[FFmpeg-devel] [PATCH] Add HDR dynamic metadata struct (for SPMTE 2094-40) to libavutil.

[Vittorio Giovara]

On Mon, Dec 17, 2018 at 5:53 PM Jan Ekström <jeebjp at gmail.com> wrote:

> On Tue, Dec 18, 2018 at 12:41 AM Vittorio Giovara
> <vittorio.giovara at gmail.com> wrote:
> >
> > On Mon, Dec 10, 2018 at 2:50 PM Mohammad Izadi <moh.izadi at gmail.com>
> wrote:
> >
> > > From: Mohammad Izadi <izadi at google.com>
> > >
> > > The dynamic metadata contains data for color volume transform -
> > > application 4 of SPMTE 2094-40:2016 standard. The data comes from HEVC
> in
> > > the SEI_TYPE_USER_DATA_REGISTERED_ITU_T_T35.
> > >
> > > I'll add support to HEVC in a follow-up.
> > >
> > > diff --git a/libavutil/frame.c b/libavutil/frame.c
> > > index 9b3fb13e68..c5f30b6847 100644
> > > --- a/libavutil/frame.c
> > > +++ b/libavutil/frame.c
> > > @@ -840,6 +840,7 @@ const char *av_frame_side_data_name(enum
> > > AVFrameSideDataType type)
> > >      case AV_FRAME_DATA_QP_TABLE_PROPERTIES:         return "QP table
> > > properties";
> > >      case AV_FRAME_DATA_QP_TABLE_DATA:               return "QP table
> > > data";
> > >  #endif
> > > +    case AV_FRAME_DATA_HDR_DYNAMIC_METADATA_SMPTE2094_40: return "HDR
> > > Dynamic Metadata SMPTE2094-40";
> > >
> >
> > I like
> VeryLongJavaLikeNamingForFunctionsAndDataTypesAsWellAsEnumsOfCourse
> > as much as the next guy, but this is overly too long and the related
> > structure name (AVDynamicMetadataSMPTE2094_40) is inconsistent with the
> > public type naming present in this project.
> >
> > If I may suggest, please use the following names:
> > - AV_FRAME_DATA_DYNAMIC_HDR for frame data type: it is obviously
> metadata,
> > and the fact that is based on SMPTE2094-40 should not be hardcoded in the
> > name
> > - dynamic_hdr.h as header name: again the fact that it's metadata does
> not
> > be carried everywhere
> > - AVDynamicHDR as structure name: short and to the point, and without
> spec
> > numbers or underscores
> >
>
> I don't think SMPTE ST.2094-XX utilized the same fields?
>
> I think SMPTE ST.2094-40 is Samsung's dynamic metadata which is effect
> usually called "HDR10+" ? Not just calling it AVDynamicHDR could come
> up useful if we plan on adding support for SMPTE ST.2094-10 which is
> one part of what's called "Dolby Vision" (even though it is just
> dynamic metadata - because of course you have to stick everything
> under a single marketing name).
>

It's still technically dynamic metadata but I get your point.
It could maybe be stored in dynamic_hdr.h header, and call it
AVDynamicHDRPlus to differenciate it from the future AVDolbyVisionHDR. What
do you think?


> Just my 20 cents.
>
> Jan
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-- 
Vittorio