[MMUSIC] Issue with RID draft: support for "pt=" should be optional

Peter Thatcher <pthatcher@google.com> Thu, 22 October 2015 21:19 UTC

Return-Path: <pthatcher@google.com>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 82ADF1B421D for <mmusic@ietfa.amsl.com>; Thu, 22 Oct 2015 14:19:24 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.188
X-Spam-Level:
X-Spam-Status: No, score=-0.188 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FM_FORGED_GMAIL=0.622, HTML_MESSAGE=0.001, J_CHICKENPOX_19=0.6, J_CHICKENPOX_41=0.6, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01] autolearn=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id p1Bc-gnfBnZy for <mmusic@ietfa.amsl.com>; Thu, 22 Oct 2015 14:19:23 -0700 (PDT)
Received: from mail-oi0-x229.google.com (mail-oi0-x229.google.com [IPv6:2607:f8b0:4003:c06::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 64ADC1B421B for <mmusic@ietf.org>; Thu, 22 Oct 2015 14:19:23 -0700 (PDT)
Received: by oifu63 with SMTP id u63so12523027oif.2 for <mmusic@ietf.org>; Thu, 22 Oct 2015 14:19:22 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:from:date:message-id:subject:to:content-type; bh=M/NdTWruOri5bNI8VQ3jUU1TjaAC74MdlHNWeaAY1VI=; b=AtH/OWO8EKTPBuO+xc858JxoFittCLVcqe2FSvvsyXe+wIT4YsThR7UtzaIEmDl5iK WJuUo+F2QOkm5KZ2a5joJW0NuA2q9GvXlSOa2b5nNsdvvpYbcUBX9xJWQiQ0Ub1SeTVd K+fyw9VvPs6eaKFp1TQFZ4tccuB7AWZQeum6dCUxO2viLkYLiDyD3Hql2NhX8/TxZU6t 5eQg7l28hujpeTP1Iod54IigHrw8Oz8crvxCmVpYS7ZITIlnfmmo0B9W0bbvTEuj6VAf zxOB4iT/pG4vqNAxRPN/MQicrh+LaYdHUWcI2U+87uk2gkyRAF3dIQ/dAPV6QvUMw6T8 94jw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:from:date:message-id:subject:to :content-type; bh=M/NdTWruOri5bNI8VQ3jUU1TjaAC74MdlHNWeaAY1VI=; b=ErjsCN77vMYHuH4ohbmcNJ5qtGFyummQK2ytdCTZITk4Y/ZFqcopis/1J9I1q9Rc4H hkB8udK3oi0WR5CGjLLqPOK6ZmeY4LBY0Wj69iHkuZQoEjgciHPKrW9owck0+qiMrrzJ 2HNfw9E9anQiL53wvsy3U9QxIP2DJkY1PLe7s4h7mfSG20NV7ATqpy0Kibc5psuN3VS1 MRAi5sStzGg3YX6U/s7glnX8qZxfMVez4niQaFQbBzbzSgp85wJniHMgz8iKqmeipPJq evkScwZdOhpzWva/iHJPwAsJTkTUs7QepKCq+bEw9J6l8xYm+qj0yrhcyjDDX+oIeT8n la3A==
X-Gm-Message-State: ALoCoQkX5FbOKVi5/hRAkX+m5oiJbW3q7QCCcMjROM3SCs5IWZlCcRCBX2Jon+ITkxdNMVa8pQ6e
X-Received: by 10.202.104.201 with SMTP id o70mr11875894oik.126.1445548761352; Thu, 22 Oct 2015 14:19:21 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.202.79.19 with HTTP; Thu, 22 Oct 2015 14:18:41 -0700 (PDT)
From: Peter Thatcher <pthatcher@google.com>
Date: Thu, 22 Oct 2015 14:18:41 -0700
Message-ID: <CAJrXDUFN6oEh4t5_kKm2fxP_h0HHfGVgnYvmG=RU7Hg23pBs0A@mail.gmail.com>
To: "mmusic@ietf.org" <mmusic@ietf.org>
Content-Type: multipart/alternative; boundary=001a1140978c82d8030522b80c6a
Archived-At: <http://mailarchive.ietf.org/arch/msg/mmusic/IezoXbfXQrLSr5UED5vAn26d7pQ>
Subject: [MMUSIC] Issue with RID draft: support for "pt=" should be optional
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/mmusic/>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 22 Oct 2015 21:19:24 -0000

Currently, all attributes/constraints on an a=rid line are optional.  For
example, if the offer contains this:

a=rid:A send
a=rid:B send
a=simulcast rids:A,B

and the answer contains this:

a=RID:A recv max-fs=15
b=RID:B recv max-fs=15
a=simulcast rids:A,B

That's an error because the offer indicated no support for max-fs.


However, currently in the draft (if I'm reading it correctly), the answer
can contain this:

a=RID:A recv pt=1,2
b=RID:B recv pt=3,4
a=simulcast rids:A,B


This is problematic for two reasons:

1.  It's not consistent with all of the other attributes/constraints.

2.  Like many of the other attributes/constraints (which are optional), pt
doesn't map well to the WebRTC API, which means it will make sense to not
support pt constraints in WebRTC 1.0.  But if it remains mandatory in this
draft, then the draft may end up being incompatible with WebRTC 1.0.


I propose we treat pt= just like max-fs= and max-width=, etc, and make it
optional.  Otherwise we risk ending up with a draft that we can't use for
WebRTC 1.0 anyway.   Plus, it would be more consistent with all the other
attributes/constraints on an a=rid line.