Re: [MMUSIC] BUNDLE/SDP : ISSUE#2: Should BUNDLE allow/disallow SSRC Repetition ?

[Harald Alvestrand <[e-mail]>]

A=ssrc attributes are a class, so a single rule is likely not enough.
Suggest NORMAL as default with a note that individual attributes may be
designated SPECIAL or identical.
31. okt. 2013 08:31 skrev "Magnus Westerlund" <
[e-mail]> følgende:

> Hi,
>
> See inline on my opinion and thinking around this subject.
>
> On 2013-10-31 05:46, Suhas Nandakumar wrote:
> > Hello All
> >
> >   Another issue or concern that was brought up is dealing with RFC5576
> > SSRC attributes across the BUNDLED m=lines.
> >
> > RFC5576 does allow SSRCs to be repeated across the m=lines given that
> > each m=line forms a separate RTP Session.
> >
> > There were two options suggested in this regard (by Jonathan)
> >
> > 1. Don't allow SSRC values to be repeated across the bundled m-lines
> >     ==> Assign category NORMAL
> >
>
> Although it will be normal that a specific SSRC value will only be
> associated with a specific media description (m= block) there are
> counter arguments for why this limitation can't be done.
>
> For example an FEC encoding across multiple SSRCs i.e. RTP packet
> streams can be sent in the same RTP session under its own SSRC. That
> SSRC may be desirable to reference in all the m= blocks that contributes
> to this particular encoding. Note, we really are talking about
> referencing the same packet stream from multiple places.
>
> There are likely more cases where this type of need will arise.
>
> > 2. Allow SSRC values to be repeated iff the media stream satisfies more
> > than one m=lines, in which case, the individual sources define the
> behavior
> >   ==> We have 3 options here
> >    2.1 Assign Category SPECIAL and add explanatory note on possible
> > scenarios
> >
>
> I think this is likely sufficient to solve this case.
>
> >    2.2 Assign Category SPECIAL and propose an update to RFC5576 to
> > explain behavior of a=ssrc attributes when multiple m=lines are
> multiplexed
> >
> >    2.3 Define a new category ??
> >
> >
> > I look forward for your inputs on how do we deal with this issue.
>
> Cheers
>
> Magnus Westerlund
>
> ----------------------------------------------------------------------
> Multimedia Technologies, Ericsson Research EAB/TVM
> ----------------------------------------------------------------------
> Ericsson AB                | Phone  [phone]
> Färögatan 6                | Mobile [phone]
> SE-164 80 Stockholm, Sweden| mailto: [e-mail]
> ----------------------------------------------------------------------
>
>