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Re: [AVT] RE: <draft-ietf-avt-rtp-vmr-wb-03.txt>: sampling rate

Colin Perkins <csp@csperkins.org> Sat, 11 September 2004 11:18 UTC

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From: Colin Perkins <csp@csperkins.org>
Subject: Re: [AVT] RE: <draft-ietf-avt-rtp-vmr-wb-03.txt>: sampling rate
Date: Sat, 11 Sep 2004 12:06:24 +0100
To: Magnus Westerlund <magnus.westerlund@ericsson.com>
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Magnus,

On 8 Sep 2004, at 12:36, Magnus Westerlund wrote:
> Based on what you write in the previous mail. It seems that the only 
> reason for using different RTP timestamp rate between 8000 and 16000 
> Hz is to indicate the sampling rate of the source material. If the 
> codec does not need any indication at all if the source material is 8k 
> or 16k then, I think the usage of different RTP timestamp rates is 
> creating unnecessary interoperability barriers. The barrier is that 
> one actually needs to indicate the rate of the source material, and 
> cope with RTP timestamp switching.
>
> To avoid the unnecessary function I would propose that VMR-WB only 
> defines 16kHz as RTP timestamp rate.

I disagree.

> If there is desire to have knowledge about source sampling rate that 
> will be used, then one should define a parameter that indicates that.

All RTP audio payload formats need that knowledge, since it determines 
the RTP timestamp rate. This is the purpose of the "rate" parameter.

Colin


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