AVIF metadata is improperly marked as private

[amyspark]

Hi,

Coming here from image-rs/image#2892, I noticed that mp4parse can be just enough for initializing an image decoder before the images are actually requested. However, several structs are marked as private, making them unusable:

• NclxColourInformation
• ImageMirror
• PixelAspectRatio
• ImageSpatialExtentsProperty (critical)

Would it be possible to expose these appropriately, and if necessary, via a copyable or borrowed fully public struct?

[Shnatsel]

Background: this is of interest for using image-rs and by extension mp4parse-rust in GStreamer.

[amyspark]

Looking at cbindgen's output:

This tells me that the crate itself may not have been tested outside of the C bindings, as cbindgen is breaking the visibility rules of the underlying Rust type (struct fields are private unless marked as pub).

[kinetiknz]

We only consume this crate via the C bindings, so we've never given much thought to public Rust interface. We're happy to take patches to expose more via the public Rust interface if it makes the crate more useful to you.

[amyspark]

I have a working implementation to expose these atoms, however to finish it I need a way to access the item property boxes, where the Exif and XMP metadata lay. Would it be OK with you if I move some things around to expose them in the AvifContext @kinetiknz?

[kinetiknz]

Yeah, that should be fine. Thanks for working on this!