[FFmpeg-devel] [PATCH 1/6] avutil/frame: add av_frame_remove_side_data_changed

[Niklas Haas]

On Fri, 26 Apr 2024 16:29:03 -0300 James Almer <jamrial at gmail.com> wrote:
> On 4/26/2024 9:27 AM, Niklas Haas wrote:
> > From: Niklas Haas <git at haasn.dev>
> > 
> > Many filters modify certain aspects of frame data, e.g. through resizing
> > (vf_*scale* family), color volume mapping (vf_lut*, vf_tonemap*), or
> > possibly others.
> > 
> > When this happens, we should strip all frame side data that will no
> > longer be correct/relevant after the operation. For example, changing
> > the image size should invalidate AV_FRAME_DATA_PANSCAN because the crop
> > window (given in pixels) no longer corresponds to the actual image size.
> > For another example, tone-mapping filters (e.g. from HDR to SDR) should
> > strip all of the dynamic HDR related metadata.
> > 
> > Since there are a lot of similar with basically similar operations, it
> > make sense to consolidate this stripping logic into a common helper
> > function. I decided to put it into libavutil as it may be useful for API
> > users as well, who often have their own internal processing and
> > filtering.
> 
> Maybe instead of "changed", which is a concept that doesn't belong to a 
> frame but to a process, use a name that references side data that 
> depends on specific properties (dimensions, color props, etc).
> 
> Also, don't make it depend on AVFrame, but AVFrameSideData instead, so 
> it can be reused in other contexts (Use the av_frame_side_data_* 
> namespace for it).

Do you have a proposed name?

I can think of:
- av_frame_side_data_remove_aspect()
- av_frame_side_data_remove_dependent()
- av_frame_side_data_remove_category()

Not sure if I like any more (which is why I went with _changed(), which
tells you exactly when this function was intended to be used).