[LAD] Looping audio to oneself via Jack

Ralf Mardorf ralf.mardorf at alice-dsl.net
Mon May 23 04:12:00 UTC 2011

On Mon, 2011-05-23 at 00:17 +0000, Fons Adriaensen wrote:
> On Mon, May 23, 2011 at 12:48:05AM +0200, torbenh wrote:
> > > Note that fixing this does not imply you can't get your own
> > > undelayed output anymore. That just depends on the order of
> > > your computations and jack_port_get_buffer() calls.
> > 
> > but we would eliminate a lot of zero-copy codepaths inside
> > a client like ardour.
> > (note that ardour has quite a lot of ports connected to itself)
> And these would typically be busses, and have more than
> one output port connected to them. Nothing to be optimised
> in that case.

Yes, but for my last production I e.g. had two syn bass sound audio
tracks routed to a bus. When doing the mastering, I decided to remove
one bass, but I kept the bus for the left bass, because of the plugins.
I also added a bus for the drums, now there're several audio tracks
routed to this bus, but at the beginning only one audio track was routed
to it.

At least the second scenario is a typically situation, where just one
source is connected to a bus.

That might explain some voodoo. A long time ago I had a loss for the
sound quality when using Qtractor, IIRC it was caused by a zero-copy
issue and everything was ok after avoiding the bad connection.
Some days ago I had the same kind of loss when recoding a soft synth
internal Linux (no sound card involved) by Ardour. Perhaps it wasn't
voodoo ;)?

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