Subject: [AVT] Sound Level Indicators

From: Emil Ivov <[email-masked]>
Date: Mon, 15 Jun 2009 16:35:10 +0200

Hi all,

We have just submitted the following draft:

http://www.ietf.org/internet-drafts/draft-ivov-avt-slic-00.txt

The draft proposes a solution for a problem that's been extensively
discussed on the dispatch mailing list during the past few weeks. It
concerned a means of transporting sound level in conferences in a way
that would allow presenting it to the user and extending the active
speaker concept.

We are looking forward to hearing any comments and would especially
appreciate suggestions about how to address the open issues listed in
the last section of the draft.

Cheers
Enrico and Emil

---

From: Colin Perkins <[email-masked]>
Date: Fri, 19 Jun 2009 16:46:01 +0100

> that would allow presenting it to the user and extending the active

I haven't been following dispatch, but this looks like a good use of  
the RTP header extension mechanism.

-- 
Colin Perkins
http://csperkins.org/

---

From: Alan Clark <[email-masked]>
Date: Fri, 19 Jun 2009 12:08:51 -0400

A parallel problem is the control (rather than indication) of volume and
noise suppression in VoIP calls.  911 operators find that sometimes they do
want noise suppression and sometimes they don't.  Noise suppression can be
helpful when they are trying to understand a caller in a noisy background
environment however it can also suppress background noises that can help to
understand the emergency situation (e.g. if they hearing kids laughing in
the background the call may be a prank (which does happen quite frequently)
but other sounds may indicate how serious a problem is or provide location
information).

Alan

---

From: David R Oran <[email-masked]>
Date: Thu, 25 Jun 2009 16:04:35 -0400

> but other sounds may indicate how serious a problem is or provide  
I would think the right mechanism for this would be CCM (Codec Control  
messages), not header extensions.

> _______________________________________________
> Audio/Video Transport Working Group
> [email-masked]
> https://www.ietf.org/mailman/listinfo/avt

---

From: Randell Jesup <[email-masked]>
Date: Thu, 25 Jun 2009 16:18:53 -0400

David R Oran <[email-masked]> writes:
>> A parallel problem is the control (rather than indication) of volume
>> and noise suppression in VoIP calls.  911 operators find that
>> sometimes they do want noise suppression and sometimes they don't.
>> Noise suppression can be helpful when they are trying to understand a
>> caller in a noisy background environment however it can also suppress
>> background noises that can help to understand the emergency situation
>> (e.g. if they hearing kids laughing in the background the call may be
>> a prank (which does happen quite frequently) but other sounds may
>> indicate how serious a problem is or provide location information).
>>

CCM seems more correct; header extensions aren't really designed/meant
for a control backchannel -- CCM is.  

The downside is that CCM requires AVPF, which because of how
capabilities work in SDP is a real pain.  Header extensions are easier
to just send and if the other side doesn't understand them, oh well.
Putting AVPF in a negotiation will 'break' attempts to talk to most SIP
equipment in the field.  (Some simply ignore the profile...)  Cap-neg
may make it possible to negotiate the profile, but again most things
don't support that, and needing it in order to use AVPF/CCM adds a
significant amount of additional complexity (plus I don't know if
cap-neg is near finalization).

So, it's a pain.  CCM is "right", but would require either major
compatibility pain OR would require implementing cap-neg, which is a
major pain.

-- 
Randell Jesup, Worldgate (developers of the Ojo videophone), ex-Amiga OS team
[email-masked]
"The fetters imposed on liberty at home have ever been forged out of the weapons
provided for defence against real, pretended, or imaginary dangers from abroad."
		- James Madison, 4th US president (1751-1836)