Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP

Peter Thatcher <pthatcher@google.com> Thu, 07 March 2013 21:34 UTC

Return-Path: <pthatcher@google.com>
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 A22E921F85FE for <rtcweb@ietfa.amsl.com>; Thu, 7 Mar 2013 13:34:21 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -101.978
X-Spam-Level:
X-Spam-Status: No, score=-101.978 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, FM_FORGED_GMAIL=0.622, NO_RELAYS=-0.001, USER_IN_WHITELIST=-100]
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 8WLIQrlq3vCN for <rtcweb@ietfa.amsl.com>; Thu, 7 Mar 2013 13:34:20 -0800 (PST)
Received: from mail-vb0-x22c.google.com (mail-vb0-x22c.google.com [IPv6:2607:f8b0:400c:c02::22c]) by ietfa.amsl.com (Postfix) with ESMTP id B20D921F8566 for <rtcweb@ietf.org>; Thu, 7 Mar 2013 13:34:20 -0800 (PST)
Received: by mail-vb0-f44.google.com with SMTP id fr13so373944vbb.17 for <rtcweb@ietf.org>; Thu, 07 Mar 2013 13:34:20 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:mime-version:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=pwHZvuwCzfbzXQi2XG1oBHTrxv+FMsowRTq5MH7AE/Y=; b=W8d8l6+pzOe6Su75rQYvMhALPKhC03ily/hgJUtXFPJ/Ybb1EIecSZ2oE72aQaD1N/ iIvJmU6/2QaVZbu8+E811M2t/C361zsTeKFECDqaDwexRUN+rX9uvV9EN5IX8XPkUODp GY+CgkC3TKg/JkiAjsegrODbCZxpVE4f5W3cVZ4RSunyhkSlH1/xZ+sNk7ZjqKk7Rb6F rYKUNe6gHFTBum6gKodUexxQeK4JQ9E46+2NU6e2dNmVils5su9A85T0j/CLeMa7Rq42 AqNJVGgubpbYFh+yunUlK2ZxdYqRBZc+OJg8iaxFNjblFoYYWfZE1Tn0auGq8gAk1OYH WBGw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:mime-version:in-reply-to:references:from:date:message-id :subject:to:cc:content-type:x-gm-message-state; bh=pwHZvuwCzfbzXQi2XG1oBHTrxv+FMsowRTq5MH7AE/Y=; b=TsajwRTEnBSDdL1b8E1lgpq5Gq34KPglsH/yNA/SQDtz6YSsiSBgRaAd/tHfD3Z+Uf Z9wU1TCHCml2BhShbCrhwmiTz1WgYQXfNPn7VNyh5Mp3YsAnCbC6rLIJEP0KjwHdMqmw Gs/l71ZRjxEUoKmPE0C2Vp5LeSggJulclAiz+s/l1OGaW+3zJz6GF5iitmlMB2C+u8VH yC/EdUSUD6FP4bZKTx7ncqJRIHIyGaF5h+id7s19D3fWTgvACVAgNES6hzZ4AeI4zUe0 4d9fHMDiuIgbwoXvNXD95VszmnSVDUnX0OrNX/ywcj7WeikcBwnXURgGUYtc+amfO5/u T0rg==
X-Received: by 10.52.33.68 with SMTP id p4mr11699627vdi.125.1362692060120; Thu, 07 Mar 2013 13:34:20 -0800 (PST)
MIME-Version: 1.0
Received: by 10.58.49.102 with HTTP; Thu, 7 Mar 2013 13:33:40 -0800 (PST)
In-Reply-To: <CAHp8n2mqQvAcVb3Mc6pbGoCOtPeFG+dRM6BaEVVqpEBZao7N9g@mail.gmail.com>
References: <CD5D3F35.B22B%robin@hookflash.com> <B9549E2E-6E68-4F34-A9C0-1F050285A70A@acmepacket.com> <CABkgnnXCio-Dw7dN5yfSjeRf3wG2oWow_M2mU-Y49TedSAPQmg@mail.gmail.com> <CAHBDyN6CFTix3W9qWgC1T0O36t4SajL3hMXaHOdkat-p5TY_xA@mail.gmail.com> <CABcZeBMLdEkFZq5rMOY0texKb4DtFQ-O86JkC17kJihxv6Dj8w@mail.gmail.com> <CAHBDyN6mM-rT315uSbeTQfKuCiVwsEDhi7Q6DEbt8pjiJ_4i6g@mail.gmail.com> <CAHp8n2nz=NZb=UaevUSS7GRSBpvn-v9_=QHz6iddnZzyx5-TSQ@mail.gmail.com> <CAJrXDUETwfY7ZvaXO_1Bq8gs8pOTgALQE8FiimrUX7sfuEpDsw@mail.gmail.com> <CAHp8n2kcEHcz11LOYYMZ3-nv2PYQKu=z6M=dsQ_H5JuR8ND7hQ@mail.gmail.com> <CAJrXDUF2o0sgTq-f30vRYU0Hrx_bKUkb5eaGkLoE1ysXvfdN7w@mail.gmail.com> <CAHp8n2mqQvAcVb3Mc6pbGoCOtPeFG+dRM6BaEVVqpEBZao7N9g@mail.gmail.com>
From: Peter Thatcher <pthatcher@google.com>
Date: Thu, 07 Mar 2013 13:33:40 -0800
Message-ID: <CAJrXDUEzyd47r13CtA2dTzv+da=jv0=9-1QnLJ0r4t=-Xx_7NA@mail.gmail.com>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Content-Type: text/plain; charset="UTF-8"
X-Gm-Message-State: ALoCoQkqS0/5hC+pwX+wmCtNr074YKb/Gikml/nqEH+m0qScJuR9tCRIOphqi+yv0DGjMbujF3oBSC1IfMqvz+Ag8A3CvYY1nb6/yWcUgiJuqQUYaryhXf+fvpH5OG3qmt4N7Jil++S0DqdvOkiHffXvO2SK6fiLqKLw5qbhZlbEGndtAKih8JZyS9P4lWvLEk4z1/SOmpPa
Cc: "<rtcweb@ietf.org>" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Proposed Plan for Usage of SDP and RTP - Lower level API minus SDP
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: Thu, 07 Mar 2013 21:34:21 -0000

A JSON format doesn't have to be "SDP in a different format".  It can
be much better.  It can expose an easy way to change the video
resolution to send, or a way to add/remove tracks easily.

