[FFmpeg-devel] [PATCH 4/6 v2] avutil/mastering_display_metadata: add a new allocator function that returns a size

[Anton Khirnov]

Quoting James Almer (2024-03-27 13:35:35)
> On 3/27/2024 4:41 AM, Anton Khirnov wrote:
> > Quoting James Almer (2024-03-25 22:13:25)
> >> On 3/25/2024 6:02 PM, Andreas Rheinhardt wrote:
> >>> James Almer:
> >>>> I don't mind a function like that being added to simplify future
> >>>> additions, but this API is orthogonal to the frame side data one. It's
> >>>> also used in packets, for example, and right now lavf is using
> >>>> sizeof(AVMasteringDisplayMetadata) because
> >>>> av_mastering_display_metadata_alloc() is not useful.
> >>>>
> >>>
> >>> The API proposed by me is supposed to make API like
> >>> av_mastering_display_metadata_alloc_size() redundant and therefore these
> >>> two additions are not orthogonal.
> >>
> >> Just because there's a frame side data type for MDM does not make the
> >> new alloc function redundant.
> > 
> > The commit message says:
> > 
> >> av_mastering_display_metadata_alloc() is not useful in scenarios where you need to
> >> know the runtime size of AVMasteringDisplayMetadata.
> > 
> > In what scenarios besides side data do you need to know the size of this
> > struct?
> 
> None within our libraries that i can think of, but library users can 
> have scenarios we need to provide for. MDM is a standalone API, so lets 
> not try to make its usability depend on a separate one.
> I'm replacing a helper with a better one, it should not be so controversial.

Breaking API to benefit hypothetical use cases IS a controversial change
in my view.

-- 
Anton Khirnov