[Ardour-Users] jack2 sync/async mode -- was: ardour 3.0 alpha season drawing to an end

Robin Gareus robin at gareus.org
Sun Jul 17 08:43:34 PDT 2011

On 07/17/2011 01:08 AM, Casey Shultz wrote:
> Thanks for the info Robin. I'm a bit unclear on how to start jackd2 and
> Ardour 3 in synchronous mode. The "-S" doesn't show in the jackd
> documentation that I have.

Hi Casey,

Async/Sync mode is specific to the jackdmp aka jack2 implementation.
I guess the man-page for jackd is the same for jack1, jack2 and tschack
on your distribution so implementation specific options are not be
documented there.

# jackd --help
    [ --sync OR -S ]

You can launch jack from the command-line _before_ starting ardour:

   jackd -S -d alsa -dhw:0 -r48000 -p1024 -n2


you can launch it with qjackctl. In Setup->Settings change the "Server
Path" from "jackd" to "jackd -S" (without the quotes).

Neither qjackctl, nor the ardour-built-in-start-engine-dialog have
dedicated support for that option. But at least with qjackctl you can
work-around this with the hack mentioned above.


PS. There are a few other ways to launch and control jackd. e.g. the
DBUS interface or JackPilot on OSX, ... If you're interested in those,
get back to me or ask on the jack-devel email-list: Stephane (author of
jackdmp) is very kind and usually responds quickly.

PPS. This has nothing to do with ardour. Except for the issue that some
implementation specific detail (Jack2 printing "JackActivationCount"
error messages in async mode) may /screw up/ ardour. However this
behaviour has recently been fixed in jack2.

It boils down to: http://trac.jackaudio.org/wiki/Q_differenc_jack1_jack2

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