[LAD] JACK latency compensation on USB audio devices

Joakim Hernberg jhernberg at alchemy.lu
Thu Sep 3 21:42:20 UTC 2015


On Wed, 2 Sep 2015 23:51:36 +0200
Adrian Knoth <adi at drcomp.erfurt.thur.de> wrote:

> On 09/02/15 21:35, Joakim Hernberg wrote:
> 
> > Well yes, I'm aware of that and it was this extra latency that I
> > wanted to ascertain. What puzzles me is that each time the jack
> > server is invoked, it will need a different amount of latency
> > compensation even when no other parameters have changed.
> 
> Didn't Fons mention a similar problem lately? (think two weeks ago).
> 
> He's currently travelling, but maybe you want to check out his patches
> (yet to be posted).
> 
> Note that Fons' patches are only about client execution order in
> jackd1. If you also get different values in jackd2, then it's either
> unrelated or needs fixing as well.

IIRC the problem Fons uncovered had to do with the effective latency
changing by one period when clients connected/disconnected.  This
doesn't appear to be related.  And AFAIK it only happens with USB
devices.

-- 

   Joakim


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