[LAD] JACK Graph Internal Latency? (was Re: A small article ...)

Rui Nuno Capela rncbc at rncbc.org
Thu Apr 29 10:41:41 UTC 2010

On Thu, 29 Apr 2010 13:44:02 +0400, Louigi Verona
<louigi.verona at gmail.com>
> Well, from what Paul said it appears it is not Qtractor, it is the same
> with
> Ardour and basically just any loop connections setup.
> Or am I getting it incorrectly? Let's wait for what Paul has to say %)
> On Thu, Apr 29, 2010 at 1:32 PM, Ralf Mardorf
> <ralf.mardorf at alice-dsl.net>wrote:
>> Louigi Verona wrote:
>>> My version is 0.44, I think. pretty late one, I compiled ot from git
>>> February or January.
>>> I can try another version or another app for that matter. But let Paul
>>> tell us if it makes sense at all.
>> I guess Rui programmed buggy for Qtractor, it wasn't a fault for JACK1
>> JACK2. Perhaps 4.4.5+ is needed.

the zero-copy issue was indeed a sloppy bug in older qtractor versions.

the issue at hand (OP) is that there bouncing, recording or feeding back
outputs to own inputs, which is quite equivalent to returns from sends on
inserts, adds at least one buffer or period cycle latency to the
bounced/return signal


    qtractor-out  -> rackarrak -> qtractor-in

as insert to track or bus:

    qtractor-send -> rackarrak -> qtractor-return

you can swap qtractor for ardour, or anything else for that matter and the
latency will be exactly the same systematic. a client can only process the
results of its own outputs or sends in the _next_ process cycle. 

rncbc aka Rui Nuno Capela
rncbc at rncbc.org

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