[Ardour-Dev] zita-a2j and capture alignment

[Ben Bell]

On Sat, Sep 07, 2013 at 03:27:21PM +0100, Ben Bell wrote:
> 2) When I capture a mix of jack driven and zita-a2j driven inputs, the
>    alighment is out. I don't just mean audio latency, I mean that the
>    captured regions have different start times. I'm guessing something is
>    trying to be smart about re-aligning the two sources but it's not
>    getting it right. In addition, by moving the region starts it seems
>    to break the edit-group synching of region edits.

Having been through this in more detail with Fons's help and a new version
of zita-a2j, it looks like there is definitely something going in on Ardour
itself here. 
The regions being captured from the Zita and Jack driver cards are of
slightly (e.g. 12 samples) different lengths, and this seems to mean that
the code in ardour which handles ganging of edits for regions in an edit
group is being fooled. Assuming that the different length regions are a
valid response to what's happening, does Ardour need to use a different
method of deciding whether a pair of regions are part of the same take and
hence should be edited together -- maybe just start time? Or should the
regions be artificially made the same length if they are recorded together
in an edit group?

bjb