IETF Logo Mail Archive

[AVTCORE] Leap seconds

Kevin Gross <kevin.gross@avanw.com> Wed, 14 September 2011 17:20 UTC

Return-Path: <kevin.gross@avanw.com>
X-Original-To: avt@ietfa.amsl.com
Delivered-To: avt@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 6BA0521F8B9D for <avt@ietfa.amsl.com>; Wed, 14 Sep 2011 10:20:12 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: 1.027
X-Spam-Level: *
X-Spam-Status: No, score=1.027 tagged_above=-999 required=5 tests=[AWL=-1.514, BAYES_40=-0.185, FH_RELAY_NODNS=1.451, FM_FORGED_GMAIL=0.622, HELO_MISMATCH_COM=0.553, HTML_MESSAGE=0.001, RDNS_NONE=0.1]
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 UMDcuNNUsGXK for <avt@ietfa.amsl.com>; Wed, 14 Sep 2011 10:20:11 -0700 (PDT)
Received: from oproxy1-pub.bluehost.com (oproxy1.bluehost.com [IPv6:2605:dc00:100:2::a1]) by ietfa.amsl.com (Postfix) with SMTP id 67E4621F8783 for <avt@ietf.org>; Wed, 14 Sep 2011 10:20:11 -0700 (PDT)
Received: (qmail 29967 invoked by uid 0); 14 Sep 2011 17:22:20 -0000
Received: from unknown (HELO host291.hostmonster.com) (74.220.215.91) by oproxy1.bluehost.com with SMTP; 14 Sep 2011 17:22:20 -0000
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=avanw.com; s=default; h=Content-Type:To:From:Subject:Message-ID:Date:MIME-Version; bh=VGa3EIk+gA8xowciDfXuKUrgutAWaHnAkv4HQO5eXOs=; b=a5VX3Fh/Ost5iLC09WJiJTK12ocfV1IDSUORNdSJzVQHQVFVf93xy6KK/s3EMdDU6stpZCH9imQPc8kUj8yjKqlbwMa9R/nYOmbeynDF2APJRsNpK3taH2+jXbOxvJ1/;
Received: from mail-ey0-f172.google.com ([209.85.215.172]) by host291.hostmonster.com with esmtpsa (TLSv1:RC4-SHA:128) (Exim 4.76) (envelope-from <kevin.gross@avanw.com>) id 1R3tAC-0000F3-Gq for avt@ietf.org; Wed, 14 Sep 2011 11:22:20 -0600
Received: by eye4 with SMTP id 4so1190470eye.31 for <avt@ietf.org>; Wed, 14 Sep 2011 10:22:19 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.223.46.90 with SMTP id i26mr113395faf.83.1316020939010; Wed, 14 Sep 2011 10:22:19 -0700 (PDT)
Received: by 10.223.93.202 with HTTP; Wed, 14 Sep 2011 10:22:18 -0700 (PDT)
Date: Wed, 14 Sep 2011 11:22:18 -0600
Message-ID: <CALw1_Q0qK1WDc_KjEneOWrqr+jfVsqdwFYpF=ht-tS4SSNp8nQ@mail.gmail.com>
From: Kevin Gross <kevin.gross@avanw.com>
To: avt@ietf.org
Content-Type: multipart/alternative; boundary="00151747359a9630c904acea00c9"
X-Identified-User: {1416:host291.hostmonster.com:avanwcom:avanw.com} {sentby:smtp auth 209.85.215.172 authed with kevin.gross@avanw.com}
Subject: [AVTCORE] Leap seconds
X-BeenThere: avt@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Audio/Video Transport Core Maintenance <avt.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/avt>, <mailto:avt-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/avt>
List-Post: <mailto:avt@ietf.org>
List-Help: <mailto:avt-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/avt>, <mailto:avt-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 14 Sep 2011 17:20:12 -0000

I am working on a means of using an IEEE 1588 timebase for RTP streaming. I
am aware of IEEE 1733 and will use that if necessary. First I am exploring
using existing NTP mapping function in RTCP sender reports. While
researching how to translate a 1588 timestamp to its NTP equivalent, I was
reminded of the wrinkle leap seconds put into things.

The RTCP sender report maps RTP timestamps to NTP timestamps. RTP timestamps
are monotonically increasing. The RTP timestamps are based on UTC and have
an occasional wobble due to leap seconds. During the leap second, there is
an ambiguous mapping between RTP and NTP/UTC. I find no recommendations in
RFC 3550 for dealing with this.

-- 
Kevin Gross
AVA Networks
+1-303-447-0517

v2.23.0 | Report a Bug | By Email