I'm trying to make a simple 2D animation file format. It'll be very rudimentary: only an XML file containing some parameters (such as frame duration) and metadata, and some images, each representing a frame.

I'd like to have the whole animation (frames and XML document) packed in a single file. How do you suggest I do that? What libraries are there that would allow easy access to the files inside the animation file itself?

The language I'm using is C++ and the platform is Windows, but I'd rather not use a platform dependent library, if possible.