Re: [MMUSIC] ABNF syntax in 3388bis

["Ali C. Begen (abegen)" <abegen at cisco.com>]

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)?

Thanks,
-acbegen

> -----Original Message-----
> From: Gonzalo Camarillo [mailto:Gonzalo.Camarillo at ericsson.com]
> Sent: Wednesday, November 04, 2009 6:37 AM
> To: Ali C. Begen (abegen)
> Cc: mmusic at ietf.org
> Subject: Re: ABNF syntax in 3388bis
> 
> Hi,
> 
> it needs to be optional so that an implementation can use a group line
> with no identification tags to express its capabilities (i.e., the
> values for grouping semantics it supports). For example, an
> implementation may only support LS and FID but none of the semantics
> extensions defined later.
> 
> Cheers,
> 
> Gonzalo
> 
> Ali C. Begen (abegen) wrote:
> > I have a question about http://www.ietf.org/id/draft-ietf-mmusic-rfc3388bis-03.txt
> >
> > Section 5 of -03 version says:
> >
> >            group-attribute     = "a=group:" semantics
> >                                  *(space identification-tag)
> >            semantics           = "LS" / "FID" / semantics-extension
> >            semantics-extension = token
> >
> > I don't know every detail of the ABNF syntax, but here the identification tags seem to
> be totally optional, whereas we at least need two of them to be able to use the 'group'
> attribute, right?
> >
> > So, should not we rather have:
> >
> >            group-attribute     = "a=group:" semantics
> >                                  2*(space identification-tag)
> >            semantics           = "LS" / "FID" / semantics-extension
> >            semantics-extension = token
> >
> > -acbegen
> >