[rtcweb] On ptimes and maxptimes

Justin Uberti <juberti@google.com> Wed, 05 March 2014 16:27 UTC

Return-Path: <juberti@google.com>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 1DCDE1A0760 for <rtcweb@ietfa.amsl.com>; Wed, 5 Mar 2014 08:27:22 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.725
X-Spam-Level:
X-Spam-Status: No, score=-0.725 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_15=0.6, J_CHICKENPOX_18=0.6, RP_MATCHES_RCVD=-0.547, SPF_PASS=-0.001] 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 sumjaOix0Qru for <rtcweb@ietfa.amsl.com>; Wed, 5 Mar 2014 08:27:21 -0800 (PST)
Received: from mail-ve0-x233.google.com (mail-ve0-x233.google.com [IPv6:2607:f8b0:400c:c01::233]) by ietfa.amsl.com (Postfix) with ESMTP id C40A31A01D8 for <rtcweb@ietf.org>; Wed, 5 Mar 2014 08:27:20 -0800 (PST)
Received: by mail-ve0-f179.google.com with SMTP id db12so1264465veb.24 for <rtcweb@ietf.org>; Wed, 05 Mar 2014 08:27:17 -0800 (PST)
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=zKIdRqnwCH04JVF3cBzI77J048NhQ8ju8CeXIo91SSY=; b=EKeNIPYW3M1I3rGixIH0xR1dQsFdZ/IRwqZLQNC5t7ekAH8QOC41c7AXxn7+03gTGL ZeWBn/Scx5PYWLBJFdZR2vK4pgDoaa9D/ysXEiYsHw0/SaJ/E0VubtMbVYSh2Bj6Ww2U mnF4h8mHs9tYYf2D4TilWLWrpZzDCO8OEWIw2sr//RbJNmG8zi3XiT5qiobCox7hFbHO +EM1JEJO+XPxbJ82euaIwaAhQrU3UTX0CRSVv694qXAPHrE9PImBeFha7CLIwy9gEulQ A9y2IbkmFubTNDph7HBXVnARGFQV7bMDxLycByaQZyFr7U+mMQ8GVWfkGIywHsI4Eon9 5Skg==
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=zKIdRqnwCH04JVF3cBzI77J048NhQ8ju8CeXIo91SSY=; b=GwB8EmxApLkTw3tQWrAbBGCzLhQyEwXdtyJu9bAyUfgh78x5w0pxDoJ/L88RcxtBTM 9jKSSZat2ooyf8+7SOM429u8Hc/SZs/5rFxaSp1yx7S+UHLWTGtvu9LxSGM9Nr0JjE6C MClCkdLAIrVId2a/AHjVAAfaQOAwXyqh1OD1dFKYvEXtarnZ5yzdXyuAjhz6OaNlNknb 8WDDFmAOVei8oz7p5kYOwqM/Q2D+gux+trSZnUIfhNdZVA4WRIYQJuBZGYhjhW/5DW7W X7x7HQDZfe6nQojXUS5wa300JYXThPTrKtYFVldBjraL4RBMN4vICxJs+I+d8+qHcofM KUVw==
X-Gm-Message-State: ALoCoQlgxWNjr20POCRHOZxXNzvsKI1arlhVoB09zSXyJDFJisdwJJBEymj2+HI//8X6UbfDrtL41BZuI2T6p6u0hHmgiRBmJVnIGbukA8tCAotTwEV4/IpiBXhy/yOAqX6AglJq9kahwr0yBVoCpsVyfaYwO6C7ZeDW3a6dr3KqPaAIh08ERtF/ErxQz3f3xpFEYpOIqYz+
X-Received: by 10.221.40.10 with SMTP id to10mr717002vcb.22.1394036836971; Wed, 05 Mar 2014 08:27:16 -0800 (PST)
MIME-Version: 1.0
Received: by 10.52.26.43 with HTTP; Wed, 5 Mar 2014 08:26:56 -0800 (PST)
From: Justin Uberti <juberti@google.com>
Date: Wed, 5 Mar 2014 16:26:56 +0000
Message-ID: <CAOJ7v-1e+FXQZrvh8Q549kwyhf8JX2BA_0q=+6mjha9+o-Dgpw@mail.gmail.com>
To: "rtcweb@ietf.org" <rtcweb@ietf.org>
Content-Type: multipart/alternative; boundary=001a1133757678c54c04f3de7e6c
Archived-At: http://mailarchive.ietf.org/arch/msg/rtcweb/-530QfcgrLwwTFV0v4XBA9ydu08
Subject: [rtcweb] On ptimes and maxptimes
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.15
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: Wed, 05 Mar 2014 16:27:22 -0000

>From the session this morning, I recall this consensus:

   - We will add recommendations on the frame sizes to use for PCMU/A to
   the rtcweb audio codec I-D (20, 30, 60 ms frames).
   - We will consider adding an a=maxptime attribute that represents the
   "minimum maxptime" of all the offered codecs. That is, if both Opus
   (maxptime of 120ms) and PCMU (maxptime of 60) are offered, a maxptime=60
   SHOULD be included.
      - Since maxptime spans all codecs, this means that some modes (e.g.
      Opus 120ms) will be unavailable, unless only Opus is offered.
   - We will consider adding an a=ptime attribute, set to the receiver's
   preferred frame size to receive. Again, this value spans all codecs, so the
   specified value may not be viable for all codecs (e.g. 30 ms works for PCMU
   but not for Opus)

After thinking about this some, I'm not sure the maxptime/ptime values will
lead to any different behavior than if they were not specified. Since there
is a complexity cost (especially if the values need to change based on
which codecs are offered), is there a clear upside here?