Re: [MMUSIC] Possible BUNDLE alternative syntax: explicit m-line for bundled session

Christer Holmberg <> Fri, 21 September 2012 17:26 UTC

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From: Christer Holmberg <>
To: Parthasarathi R <>, 'Lishitao' <>, "'Ejzak, Richard P (Richard)'" <>, "" <>
Date: Fri, 21 Sep 2012 19:26:50 +0200
Thread-Topic: [MMUSIC] Possible BUNDLE alternative syntax: explicit m-line for bundled session
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Subject: Re: [MMUSIC] Possible BUNDLE alternative syntax: explicit m-line for bundled session
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>I agree with Cullen & others that m=bundle does not have consensus. We need
>more discussion and analysis. The current Bundle syntax is designed in a way
>to reuse lot of existing SDP mechanism (Syntax & Semantics). If possible,
>let us try to fix the open issue with the current mechanism before proceeding
>with m=bundle approach.

Feel free to provide input on how you think we can solve that issue :)



-----Original Message-----
From: [] On Behalf Of
Sent: Friday, September 21, 2012 7:21 AM
To: Christer Holmberg; Ejzak, Richard P (Richard);
Subject: Re: [MMUSIC] Possible BUNDLE alternative syntax: explicit m-line
for bundled session

> -----Original Message-----
> From: [] On Behalf
> Of Christer Holmberg
> Sent: Friday, September 21, 2012 3:32 AM
> To: Ejzak, Richard P (Richard);
> Subject: Re: [MMUSIC] Possible BUNDLE alternative syntax: explicit m-line
> bundled session
> Hi,
> >>> m=bundle requires significant extensions to the syntax and also a near
> >>> doubling in the size of the SDP.  It is harder to specify allowed
> >>> combinations of codecs and other options that are normally associated
> >>> with a single m line.
> >>
> >> Please give an example.
> >
> > To specify two types of audio flows with very different characteristics
I would
> normally have separate media lines with separate codec lists and
> One may require DTMF and the other silence suppression in addition to the
> selected (but different)
> > codecs.  We need to keep this characteristic.  We also need a way of
> specifying bandwidth per (old) media line, which is already supported
> separate media lines but requires that something new be defined for
> What about RTCP
> > characteristics?  We certainly want to specify them per (old) media
> >
> > I understand that this can be done with m=bundle, but it requires new
> Why bother if we have something that can work?
> I am not sure it requires new syntax, if you e.g. can use the ssrc
attribute in
> order to map attributes to specific flows.

I would suggest that put the m=bundle proposal in a separate new personal
draft or in the annex of the existing working draft, and
make a comparison for this proposal and the existing proposal. That will
make it more clear.
For the existing proposal, I believe that people are not totally against,
although it has some issues. (the m=bundle proposal also has some issues).


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