[AVT] RE: [AVT] Uncertain about timestamp usage in RFC 2833 named event

["Steve Lubbs" <s.lubbs@ieee.org>]

Hi Dave,
Many thanks for the quick reply. The news about the Cisco upgrade is
particularly helpful.

Regards,
Steve Lubbs

> Steve, I had this same question a while back and I think the consensus
> is your first interpretation, with the timestamp corresponding to the
> beginning of the event and the duration incrementing until the event
> finishes.
> 
> Also, with regards to the Cisco phone, I had a couple of SIP phones
> that I sniffed a while back, booting with a fairly old IOS, and I saw
> the behavior you saw--the timestamp was incrementing while the duration
> was constant. However, when I upgraded the IOS for both phones to the
> most recent one available on the Cisco site, I saw the correct
> behavior--same timestamp, but cumulative duration.
> 
> David Wong
> Software Engineer
> Communications Infrastructure Test Group
> 
> p| 978.661.1241 f| 978.988.0148
> email | dwong@empirix.com
> 205 Lowell Street | Wilmington, MA | 01887
> 
> E M P I R I X
> http://www.empirix.com
> 
> 
> 
>   > -----Original Message-----
>   > From: Steve Lubbs [mailto:s.lubbs@ieee.org]
>   > Sent: Thursday, October 03, 2002 12:54 PM
>   > To: avt@ietf.org
>   > Subject: [AVT] Uncertain about timestamp usage in RFC 2833 
>   > named events
>   > 
>   > 
>   > Hi Folks,
>   > I am in a bit of a quandry related to how the timestamp for 
>   > RFC 2833 named
>   > events should be implemented. My interpretation of the RFC 
>   > is that the
>   > timestamp marks the start of the event and that this same 
>   > timestamp value is
>   > used in all subsequent packets associated with the event. 
>   > Further, the
>   > duration value is cumulative and increases with each 
>   > subsequent packet
>   > associated with the event.
>   > In order to confirm my interpretation I investigated the 
>   > behavior of some
>   > existing implementations. Some, such as MS Messenger and 
>   > OpenPhone, appear
>   > to agree with my interpretation. Others, notably a product 
>   > from Cisco,
>   > don't. The Cisco implementation appears to increment the 
>   > timestamp for each
>   > subsequent packet and keeps the duration constant. This is 
>   > the behavior I
>   > would have expected for RFC 2833 tones.
>   > 
>   > My question is simple. Which interpretation is correct?
>   > 
>   > Regards,
>   > Steve Lubbs
>   > 
>   > 
>   > _______________________________________________
>   > Audio/Video Transport Working Group
>   > avt@ietf.org
>   > https://www1.ietf.org/mailman/listinfo/avt
>   > 


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