[LAU] FOSS Ethernet Soundcard

[fons at kokkinizita.net]

On Tue, Nov 24, 2009 at 10:15:05AM +0100, Florian Faber wrote:

> >> So I will plug this into my ethernet and have < 1ms latency? :)
> > Given the fact that AD/DA converters introduce more then one ms latency(*) 
> > already: No.
> 
> That depends on the converter and the sample frequency. Fast converters
> can go as low as 5 samples conversion latency.

It's not the AD/DA conversion that introduces most of the delay.
At 44.1 or 48 kHz the antialiasing filters are the main cause
of delay. A linear phase filter with a transition band of 1khz
(e.g. unity gain up to 21 kHz and near zero at 22 kHz) must
have a delay of around 1/1kHz or 1 ms. 

Short delays are possible at 96 kHz, where you can have full gain
up to say 28 kHz going down to zero at 48 kHz. That's a range of
20 kHz, corresponding to 0.05 ms. It's one of the few advantages
of higher sample rates (but only if you don't use the full band-
width).

Ciao,

-- 
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.