[LAU] Audio interface latency measurements

[Len Ovens]

On Sat, 21 Jun 2014, Jeremy Jongepier wrote:

> On 06/21/2014 07:18 PM, Len Ovens wrote:
>> I am not sure, but it seems to me the USB1.1 audio standard effectively
>> means that the lowest latency for USB1 is jackd set to 64/2.
>
> With my Edirol UA-25 lowest possible setting is 48/2 @ 48kHz.

I hadn't tried that... or to be honest 32/3. I have been lazy not thinking 
outside the 16/32/64/128 box  :)

> This is the
>> smallest buffer size supported. I do not know, but it seems that fire
>> wire audio is about the same from what I have read (I don't have one of
>> my own to confirm).
>
> With the FireWire interfaces I've owned I could go as low as 16/3 @
> 48kHz. But settings like this are unusable, DSP load qickly rises as
> soon as you start doing something serious. Nice to brag about but that's
> about it ;)

Is that the DSP load in the audio interface itself or the computer? I have 
found that  16/2 at 48k for use with guitarix (in other words as an 
effects rack) is very solid. (ice1712 pci interface) I am using a 
lowlatency kernel, but not RT. No hyperthreading (got the i5 for that 
reason) no CPU frequency changes. Not a super great tunning, but all the 
low hanging fruit for sure. Any modern computer should be able to deal 
with the load for at least some uses. Though I guess my atom should be 
considered "modern"... it does really well down to 64/2, I will have to 
try pushing a bit further, but I don't think it will go much lower and 
still have cpu cycles to run the SW.



--
Len Ovens
www.ovenwerks.net