AP4_AtomFactory only gives 32-bit size to TypeHandler

[fumoboy007]

From lines 752–764 of Ap4AtomFactory.cpp:

default: {
    // try all the external type handlers
    AP4_List<TypeHandler>::Item* handler_item = m_TypeHandlers.FirstItem();
    while (handler_item) {
        TypeHandler* handler = handler_item->GetData();
        if (AP4_SUCCEEDED(handler->CreateAtom(type, size_32, stream, GetContext(), atom))) {
            break;
        }
        handler_item = handler_item->GetNext();
    }

    break;
}

The TypeHandler only gets passed the 32-bit size. :-(

[barbibulle]

That's true. It is a current limitation. However, we've never run into this as an issue in practice, since the only atoms with a 64-bit size we've encountered are 'mdat' atoms for which there's never been a need to have a custom type handler. Do you have a use case where you need to write a custom type handler for atoms larger than 2^32 bytes?

[fumoboy007]

I don’t have a use case for this. I was writing an implementation for #41 and I noticed that custom atoms only get the 32-bit size.

Now that I think about it, a non-mdat atom with size greater than 4 GB wouldn’t really make sense. It would be nice if custom atoms got the 64-bit size too though. Thanks for adding the “enhancement” label.