Re: [rtcweb] #15: Section 4.8: SSRC signaling

[[e-mail] (Dale R. Worley)]

> From: Martin Thomson <[e-mail]>
> 
> On 22 April 2013 07:04, Magnus Westerlund
> <[e-mail]> wrote:
> > Yes, we will be more explicit that one MUST be able to handle
> > unannounced SSRCs, this is the result of having this sentence:
> > "Use of the "a=ssrc:" attribute is OPTIONAL." If it is optional to use
> > then a receiver must be capable of dealing when they show up unannounced.

> The basic problem is that you don't have an answer that provides you
> with the necessary information.  Even if you could somehow associate
> an incoming packet with an m= line, [...]

My understanding is that associating an incoming RTP packet with an m=
line is a solved problem -- the transport association on which the
packet arrives determines the bundle, and (within all of the currently
active bundling proposals) the payload type tells which m= line within
the bundle.

> [...] you don't have any way to
> determine what identifier the remote side attached to that stream.
> It's also unknown how that stream was grouped prior to being put on
> the network.  This is somewhat important because we expect it to
> happen in a lot of cases.

However, I believe you are correct that knowing which m= line contains
the SSRC does not tell the RtcWeb stream identification.

Dale