[Ardour-Dev] zita-a2j and capture alignment

Fons Adriaensen fons at linuxaudio.org
Tue Sep 10 06:05:20 PDT 2013

On Tue, Sep 10, 2013 at 08:32:51AM -0400, Paul Davis wrote:

> Ardour cannot correct the case where the source (the JACK backend or zita)
> are not in agreement. Sorry, this is asking for the absurd. The regions are
> not a different length - they contain different data. Pop up the region
> properties editor (right click on a region > properties) to establish this.
> Their data is different because there is a skew between the two sources.
> Nothing ardour can do (or know) will improve this.

So how (if at all) does ardour use the capture latency values when recording ?

Suppose you have two identical sound cards. One is used by Jack's backend,
the other by zita-a2j. Both set the correct capture latency value on their
ports. For a2j this will of course be a higher value than for the backend.

Connect the same signal to the two cards, record two tracks simultaneously,
one from each card. 

I'd expect the two resulting regions

* to be in sync when played back,
* to have different start/end points.

assuming ardour uses the capture latency values to offset the regions.

If not, how are the latency values used ?



A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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