Subject: RE: [Speermint] Speermint] requirements: codec

From: "Jean-Francois Mule" <[email-masked]>
Date: Wed, 13 Sep 2006 16:40:51 -0600

Daryl wrote:
> I don't think RTCP should be mandatory, as there are arguably better
> methods for monitoring audio quality.  
I was actually surprised this comment did not come up before, in the first round of comments. RFC 3550 has a SHOULD on the actual use of RTCP for the 3 main functions.

> Some of these include a
> combination of ITU-T P.862 and P.563.  From my perspective, RTCP does
> not help us identify much of anything.  For example, RTCP may tell you
> their is a delta between packets sent and received, but it will not
> tell
> you where the problem occurred, and whether or not it actually
> affected the audio quality.
The VoIP metric block of RFC 3611 (conveyed via RTCP XR) attempts to help that diagnosis, no?

We need more opinions on the level of requirement on the RTCP use in speermint (not its support, just to avoid the TLS ambiguities we had).

> I agree with the rest of your assertion.  Thanks for compiling the
> results...--Daryl

Ok thanks.

Jean-François

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From: Daryl Malas <[email-masked]>
Date: Thu, 14 Sep 2006 16:06:47 -0600

I need to review 3611 again before I comment too far, but if my memory
serves me right; 3611 defines a subjective way of using RTCP information
to estimate audio quality.  It still has the same root problems that
RTCP has as I described previously.

RTCP can be used for trending "quality" performance, but is not precise
in implying a troubleshooting path to problem resolution; especially if
the problem is sporadic.  Since, it simply doesn't provide any clear
indication as to whether an audio quality problem truly exists or not,
and if it actually does...where the problem exists; I suggest this is
definitely NOT a requirement for peering.

Following that note...some Operators don't use RTCP at all, using P.862
or P.563 methods instead.  Some are using a hybrid solution.  Like
CODECs, this will likely be negotiated between peers and should not be a
MUST.  I don't know of anyone using RTCP-XR (which I'm sure someone will
blast me on) in the industry yet; or has plans to in the future.

--Daryl