Hi, Ali C. Begen (abegen) wrote:
So, if an SDP from entity X says "a=group:FID" without any specific mid values, would that mean entity X can support group:FID semantics on any media streams? Is this for something like capability negotiation because that line does not mean anything specific (at least to me)?
yes, the section is indeed call Capability Negotiation and was already in RFC3388:
http://tools.ietf.org/html/rfc3388#section-8.3 8.3 Capability Negotiation A client that understands "group" and "mid" but does not want to make use of them in a particular session MAY want to indicate that it supports them. If a client decides to do that, it SHOULD add an "a=group" line with no identification-tags for every semantics it understands. If a server receives an offer that contains empty "a=group" lines, it SHOULD add its capabilities also in the form of empty "a=group" lines to its answer. Cheers, Gonzalo