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

[Colin Perkins <csp at csperkins.org>]

Qiaobing,

On 24 Sep 2004, at 13:16, Qiaobing Xie wrote:
> Colin Perkins wrote:
>
> <snip>
> > > Not that such things exist currently, but playing devil's advocate,
> > > one could create a codec that takes a variable-sampling-rate input
> > > depending on current conditions.  (Similar to video codecs that vary 
> > > the
> > > frame rate, resolution, and/or bitrate within a stream.)
> > Sure, one could. I don't think it would be a good idea though: the 
> > convention that the sampling rate equals the timestamp rate is very 
> > helpful when building multi-format systems.
>
> The practical need in 3GPP2 (and possibly other systems) to feed mixed 
> sampling rate input (depending on conditions in the call flow) to 
> vmr-wb codec in a single session has already been explained in this 
> discussion. I think it is quite equivalent to the scenario depicted by 
> Randell.

With respect, the only argument I've heard is that you want to save 
having to store both 8kHz and 16kHz sampled clips in a system. That is 
not a compelling reason to break the RTP timing model.

Colin


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