Re: [FFmpeg-devel] [PATCH v8 1/6] lavu/frame: Add Dolby Vision metadata side data type

[Lynne <dev@lynne.ee>]

20 Dec 2021, 16:31 by ffmpeg@haasn.xyz:

> From: Niklas Haas <git@haasn.dev>
>
> Signed-off-by: Niklas Haas <git@haasn.dev>
> ---
>  doc/APIchanges        |   3 +
>  libavutil/dovi_meta.c |  12 ++++
>  libavutil/dovi_meta.h | 143 ++++++++++++++++++++++++++++++++++++++++++
>  libavutil/frame.c     |   1 +
>  libavutil/frame.h     |   9 ++-
>  libavutil/version.h   |   2 +-
>  6 files changed, 168 insertions(+), 2 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 17aa664ca3..ff78edec88 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -14,6 +14,9 @@ libavutil:     2021-04-27
>  
>  API changes, most recent first:
>  
> +2021-12-xx - xxxxxxxxxx - lavu 57.12.100 - frame.h
> +  Add AV_FRAME_DATA_DOVI_METADATA.
> +
>  2021-12-xx - xxxxxxxxxx - lavf 59.10.100 - avformat.h
>  Add AVFormatContext io_close2 which returns an int
>  
> diff --git a/libavutil/dovi_meta.c b/libavutil/dovi_meta.c
> index 7bd08f6c54..60b4cb2376 100644
> --- a/libavutil/dovi_meta.c
> +++ b/libavutil/dovi_meta.c
> @@ -33,3 +33,15 @@ AVDOVIDecoderConfigurationRecord *av_dovi_alloc(size_t *size)
>  
>  return dovi;
>  }
> +
> +AVDOVIMetadata *av_dovi_metadata_alloc(size_t *size)
> +{
> +    AVDOVIMetadata *dovi = av_mallocz(sizeof(AVDOVIMetadata));
> +    if (!dovi)
> +        return NULL;
> +
> +    if (size)
> +        *size = sizeof(*dovi);
> +
> +    return dovi;
> +}
> diff --git a/libavutil/dovi_meta.h b/libavutil/dovi_meta.h
> index 299911d434..25e6d7b42f 100644
> --- a/libavutil/dovi_meta.h
> +++ b/libavutil/dovi_meta.h
> @@ -29,6 +29,7 @@
>  
>  #include <stdint.h>
>  #include <stddef.h>
> +#include "rational.h"
>  
>  /*
>  * DOVI configuration
> @@ -67,4 +68,146 @@ typedef struct AVDOVIDecoderConfigurationRecord {
>  */
>  AVDOVIDecoderConfigurationRecord *av_dovi_alloc(size_t *size);
>  
> +/**
> + * Dolby Vision RPU data header.
> + *
> + * @note Cannot be extended without an ABI bump.
> + */
> +typedef struct AVDOVIRpuDataHeader {
> +    uint8_t rpu_type;
> +    uint16_t rpu_format;
> +    uint8_t vdr_rpu_profile;
> +    uint8_t vdr_rpu_level;
> +    uint8_t chroma_resampling_explicit_filter_flag;
> +    uint8_t coef_data_type; /* informative, lavc always converts to fixed */
> +    uint8_t coef_log2_denom;
> +    uint8_t vdr_rpu_normalized_idc;
> +    uint8_t bl_video_full_range_flag;
> +    uint8_t bl_bit_depth; /* [8, 16] */
> +    uint8_t el_bit_depth; /* [8, 16] */
> +    uint8_t vdr_bit_depth; /* [8, 16] */
> +    uint8_t spatial_resampling_filter_flag;
> +    uint8_t el_spatial_resampling_filter_flag;
> +    uint8_t disable_residual_flag;
> +} AVDOVIRpuDataHeader;
> +
> +enum AVDOVIMappingMethod {
> +    AV_DOVI_MAPPING_POLYNOMIAL = 0,
> +    AV_DOVI_MAPPING_MMR = 1,
> +};
> +
> +/**
> + * Coefficients of a piece-wise function. The pieces of the function span the
> + * value ranges between two adjacent pivot values.
> + *
> + * @note Cannot be extended without an ABI bump.
> + */
> +#define AV_DOVI_MAX_PIECES 8
> +typedef struct AVDOVIReshapingCurve {
> +    uint8_t num_pivots;                         /* [2, 9] */
> +    uint16_t pivots[AV_DOVI_MAX_PIECES + 1];    /* sorted ascending */
> +    enum AVDOVIMappingMethod mapping_idc[AV_DOVI_MAX_PIECES];
> +    /* AV_DOVI_MAPPING_POLYNOMIAL */
> +    uint8_t poly_order[AV_DOVI_MAX_PIECES];     /* [1, 2] */
> +    int64_t poly_coef[AV_DOVI_MAX_PIECES][3];   /* x^0, x^1, x^2 */
