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Re: 答复: Spec question: precise meaning of PeerState and IceState

From: Harald Alvestrand <harald@alvestrand.no>
Date: Sun, 17 Jun 2012 15:47:21 +0200
Message-ID: <4FDDDFE9.4030908@alvestrand.no>
To: "Sunyang (Eric)" <eric.sun@huawei.com>
CC: "public-webrtc@w3.org" <public-webrtc@w3.org>
On 06/17/2012 03:27 PM, Sunyang (Eric) wrote:
>
> Thanks.
>
> So components means pieces of media stream which request a single 
> address, it does not means the ICE candidates pair,
>
> But we need at least one candidates pair per component, right?
>
> So “connected” means all components have at least one  pair per 
> component who have setup connections between A and B.
>

Yes, that fits my interpretation of the spec.

> *发件人:*Harald Alvestrand [mailto:harald@alvestrand.no]
> *发 送时间:*2012年6月17日19:30
> *收件人:*public-webrtc@w3.org
> *主题:*Re: Spec question: precise meaning of PeerState and IceState
>
> On 06/17/2012 08:33 AM, Sunyang (Eric) wrote:
>
> Hi Uberti:
>
> Note: "new" has been removed, as such a state no longer exists; 
> "waiting"/"gathering" have been merged into "starting", as gathering 
> is not a well-defined state.Note: these represent more or less the 
> most pessimistic view across all the streams. *So “connected” means 
> all components are connected.**
>
>
> *
>
> As I suppose, the components means all usable ICE candidates pairs 
> (local+remote), so I guess “connected” should not mean all components 
> are connected, because we have no reason that PeerConnection should 
> use all the ICE candidates pairs, we should use as few pairs as 
> possible to save the resources. So I think “connected” means 
> components needed by peerconnection  are all connected.
>
> No, that's not what "component" means in this context.
>
> If we have a single RTP session, with RTP + RTCP multiplexed, we have 
> one component.
> If we have a single RTP session, but RTP and RTCP use different ports, 
> we have two components.
> If we have two RTP sessions (one for audio and one for video), and RTP 
> and RTCP use different ports, we have four components.
>
> We need to have at least one working pair connected for each component.
>
> The definition is in RFC 5245 (ICE) section 3:
>
>   Component:  A component is a piece of a media stream requiring a
>       single transport address; a media stream may require multiple
>       components, each of which has to work for the media stream as a
>       whole to work.  For media streams based on RTP, there are two
>       components per media stream -- one for RTP, and one for RTCP.
>
> (this was written pre RTP/RTCP multiplexing, which is RFC 5761, and 
> pre BUNDLE)
>
>                      Harald
>
Received on Sunday, 17 June 2012 13:47:52 UTC

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