Re: [codec] #8: Sample rates? 44.1kHz?

One more, added in line---

On Fri, Apr 16, 2010 at 6:52 AM, stephen botzko <stephen.botzko@gmail.com>wrote:

> -Support of 48 kHz in sound cards, etc. is quite widespread, so personally
> I see no requirement for 44.1 kHz (or 22.05, 11.025).
>
> -RTP timestamp granularity of 96 kHz would be pretty hard to get through,
> unless we actually have a 96 kHz mode of operation.  I don't see any
> requirement for such a mode (though CELT happens to do it)
>
> Might be worth summarizing where we are at this point:
>
> -There appears to be a consensus that the RTP time base needs to remain
> constant despite any changes to acoustic bandwidth. (due to network
> adaptation)
>
> - There is a consensus that frequent changes to acoustic bandwidth results
> in a disturbing / unpleasant listening experience.
>
> - There is consensus that it is ok to reduce the acoustic bandwidths at
> lower bitrates,
>

             *  - There is consensus that 48 kHz (fullband) operation is a
requirement.*

>
> - There is no consensus (as of yet) as to how many or which sampling rates
> we need for the "internal codec", including no consensus that we need more
> than one.  It is important to note that no one has *objected* to multiple
> sample rates either. Though it has been observed that multiple sample rates
> makes compressed domain mixing problematic.
>
>
> Stephen Botzko
>
>
>
> On Fri, Apr 16, 2010 at 12:44 AM, Christian Hoene <hoene@uni-tuebingen.de>wrote:
>
>> Hi all,
>>
>> >It might be useful to state that it is not recommended to use 44100 Hz,
>> because the conversion to
>> >16kHz and 32kHz is computational more demanding than 48kHz and requires
>> more power/time.
>>
>> Currently, proposed codec run at sampling rates of
>>
>> BroadVoice: 8, 16 kHz
>> SILK: 8, 12, 16, 24 kHz
>> CELT: 32 kHz to 96 kHz.
>>
>> I do have a question. In order to make the RTP handling and the resampling
>> simpler, it might be useful to skip the 44.1kHz compression mode. If only 8,
>> 12, 16, 24, 32, and 48 kHz sampling rates are used, then the RTP timestamp
>> can be easily counted in 96 kHz units. Supporting 44.1 kHz would require
>> fractions of time stamp units that are difficult to handle with. Also, the
>> resampling take more computational resource if it has to be done at high
>> quality.
>>
>> Thus, my question: Is 44.1 kHz really much-needed or can we use 32 or 48
>> kHz instead?
>>
>> Christian
>>
>>
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>>
>
>