Re: [rtcweb] Quick comments on draft-roach-rtcweb-glareless-add-00

Emil Ivov <emcho@jitsi.org> Mon, 13 May 2013 14:33 UTC

Return-Path: <emil@sip-communicator.org>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 9933921F8F4D for <rtcweb@ietfa.amsl.com>; Mon, 13 May 2013 07:33:16 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.299
X-Spam-Level:
X-Spam-Status: No, score=-2.299 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, MIME_8BIT_HEADER=0.3]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pqVcJ-PBlp4E for <rtcweb@ietfa.amsl.com>; Mon, 13 May 2013 07:33:16 -0700 (PDT)
Received: from mail-bk0-x232.google.com (mail-bk0-x232.google.com [IPv6:2a00:1450:4008:c01::232]) by ietfa.amsl.com (Postfix) with ESMTP id E87AF21F940B for <rtcweb@ietf.org>; Mon, 13 May 2013 07:33:13 -0700 (PDT)
Received: by mail-bk0-f50.google.com with SMTP id ik5so2499584bkc.9 for <rtcweb@ietf.org>; Mon, 13 May 2013 07:33:12 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:message-id:date:from:organization:user-agent :mime-version:to:cc:subject:references:in-reply-to:content-type :content-transfer-encoding:x-gm-message-state; bh=O+H+EnDlhjUOxj75ZXxXaXvVaUNvPaq91A4bL0Mv7eA=; b=i2YiO/3xvjSytJOW2h6lJ62310ozjHSLbxgi1f1PejpRJJq5XUPzZ+aJCrSrhjAIFQ Ghdfxwf8IH44onaQ2bU6fX/q2F+Hh+difcIzDYa0Sze/heF0TLz+t+zSoX0OC3xR2KKv 3o8IzV0Df5NjKjgFqlyqBXM35sySicvMaSCPzowSvURuW2j2GA2YNnD5XSNDvnYw/t3t wzlD7yW1vLE+oFuTy/gMWn/kLTbgCStrdMbo/CFtHPdsZJ5kH1uNDLOfrvHozcqqjJ16 6eKAcT/Zg3FzRYTuhdO0hlAV7kTMK6eNVLcJ0VpXe3R+mMpwZVIjvgqyCaaktJYWojzl 7SmQ==
X-Received: by 10.205.38.195 with SMTP id tj3mr5590960bkb.67.1368455592347; Mon, 13 May 2013 07:33:12 -0700 (PDT)
Received: from [192.168.1.119] ([88.203.232.9]) by mx.google.com with ESMTPSA id j8sm2298660bky.17.2013.05.13.07.33.10 for <multiple recipients> (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 13 May 2013 07:33:11 -0700 (PDT)
Message-ID: <5190F9A6.4000904@jitsi.org>
Date: Mon, 13 May 2013 17:33:10 +0300
From: Emil Ivov <emcho@jitsi.org>
Organization: Jitsi
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130328 Thunderbird/17.0.5
MIME-Version: 1.0
To: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
References: <CA+9kkMDWy_Koq0Aun5A330O7OOMt9vimWPNe_uznAQdr0TSfow@mail.gmail.com> <51897B11.60004@nostrum.com> <518AB095.7010401@alum.mit.edu> <518AC143.2010006@nostrum.com> <1447FA0C20ED5147A1AA0EF02890A64B1C2C70B9@ESESSMB209.ericsson.se> <518D6482.2010008@alum.mit.edu> <1447FA0C20ED5147A1AA0EF02890A64B1C2C807D@ESESSMB209.ericsson.se> <518E70A9.7070007@alum.mit.edu> <1447FA0C20ED5147A1AA0EF02890A64B1C2CA23E@ESESSMB209.ericsson.se> <CAPvvaaKwKBmeXYrCNr-8RAcg3ff5WGwXt77TPc4v-xFKpQWTnQ@mail.gmail.com> <5190948A.5070707@ericsson.com>
In-Reply-To: <5190948A.5070707@ericsson.com>
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: quoted-printable
X-Gm-Message-State: ALoCoQlxQgH7PFHiuS/Uaniny0bg3B0qVeyZVNc1i63j1ri9utiAb/JQYxOGo5xOi+f9Bp8eQ3MJ
Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>, "mmusic@ietf.org" <mmusic@ietf.org>
Subject: Re: [rtcweb] Quick comments on draft-roach-rtcweb-glareless-add-00
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 13 May 2013 14:33:16 -0000

Hey Stefan,

On 13.05.13, 10:21, Stefan Håkansson LK wrote:
>> Well the way I remember it SDP O/A was chosen for session negotiation
>> and that other forms of signalling were explicitly left out of the
>> charter.
> 
> I took the result of the discussion and poll at the IETF-84 
> (http://tools.ietf.org/wg/rtcweb/minutes?item=minutes-84-rtcweb.html) as 
> an indication of that SDP O/A should be used for this kind of in-session 
> changes as well.

True, I am not sure we all realized the number of use cases this would
end up encompassing and how we would end up implementing signalling
features into SDP.

>>> In this case either to transmit a new imageattr value
>>
>> imageattr is great as a declarative parameter indicating capabilities:
>> "I can't show more than 720p so there's no point to send me more than
>> that". Using it as a way to switch between thumbnail and HQ videos is
>> not entire impossible but is not particularly efficient either.
> 
> To me it looks like a solution that people might feel inclined towards 
> using.
> 
> But there are others that want to use simulcast, and then pause/resume 
> sending of high and low resolution streams, and that problem is more or 
> less the same when it comes to signaling.
> 
> And even if we omitted the possibility for a receiver to indicate to the 
> sender (via standardized signaling) that it should pause or resume 
> sending, and instead left that up to an API (at sender side) and 
> proprietary signaling, we still have to have some kind of signaling IMO: 
> the sender can not just stop sending RTP packets, there need to be a 
> signal to the receiver so it understands this 

I never implied there should be no signalling. Just that implementing it
all over SDP O/A leads to unforeseen complexities.

RTCP BYE and/or SSRC expiration would be one option here. Custom
signalling another.

Cheers,
Emil

-- 
https://jitsi.org