[daala] Number of components, is there room for alpha?

[Frédéric Kayser - CryoPNG]

Hello,
I took a peek at the BGP (Better Portable Graphics) http://bellard.org/bpg/ specs and and it turns out the way transparency was added is not really convincing.
Could a still image format based on Daala offer something better at this level? Like a fourth component for alpha that would have its own quality settings and that would be really integrated with the other components (no large independent alpha blob recorded beside the main image).

Cheers
-- 
Frédéric Kayser