[FFmpeg-devel] [PATCH 1/3] lavu: add support for Content Light Level side metadata

[Hendrik Leppkes]

On Thu, Mar 30, 2017 at 4:31 PM, Steve Lhomme <robux4 at gmail.com> wrote:
> As found in HEVC.
>
> I put the code in mastering_display_metadata as they usually go together in
> Blu-Ray UHD sources.
> ---
>  libavutil/frame.c                      |  1 +
>  libavutil/frame.h                      |  6 ++++++
>  libavutil/mastering_display_metadata.c | 18 ++++++++++++++++
>  libavutil/mastering_display_metadata.h | 39 ++++++++++++++++++++++++++++++++++
>  libavutil/version.h                    |  2 +-
>  5 files changed, 65 insertions(+), 1 deletion(-)
>
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index 8811dcdcfe..dd12c5549c 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -772,6 +772,7 @@ const char *av_frame_side_data_name(enum AVFrameSideDataType type)
>      case AV_FRAME_DATA_SKIP_SAMPLES:    return "Skip samples";
>      case AV_FRAME_DATA_AUDIO_SERVICE_TYPE:          return "Audio service type";
>      case AV_FRAME_DATA_MASTERING_DISPLAY_METADATA:  return "Mastering display metadata";
> +    case AV_FRAME_DATA_CONTENT_LIGHT_LEVEL:         return "Content light level metadata";
>      case AV_FRAME_DATA_GOP_TIMECODE:                return "GOP timecode";
>      }
>      return NULL;
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 7cb78a1a44..45e21a11d4 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -127,6 +127,12 @@ enum AVFrameSideDataType {
>       * libavutil/spherical.h.
>       */
>      AV_FRAME_DATA_SPHERICAL,
> +
> +    /**
> +     * Content light level (based on CEA 861.3). This payload containts data in
> +     * the form of the AVContentLightMetadata struct.
> +     */
> +    AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
>  };
>
>  enum AVActiveFormatDescription {
> diff --git a/libavutil/mastering_display_metadata.c b/libavutil/mastering_display_metadata.c
> index e1683e55c7..c41c90db12 100644
> --- a/libavutil/mastering_display_metadata.c
> +++ b/libavutil/mastering_display_metadata.c
> @@ -41,3 +41,21 @@ AVMasteringDisplayMetadata *av_mastering_display_metadata_create_side_data(AVFra
>
>      return (AVMasteringDisplayMetadata *)side_data->data;
>  }
> +
> +AVContentLightMetadata *av_content_light_metadata_alloc(void)
> +{
> +    return av_mallocz(sizeof(AVContentLightMetadata));
> +}
> +
> +AVContentLightMetadata *av_content_light_metadata_create_side_data(AVFrame *frame)
> +{
> +    AVFrameSideData *side_data = av_frame_new_side_data(frame,
> +                                                        AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
> +                                                        sizeof(AVContentLightMetadata));
> +    if (!side_data)
> +        return NULL;
> +
> +    memset(side_data->data, 0, sizeof(AVContentLightMetadata));
> +
> +    return (AVContentLightMetadata *)side_data->data;
> +}
> diff --git a/libavutil/mastering_display_metadata.h b/libavutil/mastering_display_metadata.h
> index 936533fec4..5ad7f5bd42 100644
> --- a/libavutil/mastering_display_metadata.h
> +++ b/libavutil/mastering_display_metadata.h
> @@ -86,4 +86,43 @@ AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc(void);
>   */
>  AVMasteringDisplayMetadata *av_mastering_display_metadata_create_side_data(AVFrame *frame);
>
> +/**
> + * Content light level needed by to transmit HDR over HDMI (CEA 861.3).
> + *
> + * To be used as payload of a AVFrameSideData or AVPacketSideData with the
> + * appropriate type.
> + *
> + * @note The struct should be allocated with av_content_light_metadata_alloc()
> + *       and its size is not a part of the public ABI.
> + */
> +typedef struct AVContentLightMetadata {
> +    /**
> +     * Max content light level (cd/m^2).
> +     */
> +    AVRational max_content_light_level;
> +
> +    /**
> +     * Max avereage light level per picture (cd/m^2).

It might be better to call this how the spec calls it: Maximum
frame-average light level (MaxFALL), instead of coming up with a
slight rewording, that could just cause confusion.
Maybe including the common acronyms MaxCLL and MaxFALL for both
elements might be sensible too.

> +     */
> +    AVRational max_pic_avg_light_level;
> +} AVContentLightMetadata;
> +
> +/**
> + * Allocate an AVContentLightMetadata structure and set its fields to
> + * default values. The resulting struct can be freed using av_freep().
> + *
> + * @return An AVContentLightMetadata filled with default values or NULL
> + *         on failure.
> + */
> +AVContentLightMetadata *av_content_light_metadata_alloc(void);
> +
> +/**
> + * Allocate a complete AVContentLightMetadata and add it to the frame.
> + *
> + * @param frame The frame which side data is added to.
> + *
> + * @return The AVContentLightMetadata structure to be filled by caller.
> + */
> +AVContentLightMetadata *av_content_light_metadata_create_side_data(AVFrame *frame);
> +
>  #endif /* AVUTIL_MASTERING_DISPLAY_METADATA_H */
> diff --git a/libavutil/version.h b/libavutil/version.h
> index a14c0e7eb2..fedc6fa177 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>   */
>
>  #define LIBAVUTIL_VERSION_MAJOR  55
> -#define LIBAVUTIL_VERSION_MINOR  53
> +#define LIBAVUTIL_VERSION_MINOR  54
>  #define LIBAVUTIL_VERSION_MICRO 100
>
>  #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
> --
> 2.11.1
>
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