[xiph-rtp] Chaining Theora codebook changes

[David Barrett]

Hi, I'm still getting up to speed on the topic so please forgive my
ignorance, but does "chaining" mean "changing codebooks on the fly"?
If so, what is the latest proposal on this?

Looking over the archive, it sounds like:

- The server CAN specify one or more codebooks URLs in SDP
- The server CAN specify new codebooks at will inline
- The server CAN change codebooks at will, and the client MUST accept

Are these statements true?

I know the precise language and syntax are in flux, but it sounds like
each packet will have some kind of variable-length codebook
identifier, effectively choosing from the codebooks predefined by the
SDP.  Is this true?  Can I further choose not only from those defined
in the SDP at the start, but those delivered inline since?

Next, are there any restrictions on what can change with the
codebook?  Can I change framerates, bitrates, resolutions -- basically
anything I want to change?

Finally, if I have a stream that starts with codebook A, switches to
B, and then switches back to A, is it assumed that A picks up "where
it left off", or do I reset the encoder with codebook A?  Is switching
codebooks (assuming I don't need to re-download them) an expensive
operation?

Thanks for your clarifications; just trying to make sure I have my
assumptions in line so I don't march myself into a corner down the
road.

-david