[FFmpeg-devel] [PATCH v2 04/17] swscale/utils: read HDR mastering metadata from AVFrame

[Leo Izen]

On 12/16/24 6:17 AM, Niklas Haas wrote:
> From: Niklas Haas <git at haasn.dev>
> 
> ---
>   libswscale/utils.c | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
> 
> diff --git a/libswscale/utils.c b/libswscale/utils.c
> index 2d8fc10beb..3d3fcadacc 100644
> --- a/libswscale/utils.c
> +++ b/libswscale/utils.c
> @@ -46,6 +46,7 @@
>   #include "libavutil/imgutils.h"
>   #include "libavutil/intreadwrite.h"
>   #include "libavutil/libm.h"
> +#include "libavutil/mastering_display_metadata.h"
>   #include "libavutil/mathematics.h"
>   #include "libavutil/mem.h"
>   #include "libavutil/opt.h"
> @@ -2655,6 +2656,7 @@ SwsFormat ff_fmt_from_frame(const AVFrame *frame, int field)
>   {
>       const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(frame->format);
>       const AVColorPrimariesDesc *primaries;
> +    AVFrameSideData *sd;
>   
>       SwsFormat fmt = {
>           .width  = frame->width,
> @@ -2727,6 +2729,26 @@ SwsFormat ff_fmt_from_frame(const AVFrame *frame, int field)
>       if (primaries)
>           fmt.color.gamut = primaries->prim;
>   
> +    if ((sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MASTERING_DISPLAY_METADATA))) {
> +        const AVMasteringDisplayMetadata *mdm = (const AVMasteringDisplayMetadata *) sd->data;
> +        if (mdm->has_luminance) {
> +            fmt.color.min_luma = mdm->min_luminance;
> +            fmt.color.max_luma = mdm->max_luminance;
> +        }
> +
> +        if (mdm->has_primaries) {
> +            /* Ignore mastering display white point as it has no bearance on
> +             * the underlying content */
> +            fmt.color.gamut.r = (AVCIExy) { mdm->display_primaries[0][0], mdm->display_primaries[0][1] };
> +            fmt.color.gamut.g = (AVCIExy) { mdm->display_primaries[1][0], mdm->display_primaries[1][1] };
> +            fmt.color.gamut.b = (AVCIExy) { mdm->display_primaries[2][0], mdm->display_primaries[2][1] };

I think this kind of initializer chokes MSVC. We need to use something like:

fmt.color.gamut.r = { .x = mdm->display_primaries[0][0], .y = 
mdm->display_primaries[0][1] };


> +        }
> +    }
> +
> +    /* PQ is always scaled down to absolute zero, so ignore mastering metadata */
> +    if (fmt.color.trc == AVCOL_TRC_SMPTE2084)
> +        fmt.color.min_luma = av_make_q(0, 1);
> +
>       return fmt;
>   }
>