> +    /* AV_DOVI_MAPPING_MMR */
> +    uint8_t mmr_order[AV_DOVI_MAX_PIECES];      /* [1, 3] */
> +    int64_t mmr_constant[AV_DOVI_MAX_PIECES];
> +    int64_t mmr_coef[AV_DOVI_MAX_PIECES][3/* order - 1 */][7];
> +} AVDOVIReshapingCurve;
> +
> +enum AVDOVINLQMethod {
> +    AV_DOVI_NLQ_NONE = -1,
> +    AV_DOVI_NLQ_LINEAR_DZ = 0,
> +};
> +
> +/**
> + * Coefficients of the non-linear inverse quantization. For the interpretation
> + * of these, see ETSI GS CCM 001.
> + *
> + * @note Cannot be extended without an ABI bump.
> + */
> +typedef struct AVDOVINLQParams {
> +    uint64_t nlq_offset;
> +    uint64_t vdr_in_max;
> +    /* AV_DOVI_NLQ_LINEAR_DZ */
> +    uint64_t linear_deadzone_slope;
> +    uint64_t linear_deadzone_threshold;
> +} AVDOVINLQParams;
> +
> +/**
> + * Dolby Vision RPU data mapping parameters.
> + *
> + * @note Cannot be extended without an ABI bump.
> + */
> +typedef struct AVDOVIDataMapping {
> +    uint8_t vdr_rpu_id;
> +    uint8_t mapping_color_space;
> +    uint8_t mapping_chroma_format_idc;
> +    AVDOVIReshapingCurve curves[3]; /* per component */
> +
> +    /* Non-linear inverse quantization */
> +    enum AVDOVINLQMethod nlq_method_idc;
> +    uint32_t num_x_partitions;
> +    uint32_t num_y_partitions;
> +    AVDOVINLQParams nlq[3]; /* per component */
> +} AVDOVIDataMapping;
> +
> +typedef struct AVDOVIColorMetadata {
> +    uint8_t dm_metadata_id;
> +    uint8_t scene_refresh_flag;
> +
> +    /**
> +     * Coefficients of the custom Dolby Vision IPT-PQ matrices. These are to be
> +     * used instead of the matrices indicated by the frame's colorspace tags.
> +     * The output of rgb_to_lms_matrix is to be fed into a BT.2020 LMS->RGB
> +     * matrix based on a Hunt-Pointer-Estevez transform, but without any
> +     * crosstalk. (See the definition of the ICtCp colorspace for more
> +     * information.)
> +     */
> +    AVRational ycc_to_rgb_matrix[9]; /* before PQ linearization */
> +    AVRational ycc_to_rgb_offset[3]; /* input offset of neutral value */
> +    AVRational rgb_to_lms_matrix[9]; /* after PQ linearization */
> +
> +    /**
> +     * Extra signal metadata (see Dolby patents for more info).
> +     */
> +    uint16_t signal_eotf;
> +    uint16_t signal_eotf_param0;
> +    uint16_t signal_eotf_param1;
> +    uint32_t signal_eotf_param2;
> +    uint8_t signal_bit_depth;
> +    uint8_t signal_color_space;
> +    uint8_t signal_chroma_format;
> +    uint8_t signal_full_range_flag; /* [0, 3] */
> +    uint16_t source_min_pq;
> +    uint16_t source_max_pq;
> +    uint16_t source_diagonal;
> +} AVDOVIColorMetadata;
> +
> +/**
> + * Combined struct representing a combination of header, mapping and color
> + * metadata, for attaching to frames as side data.
> + *
> + * @note The struct must be allocated with av_dovi_metadata_alloc() and
> + *       its size is not a part of the public ABI.
> + */
> +
> +typedef struct AVDOVIMetadata {
> +    AVDOVIRpuDataHeader header;
> +    AVDOVIDataMapping mapping;
> +    AVDOVIColorMetadata color;
>

I think we should version this by adding an integer version
field, and a compile-time header #define.
just in case more extra signalling is added. Then
we could support it in a sort of backwards-compatible way
by just documenting what has changed, and users could
make their own decisions about whether to present it 
as-is or error out.

Apart from that, patchset looks good to me.
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