Subject: RE: [ippm] Application loss metrics

From: "Geib, Ruediger" <[email-masked]>
Date: Tue, 27 Feb 2007 14:31:17 +0100

Alan,

|There is considerable work within the standards community in the development
|of objective video measurement techniques, much of which is fairly advanced.
|Some of the lead groups include ITU-T Study Group 9 and 12, 
|the ITU-T IPTV Focus Group, the Video Quality Experts Group (VQEG), ATIS, DSL 
|Forum, TM Forum.........  
|Within IETF, AVT have a working group draft -
|draft-ietf-avt-rtcpxr-video-00.txt - which has been under development for
|the last year, this focusses more on the transport of metrics rather than
|defining new video objective techniques.
|
|Objective video quality estimation algorithms are not east to test
|(objectively) and hence the development of test programs and the work of
|comparison with subjective test data often becomes complex.  
|This is one reason that VQEG exists - it provides a testing function that 
|works with many other standards organizations.   
|
|With regard to your specific observations on I/B/P frames - this is
|absolutely considered within the work done by the various ITU 
|groups and ATIS.  One technique that has been defined, discussed across multiple
|standards organizations and is currently being assessed is based on PSNR
|estimation - which is taking into account loss propagation effects through
|the GoP as well as other coding parameters. 

Thanks for the detauled information. I'm not directly involved, so I couldn't 
point out that.

|My recommendation would be that IPPM does not start work in developing
|objective video quality estimation algorithms, as this duplicates work
|already underway in a number of other groups and IPPM may not have the
|expertize in this area.

I didn't suggest that IPPM starts to work on these algorithms. 
I agree with your proposal.

|IPPM may note however that there are some "holes" in the IPPM 
|metrics as they apply to voice and video over IP.  Packet loss often 
|occurs in sparse bursts, for example periods of 5-30% loss that can last for 
|periods of up to several seconds, and IPPM don't have a metric to describe these.

I didn't read it recently, but can't RFC 3357 provide such metrics?

Regards, Ruediger

|Regards
|
|Alan Clark
|Telchemy
|
| 
|
|-----Original Message-----
|From: Geib, Ruediger [mailto:[email-masked]] 
|Sent: Tuesday, February 27, 2007 3:17 AM
|To: [email-masked]
|Cc: [email-masked]
|Subject: RE: [ippm] Application loss metrics
|
|Dear Nagarjuna
|
|your proposal to work on application level quality metrics is 
|allright with
|me. To the best of my knowledge, up to now there's no 
|objective IP TV/video
|conferencing quality measurement based on subjective 
|judgements which would
|correspond e.g. to those models available for telephony services.
|
|Considering bare "frame loss" however may not result in a satisfactory
|judgement of the influence of loss on a streaming application. 
|It does not
|characterise:
|
|- the importance of the frame which was lost within a
|  Group of Pictures. I frames carry full pictures and
|  serve as a reference, P frames serve as a reference,
|  whereas B frames don't serve as a reference to
|  other frames.
|
|- the impact of the frame drop within a Group of
|  Pictures on the error propagation within a group of
|  pictures. If a part of an I frame is lost, all other
|  frames referrring to the lost section will display
|  errouneous information no matter whether they are
|  received correctly or not. On the other side, if
|  just a B-frame is lost, only a single picture
|  is influenced (and not a complete Group of
|  Pictures).
|
|- the different size of frames in terms of IP packets
|  per frame. An I frame may be bigger than a P frame. 
|  Both definitely are significantly bigger than
|  B frames.
|
|For those who aren't familiar with streaming: A Group of 
|Pictures is the
|basic way of tranmistting a compressed picture by one complete 
|picture and a
|set of differential changes to it. Each frame results in an 
|own picture and
|the Group of Picture is:
|
|I - BB - P - BB - P.... until next I. Not all frame types must 
|be present
|(except I frames).
|
|Regards,
|
|Ruediger
|
|-----Original Message-----
|From: Venna, Nagarjuna [mailto:[email-masked]]
|Sent: Tuesday, February 27, 2007 4:43 AM
|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 
|
|
|
|---------------------------------------------------------------
|-------------
|--------------------------------------------------
|Service Quality Matters. Test the performance and quality of 
|your VoIP or IP
|video service at:
|http://www.TestYourVoIP.com
|http://www.TestYourIPVideo.com
|
|---------------------------------------------------
|
|Rüdiger Geib
|
|T-Systems Enterprise Services GmbH
|Systems Integration
|Rüdiger Geib
|Line of Business Networks & Processes
|Senior Consultant
|Deutsche-Telekom-Allee 7, 64295 Darmstadt
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