Subject: [AVT] Comments on draft-clark-avt-rtcpxr-bis-00.txt

From: "Simon Broom" <[email-masked]>
Date: Fri, 29 Jul 2005 16:54:11 +0100

Hi Alan,

I have reviewed your draft on New Parameter Extensions for RTCP XR. This
looks to be a useful extension to the XR reporting mechanism; I just
have a few questions/comments.

Section 3.7
- You include external delay, and external quality metrics; it would be
useful to include 'External Signal Level', 'External Noise Level' and
'External RERL' as well. Having information from both 'ends' of the
connection is useful when making conversational quality predictions.

Section 3.8
- I don't understand why a local endpoint would report information
related to a remote endpoint, especially information that may have
already been reported via RTCP XR. 
- Also, it I'd have thought it would be more useful to report the
speech/noise levels after any level shifts, since this is far more
relevant to perceived voice quality.

Section 3.9
- What is your definition of a 'bridge'?
- In your example, am I correct in my understanding that mid-point
'bridge' sends an XR packet containing estimated values for R-LQ,
R-LQ-ExtIn and R-LQ-ExtOut? Or does it fill in these fields in the
packet sent from Phone B -> Phone A before forwarding it?

Best regards,
Simon

Simon Broom 
Psytechnics 
www.psytechnics.com

Voice and Video Quality Assessment

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