[Jack-Devel] Latency issue solved

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DateSun, 01 Apr 2012 13:50:24 +1000
From Ben Briedis <[hidden] at hotmail dot com>
To[hidden] at lists dot jackaudio dot org
Hi everyone,

I'd been having a problem with latency recently which I've just solved 
(cross fingers).  The latency I was measuring through jack_iodelay was 
somewhat unpredictable.  It could change after rebooting the machine, 
after saving settings to the firmware of my audio interface
and occasionally after xruns.  This made latency correction difficult.

I solved the problem by flashing the BIOS.  I hadn't done it sooner as I didn't 
have a Windows partition and it was impossible to flash it from Linux.

Now the latencies seem very stable.  If I loop the signal out of the audio interface
and back in again and record the input on Ardour then I see no variation at all.
Any variation in latency seems to be less than one sample!

I though it was important to send this email as I haven't see anyone write that
this sort of performance can be expected.  Also I haven't seen anyone
mention recently that flashing the bios might be cure to latency ills.

For the record my audio interface is an Audio Fire 4 (firewire), my computer 
is a Toshiba Satellite A100 (a dual core), I'm running a custom rt kernel,
and using the Arch Linux distro.

Cheers,
Ben

	   		 	   		  
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