WebRTC CreateOffer analysis
The purpose of 1. CreateOffer
WebRTC is mainly used for audio and video communication between peer, and former communications need to negotiate a number of parameters, such as codecs, transport protocols.
So CreareOffer's purpose is to collect locally relevant parameters used to initialize a session.
2. CreateOffer mainly gathered what information
. a What you want to transfer: the media-related information, primarily audio, video, data, and the corresponding parameters supported;
b how transmission: That transfer address, policies, agreements;
How to exchange 3. Offer
Offer and WebRTC in the corresponding SDP Answer are exchanged by using a signaling server.
SDP: Session Description Protocol SDP, is widely used to describe multimedia sessions in the session information, which defines the specification, the semantics of the session description do not limit the transport layer protocol.
Since the SDP protocols need to support a variety of heterogeneous terminal (such as PC, telephone, etc.), heterogeneous network, heterogeneous systems, so its usage scenarios and interactive define quite complex, it is recommended to understand the basic specification: RFC4566
Annex: WebRTC in, at each SDP interactive example scenario: the WebRTC the SDP