Listing cameras, however, is a whole different topic.

On Thu, Mar 7, 2013 at 1:30 PM, Silvia Pfeiffer
<silviapfeiffer1@gmail.com> wrote:
> If your suggestion is only to convert the SDP to JSON, then that's a first
> step, but not the full story, because the complexity is just represented in
> a different format. I'm looking for something that helps programmers achieve
> their goals more easily.
>
> JSON is a first step, because it's a more readable data format. However, it
> doesn't help me, to e.g. list the cameras on offer and remove one, or change
> the offered video resolution. That needs manipulation functions.
>
>
>
> On Fri, Mar 8, 2013 at 8:25 AM, Peter Thatcher <pthatcher@google.com> wrote:
>>
>> So, would you like a SessionDescription that is easy to read and
>> manipulate, such as a JSON object?
>>
>> On Thu, Mar 7, 2013 at 1:22 PM, Silvia Pfeiffer
>> <silviapfeiffer1@gmail.com> wrote:
>> > Agreed, but it's also not sufficient. SDP is not "programmer friendly"
>> > enough because it has too many details that are protocol-details only
>> > and
>> > it's too hard to see the semantic bits in SDP and ignore the rest.
>> >
>> > For example: the programmer wants to say - I want to get this video
>> > resolution, this audio bitrate & channels, I want to use this camera and
>> > this microphone for this call. Having to manipulate SDP directly for
>> > this is
>> > a programmer's nightmare.
>> >
>> > Silvia.
>> >
>> >
>> > On Fri, Mar 8, 2013 at 8:12 AM, Peter Thatcher <pthatcher@google.com>
>> > wrote:
>> >>
>> >> You can already do that by "munging" the SDP.  It's just not very
>> >> pleasant to do.
>> >>
>> >> On Thu, Mar 7, 2013 at 1:09 PM, Silvia Pfeiffer
>> >> <silviapfeiffer1@gmail.com> wrote:
>> >> > On Fri, Mar 8, 2013 at 5:51 AM, Mary Barnes
>> >> > <mary.ietf.barnes@gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> On Thu, Mar 7, 2013 at 12:42 PM, Eric Rescorla <ekr@rtfm.com> wrote:
>> >> >> >
>> >> >> > On Thu, Mar 7, 2013 at 9:56 AM, Mary Barnes
>> >> >> > <mary.ietf.barnes@gmail.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> On Thu, Mar 7, 2013 at 11:43 AM, Martin Thomson
>> >> >> >> <martin.thomson@gmail.com> wrote:
>> >> >> >> > Obviously I (and my employer) agree with these sentiments
>> >> >> >> > wholeheartedly.  Both Robin and Hadriel.
>> >> >> >> >
>> >> >> >> > That doesn't change the fact that a number of people are highly
>> >> >> >> > motivated to protect their investment in SDP offer/answer.  For
>> >> >> >> > those
>> >> >> >> > people, the pain that causes everyone else is clearly far less
>> >> >> >> > important than the pain they feel at this moment.  So here we
>> >> >> >> > are.
>> >> >> >>
>> >> >> >> [MB] I originally thought that either approach could work.  I did
>> >> >> >> see
>> >> >> >> the value that folks saw in using SDP offer/answer. But after
>> >> >> >> sitting
>> >> >> >> through the interim meeting last month, I am very much of the
>> >> >> >> mindset
>> >> >> >> that using SDP O/A is a bad idea.   I think many of us thought
>> >> >> >> that
>> >> >> >> using the SDP blob would help with interoperability with "legacy"
>> >> >> >> SIP
>> >> >> >> endpoints.  I don't see that now at all.  I think we will end up
>> >> >> >> with
>> >> >> >> a very fragile solution that will be very difficult to
>> >> >> >> extend/modify
>> >> >> >> later if we continue down the SDP O/A path.
>> >> >> >> [/MB]
>> >> >> >>
>> >> >> >
>> >> >> > Hasn't the WG already been asked this question not once but
>> >> >> > twice.
>> >> >> [MB] Yes.  And, some of us have changed our positions based upon the
>> >> >> challenges that the group is facing in getting the current approach
>> >> >> specified and agreed.  I don't disagree that it is not a good thing
>> >> >> that this is being discussed yet again.  [/MB]
>> >> >
>> >> >
>> >> > [Gotta love the triple negation!]
>> >> >
>> >> > Why can't we have it both ways?
>> >> >
>> >> > Maintain the current way to get the raw SDP using createOffer, but
>> >> > then
>> >> > provide an interface to change that offer before setLocalDescription.
>> >> >
>> >> > Even CISCO provides such an API:
>> >> >
>> >> >
>> >> > http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/sip_tn/8_5_1/4-sdp_api.html
>> >> > (I think we can do a better one than this, but it's a reference
>> >> > point).
>> >> >
>> >> > Cheers,
>> >> > Silvia.
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > rtcweb mailing list
>> >> > rtcweb@ietf.org
>> >> > https://www.ietf.org/mailman/listinfo/rtcweb
>> >> >
>> >
>> >
>
>