Re: [rtcweb] codec and connection negotiation

Henry Sinnreich <henry.sinnreich@gmail.com> Wed, 10 August 2011 00:59 UTC

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Date: Tue, 09 Aug 2011 19:59:38 -0500
From: Henry Sinnreich <henry.sinnreich@gmail.com>
To: Bernard Aboba <bernard_aboba@hotmail.com>, pkyzivat@alum.mit.edu
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Thread-Topic: [rtcweb] codec and connection negotiation
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Subject: Re: [rtcweb] codec and connection negotiation
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Leaving all the problems behind mentioned here for SDP (in full agreement),
the bigger picture is that apps may have so many other types of data to
exchange, besides codecs.
For example numbers, sizes and types of screens, keyboard/touch devices to
optimize user experience, data for mashup parts of the screen, say surround
sound(?), etc.
Folks not wedded to SDP use metadata to exchange app info. Why should RTC
continue to inhabit a world of its own, even in the browser?

Naïve question:
Does this separate use of SDP to convey RTC metadata not contradict the
target universality of apps in the browser?

Thanks, Henry


On 8/9/11 12:18 PM, "Bernard Aboba" <bernard_aboba@hotmail.com> wrote:

> Paul Kyzivat said:
> 
>> > Certainly it would be possible to provide an API that had something
>> > semantically equivalent to SDP while using a different syntax. But thata
>> > comes at the price of having to then track future extensions to SDP.
>> > 
>> > An alternative is to profile/subset SDP and then perhaps develop a new
>> > representation semantically equivalent to that. The trouble with that is
>> > interoperation with things that don't fit the subset. Going that way
>> > will probably require making it pretty easy to extend the subset when
>> > things that had been excluded are found to be needed.
>> > 
>> > (It gets worse if you decide to "add a few things" to the API that
>> > aren't part of standard SDP.)
> 
> [BA]  Given the discussion of IETF 81, my concern is that the API is based on
> an SDP and ICE profile that is implicit and not explicit.    In a number of
> cases, it would appear that this implicit profile may ignore normative
> requirements (including MUSTs) in RFC 3264, 5245 and other relevant RFCs.
> 
> The danger in continuing down that road is  that different implementations
> will make different assumptions about the profile, and the result will be
> implementations that are not only incompatible with each other, but also with
> existing implementations of the wire protocols.
>        
> 
> 
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