[xiph-rtp] header ident decision

[Aaron Colwell]

On Mon, May 02, 2005 at 10:57:31PM +0100, Phil Kerr wrote:
> Ralph Giles wrote:
> 
> >On Sun, May 01, 2005 at 09:52:56AM -0700, Ralph Giles wrote:
> >
> > 
> >
> >The server MUST ensure that the setup ident field in the payload header 
> >attached to any ident or setup header packets is a consistent and unique 
> >mapping within an RTP session, so that clients can safely discard such 
> >packets if they already have a decode setup for that ident field.
> > 
> >
> Because the Ident field is freeform (not derived from the stream itself 
> using crc32) you will lose caching.

You can still have caching. You just need the ident -> chainID and 
codebook -> chainID mappings conveyed out of band or at least have a
base URL that you can use to grab the mapping information. This info can be
conveyed via SDP. 

I suppose the base URL and/or chain ID to codebook/ident hashs could be 
transmitted inline as well. That info should be pretty low BW.

Aaron