> index 81df3b0..e388d33 100644
> --- a/libavutil/Makefile
> +++ b/libavutil/Makefile
> @@ -26,6 +26,7 @@ HEADERS = adler32.h                                                     \
>             display.h                                                     \
>             dovi_meta.h                                                   \
>             downmix_info.h                                                \
> +          ambient_viewing_env_metadata.h                                \
>             encryption_info.h                                             \
>             error.h                                                       \
>             eval.h                                                        \
> @@ -119,6 +120,7 @@ OBJS = adler32.o                                                        \
>          display.o                                                        \
>          dovi_meta.o                                                      \
>          downmix_info.o                                                   \
> +       ambient_viewing_env_metadata.o                                   \
>          encryption_info.o                                                \
>          error.o                                                          \
>          eval.o                                                           \
> diff --git a/libavutil/ambient_viewing_env_metadata.c b/libavutil/ambient_viewing_env_metadata.c
> new file mode 100644
> index 0000000..7006b64
> --- /dev/null
> +++ b/libavutil/ambient_viewing_env_metadata.c
> @@ -0,0 +1,47 @@
> +/**
> + * Copyright (c) 2022 Limin Wang <lance.lmwang@gmail.com>
> + *
> + * 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 <stdint.h>
> +#include <string.h>
> +#include "ambient_viewing_env_metadata.h"
> +#include "mem.h"
> +
> +AVAmbientViewingEnvMetadata *av_ambient_viewing_env_metadata_alloc(size_t *size)
> +{
> +    AVAmbientViewingEnvMetadata *metadata = av_mallocz(sizeof(*metadata));
> +
> +    if (size)
> +        *size = sizeof(*metadata);
> +
> +    return metadata;
> +}
> +
> +AVAmbientViewingEnvMetadata *av_ambient_viewing_env_metadata_create_side_data(AVFrame *frame)
> +{
> +    AVFrameSideData *side_data = av_frame_new_side_data(frame,
> +            AV_FRAME_DATA_AMBIENT_VIEWING_ENV,
> +            sizeof(AVAmbientViewingEnvMetadata));
> +    if (!side_data)
> +        return NULL;
> +
> +    memset(side_data->data, 0, sizeof(AVAmbientViewingEnvMetadata));
> +
> +    return (AVAmbientViewingEnvMetadata *)side_data->data;
> +}
> diff --git a/libavutil/ambient_viewing_env_metadata.h b/libavutil/ambient_viewing_env_metadata.h
> new file mode 100644
> index 0000000..b0fbcd0
> --- /dev/null
> +++ b/libavutil/ambient_viewing_env_metadata.h
> @@ -0,0 +1,72 @@
> +/*
> + * Copyright (c) 2022 Limin Wang <lance.lmwang@gmail.com>
> + *
> + * 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_AMBIENT_VIEWING_ENV_METADATA_H
> +#define AVUTIL_AMBIENT_VIEWING_ENV_METADATA_H
> +
> +#include "frame.h"
> +
> +
> +/**
> + * The characteristics of the nominal ambient viewing environment for
> + * the display of the associated video content.
> + * To be used as payload of a AVFrameSideData the appropriate type.
> + *
> + * @note The struct should be allocated with av_ambient_viewing_env_metadata_alloc()
> + *       and its size is not a part of the public ABI.
> + */
> +typedef struct AVAmbientViewingEnvMetadata {
> +    /**
> +     * specifies the environmental illuminance of the ambient viewing
> +     * environment in units of 0.0001 lux.
> +     * ambient_illuminance shall not be equal to 0.
> +     */
> +    uint32_t ambient_illuminance;
> +    /**
> +     * specify the normalized x and y chromaticity coordinates, respectively,
> +     * of the environmental ambient light in the nominal viewing environment,
> +     * according to the CIE 1931 definition of x and y as specified in ISO
> +     * 11664-1 (see also ISO 11664-3 and CIE 15), in normalized increments of
> +     * 0.00002. The values of ambient_light_x and ambient_light_y shall be in
> +     * the range of 0 to 50 000
> +     */
> +    uint16_t ambient_light_x;
> +    uint16_t ambient_light_y;
> +} AVAmbientViewingEnvMetadata;

We don't need a new header for this. Just add it to 
mastering_display_metadata.h. The other structs there are based on other 
entries from the same spec (H.274) and have similar purposes.

> +
> +/**
> + * Allocate an AVAmbientViewingEnvMetadata structure and set its fields to
> + * default values. The resulting struct can be freed using av_freep().
> + *
> + * @return An AVAmbientViewingEnvMetadata filled with default values or NULL
> + *         on failure.
> + */
> +AVAmbientViewingEnvMetadata *av_ambient_viewing_env_metadata_alloc(size_t *size);
> +
> +/**
> + * Allocate a complete AVAmbientViewingEnvMetadata and add it to the frame.
> + *
> + * @param frame The frame which side data is added to.
> + *
> + * @return The AVAmbientViewingEnvMetadata structure to be filled by caller.
> + */
> +AVAmbientViewingEnvMetadata *av_ambient_viewing_env_metadata_create_side_data(AVFrame *frame);
> +
> +#endif /* AVUTIL_AMBIENT_VIEWING_ENV_METADATA_H */
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index fbb869f..8882da2 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -815,6 +815,7 @@ const char *av_frame_side_data_name(enum AVFrameSideDataType type)
>       case AV_FRAME_DATA_DETECTION_BBOXES:            return "Bounding boxes for object detection and classification";
>       case AV_FRAME_DATA_DOVI_RPU_BUFFER:             return "Dolby Vision RPU Data";
>       case AV_FRAME_DATA_DOVI_METADATA:               return "Dolby Vision Metadata";
> +    case AV_FRAME_DATA_AMBIENT_VIEWING_ENV:         return "Ambient Viewing Environment";
>       }
>       return NULL;
>   }
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 33fac20..f7b1d4e 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -209,6 +209,12 @@ enum AVFrameSideDataType {
>        * volume transform - CUVA 005.1-2021.
>        */
>       AV_FRAME_DATA_DYNAMIC_HDR_VIVID,
> +
> +    /**
> +     * ambient viewing environment for a video frame, as described by
> +     * the AVAmbientViewingEnvMetadata.
> +     */
> +    AV_FRAME_DATA_AMBIENT_VIEWING_ENV,
>   };
>   
>   enum AVActiveFormatDescription {
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