RE: [AVT] VoIP Shim for RTP Payload Formats

["Desineni, Harikishan" <hdesinen at qualcomm.com>]

I am under the impression that in-band signaling inside payload header
is an accepted concept in this community. Other than AMR Payload format,
there is another payload format which is trying to use this concept.
Once such work is the use of MBS field in Sec 5.2
draft-ietf-avt-rtp-g729-scal-wb-ext-07.txt

"MBS (4 bits): maximum bit rate supported.  Indicates a maximum bit
 rate to the encoder at the site of the receiver of this payload."

I think that RTCP (AVPF) has a similar message which can be used to
convey maximum bit rate to the encoder at the remote end.

I'd like to infer the following statements from the reference to the
above work in RTP and RTCP:

1) In-band signaling using RTP payload header is an allowed/accepted
concept.
2) RTCP signaling may also exist to carry the same information.

In certain scenarios (MOH, voice mail), RTCP signaling is unavoidable.
One will end up defining methods to carry the same information using
both in-band RTP and RTCP based feedback.

-----Original Message-----
From: Colin Perkins [mailto:csp at csperkins.org] 
Sent: Friday, August 25, 2006 7:30 AM
To: Ingemar Johansson S ((LU/EAB))
Cc: avt at ietf.org
Subject: Re: [AVT] VoIP Shim for RTP Payload Formats

> Inband signaling of the type proposed already exist for eg.
> the AMR payload format (RFC3267), it is however limited to the
> request of lower/higher codec rate. The intention of this added
> inband signaling is to allow for requests regarding frame aggregation
> and redundancy during a session so in that aspect it is a
> continuation of the inband signaling concept that already exist.

This is one of the less desirable features of the AMR payload format,  
and was included solely for backwards compatibility.


Colin

_______________________________________________
Audio/Video Transport Working Group
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_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www1.ietf.org/mailman/listinfo/avt