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

[Niklas Haas]

On Thu, 19 Dec 2024 05:36:08 -0500 Leo Izen <leo.izen at gmail.com> wrote:
>
>
> 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] };

Fixed locally. I won't bother sending a new version just for this fix.

>
>
> > +        }
> > +    }
> > +
> > +    /* 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;
> >   }
> >
>
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