Re: [Jack-Devel] Testing jack_iodelay

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DateTue, 23 Aug 2011 07:25:24 -0400
From Paul Davis <[hidden] at linuxaudiosystems dot com>
ToStéphane Letz <[hidden] at grame dot fr>
CcJACK Developers <[hidden] at jackaudio dot org>
In-Reply-ToStéphane Letz Re: [Jack-Devel] Testing jack_iodelay 
On Tue, Aug 23, 2011 at 6:05 AM, Stéphane Letz <[hidden]> wrote:
> Le 23 août 2011 à 09:40, Stéphane Letz a écrit :
>
>> Hi All,
>>
>> I'm currently testing jack_iodelay with jack2 SVN on OSX and get this kind of result:
>>
>> Signal below threshold...
>>   926.942 frames     21.019 ms total roundtrip latency
>>       extra loopback latency: 21 frames
>>       use 10 for the backend arguments -I and -O
>>
>> Since OSX CoreAudio drivers report their internal latencies (as the "input latency offset", "input latency", "output latency", "output latency offset"), and since those values are reported in JACK notion of in/out latency, the result should be better.
>>
>> What is the expected precision of jack_iodelay?
>>
>> Stephane
>
> I actually get different values for this "extra loopback latency" when running jack_iodelay several times with same JACK server setup. So something is wrong. What should I look for?

the expected precision is sub-sample.

i'd recommend that you (a) check the port latencies (e.g. with
jack_lsp -l) (b) check the jack2 iodelay code against the jack1
version (c) double-check your physical wiring.
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