Subject: RE: [ippm] Application loss metrics

From: "Alan Clark" <[email-masked]>
Date: Tue, 20 Mar 2007 09:29:49 -0500

Nagarjuna
 
Some concerns of a general nature:
 
(i) The draft is very obviously specifically aimed at video carried over
RTP, and is not a general application related metric as the title and
abstract suggest. The AVT group already have a Working Group draft ..
draft-ietf-avt-rtcpxr-video-00.txt .. which defines metrics related to the
performance of video over RTP transport.   The AVT draft is also being
coordinated with a number of other standards committees.
 
(ii) It is not sufficient to know the proportion of video frames impacted.
If an I frame is impacted the resulting errors will extend through the rest
of the Group of Pictures structure, which can be as long as several seconds,
whereas if a B frame is impacted then the error will only affect one frame.
The AVT draft contains metrics that directly relate to the proportions of I,
B and P video frames that are impaired to address this issue.
 
(iii) Within the IP video community, there is considerable work in the area
of FEC and retransmission for correction of lost packets.   The AVT draft
reports on pre- and post- EC loss rates, loss characteristics at various
protocol layers as well as the I/B/P frame stats mentioned above.  Some of
the key developers of error mitigation technology are involved in the same
standards committees that are developing and reviewing IPTV related metrics
and have hence had the opportunity to review the metrics for suitability in
describing the effectiveness of EC algorithms.
 
My recommendation is to focus IETF's video related metrics work in AVT,
which helps to ensure that any IPTV related metrics are in line with
industry direction as AVT's work is already known to ITU, DSL Forum,
ATIS.......  
 
Regards
 
Alan

 

  _____  

From: Venna, Nagarjuna [mailto:[email-masked]] 
Sent: Monday, February 26, 2007 10:43 PM
To: [email-masked]
Subject: [ippm] Application loss metrics

I have posted an individual draft
(http://www.ietf.org/internet-drafts/draft-venna-ippm-app-loss-metrics-00.tx
t) that describes the application level metrics. These are the same metrics
I have talked about in the San Diego meeting.

Comments and feedback are appreciated.

Thanks,
Nagarjuna 

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