[ardour-users] Exporting with Hardware Inserts/Sends

[Paul Davis]

On Sun, 2006-01-22 at 11:52 +1030, Andrew Johnston wrote:
> It seems that the ability to export a session that contains hardware
> inserts or sends is not available yet.  Would I be correct in saying
> this?  I have managed to connect inserts through to my mixer and
> applied various effects and what not (of course there is a small amout
> of latency), but when i export the tracks with the inserts are silent.
> I guessed this was the case as the export is not in real time which
> would tend to make it impossible for hardware inserts to work, just
> thought there might be an option one can change.  

no, its not possible because we do export by setting jack into
freewheeling mode. in this mode, jack no longer is timed by the audio
interface, it just runs "as fast as possible" (which is probably faster
than realtime, but might not be). consequently, any external devices
will lose sync with what is going on, totally messing up the result.

however, you should not have been able to even do an export under these
conditions - ardour tries to check for this and tells you that its a
problem.

the correct technique is to just bounce down to a different track:
create a new track, make its inputs be connected to whatever you want to
export (e.g. master outs) and make sure its outputs do *not* feed into
that signal. then just do a normal recording pass and you should get
the external h/w as part of the export just fine.

> While I'm on the subject, how on earth to pro-tools mix and hd systems
> achieve zero latency on the hardware inserts?  I have used the system
> before, and I can understand zero latency monitoring as the signal
> passes through a patchbay to the hardware on the way to the speakers,
> but with inserts it goes out and comes back...hmmm

protools uses a DSP farm that does single-frame processing, not block
level processing like (almost) any general purpose CPU does. so their
h/w reads 1 sample at a time, and feeds it through the signal processing
pathway. they can't get *zero* latency (thats impossible) but they can
get very low latency.

> Avid Ardour User (no pun intended)

if we have any users inside avid, i'd love to hear about it :)