Re: [rtcweb] Proposal for PeerConnection cloning

Randell Jesup <> Mon, 07 May 2012 21:54 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 8A88421F846A for <>; Mon, 7 May 2012 14:54:22 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.374
X-Spam-Status: No, score=-2.374 tagged_above=-999 required=5 tests=[AWL=0.225, BAYES_00=-2.599]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id HdxW4S2mKjP8 for <>; Mon, 7 May 2012 14:54:21 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id A086C21F843E for <>; Mon, 7 May 2012 14:54:21 -0700 (PDT)
Received: from ([] helo=[]) by with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.69) (envelope-from <>) id 1SRVsq-0000hu-LD for; Mon, 07 May 2012 16:54:20 -0500
Message-ID: <>
Date: Mon, 07 May 2012 17:53:10 -0400
From: Randell Jesup <>
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20120420 Thunderbird/12.0
MIME-Version: 1.0
References: <> <>
In-Reply-To: <>
Content-Type: text/plain; charset="windows-1252"; format="flowed"
Content-Transfer-Encoding: 7bit
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname -
X-AntiAbuse: Original Domain -
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain -
Subject: Re: [rtcweb] Proposal for PeerConnection cloning
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 07 May 2012 21:54:22 -0000

On 5/7/2012 5:32 PM, Harald Alvestrand wrote:
> Richard, thank you for doing this! It's definitely the most
> thought-through proposal I've seen on this question!


>>  5. The CPC object will inherit the local streams, local ICE
>>     candidates, and local description of the PC.
> when it inherits the local streams, do you assume that unless the JS
> applies some setting, they will also inherit the "enabled/disabled"
> state, but that the "enabled/disabled" state can be changed
> independently for each PeerConnection's local streams after the cloning?

I would assume that personally, and that typically after cloning you'd 
do "appropriate" tweaking to new (and old).

>>  8. The local streams might multicast toward the remote targets
>>     depending on the directionality attributes independently set for
>>     each PC and clone.
> So far, we've stayed away from anything that involves IP multicast. Are
> you sure it's worth the potential complexity to try to use this here?

Richard - do you mean "IP Multicast" (tm) or 'multicast' by sending the 
same encoded data to more than one destination in separate RTP streams? 
  (i.e. one encoding being used to simulcast to multiple receivers?)

Simulcast is possible and useful (almost required for Mesh 
Conferencing); IP Multicast has been pretty much ruled out-of-scope IIRC.

Randell Jesup