Re: [rtcweb] Signalling, SDP, and the way we think about interconnecting RTCWEB applications

Wolfgang <wolfgang.beck01@googlemail.com> Mon, 17 October 2011 06:14 UTC

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Date: Mon, 17 Oct 2011 08:14:25 +0200
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From: Wolfgang <wolfgang.beck01@googlemail.com>
To: Randell Jesup <randell-ietf@jesup.org>
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Subject: Re: [rtcweb] Signalling, SDP, and the way we think about interconnecting RTCWEB applications
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On Mon, Oct 17, 2011 at 5:34 AM, Randell Jesup <randell-ietf@jesup.org>; wrote:
> On 10/16/2011 4:39 AM, Wolfgang wrote:
>> So why do we transport some codec parameters outside the media stream
>> at all? The called device might need information about the media
>> stream before establishing it.
>
> Exactly, and the media stream is unreliable.  This is the purpose of
> sprop-parameter-sets in H.264 SDP.  Also think of gatewaying rtcweb to SDP.
>
>> The server might need access to codec parameters to forward the call
>> to the best destination: imagine a user with two RTCWEB clients, one
>> only supports only low resolution video, the other one full HD. A high
>> resolution video call comes in. How should the server select the
>> called client if it doesn't have access to the media stream which
>> carries the resolution parameters?
>
> I'm not certain how "the server" would select the client in your scenario
> under any usage; how would the server know before forwarding the call which
> client supported the incoming call's parameters?
That's a valid point. So you think Radhika's proposal to only
negotiate codec types
but not codec parameters in the signaling path would cover all
realistic use cases?

>> In my model the server would know what type of call was set up as it
>> always controls both ends of the call. If some other application
>> controls the calling party, you need some standardized protocol like
>> SDP.
>
> So the server negotiates the parameters?  I'm not sure what "my model" means
> here (and I reviewed earlier messages from you here).
I didn't have company email access during the weekend and I'm the author of
https://datatracker.ietf.org/doc/draft-beck-rtcweb-alt-ic/. The idea
is to always use
only one RTCWEB server and authenticate/authorize unknown users by 3rd party
authentication. Like commenting on a blog using OpenID.



Wolfgang Beck
>
>
> --
> Randell Jesup
> randell-ietf@jesup.org
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>