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Re: [AVTCORE] Leap seconds

"Allison, Art" <AAllison@nab.org> Wed, 14 September 2011 17:47 UTC

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From: "Allison, Art" <AAllison@nab.org>
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Subject: Re: [AVTCORE] Leap seconds
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As I understand it the UTC clock will monotonically increase after
January 2017 (no more leap seconds). What happens at 03:14:07 UTC
<http://en.wikipedia.org/wiki/Coordinated_Universal_Time>  on Tuesday,
19 January 2038 (32 bit count overflow) will need to be addressed by
someone, - your guess if any equipment being built today will be in
service then. 

See
http://www.agi.com/downloads/resources/white-papers/Debate-Over-UTC-and-
Leap-Seconds.pdf  for more information.

 

 

Art Allison 
Senior Director Advanced Engineering, Science and Technology 
National Association of Broadcasters
1771 N Street NW
Washington, DC 20036
Phone  202 429 5418
Fax  202 775 4981 
www.nab.org <blocked::http://www.nab.org>  
Advocacy  Education  Innovation 

From: avt-bounces@ietf.org [mailto:avt-bounces@ietf.org] On Behalf Of
Kevin Gross
Sent: Wednesday, September 14, 2011 1:22 PM
To: avt@ietf.org
Subject: [AVTCORE] Leap seconds

 

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

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