1 Jan
2014
1 Jan
'14
3:10 p.m.
Hello list,
I've come across a problem where the hardware latency numbers entered into
qjackctl setup window don't take effect. I wrote up the details here:
http://quinoa.blizinski.pl/~maciej/latency/calibration-problems.html
The workaround was to start jackd from command line and pass the -I and -O
options that way.
It is possible (but not certain) that the problem was caused by qjackctl. I
wrote a post on the qjackctl forum, but I'm not sure how much attention it
gets.
http://www.rncbc.org/drupal/node/749
Since my setup is fairly common components: Ubuntu 13.10 with ardour, jackd
and qjackctl installed from packages, it sounds like I shouldn't be the
only person to experience this problem.
Has anyone else come across that?
Maciej
1 Jan
1 Jan
4:33 p.m.
On 01/01/2014 03:10 PM, Maciej (Matchek) Bliziński wrote:
Hello list,
I've come across a problem where the hardware latency numbers entered into
qjackctl setup window don't take effect. I wrote up the details here:
http://quinoa.blizinski.pl/~maciej/latency/calibration-problems.html
nice writeup.
Once the 'problem' is understood and fixed, it'd be great to make a "how
to calibrate latency" walk-trough out of it. You already have nice
"before and after" screenshots.
The workaround was to start jackd from command line
and pass the -I and -O
options that way.
If it's jackdbus that you're using, maybe qjackctl does not configure it
properly; or maybe you're just missing 'use dbus' in qjackctl's config?!
-- but those are only guesses. One could look in the source or bug Rui :)
A few things that may help to track things down:
'jack_control dp | grep latency'
prints the current configuration of jackdbus.
You can directly query the current port-latencies with 'jack_lsp -l'. It
lists the actual port-latencies as jack knows them, that includes
cycle-times, -I/-O configuration and latencies due to routing: eg.
effects with latencies, etc.
It is possible (but not certain) that the problem was
caused by qjackctl. I
wrote a post on the qjackctl forum, but I'm not sure how much attention it
gets.
http://www.rncbc.org/drupal/node/749
Since my setup is fairly common components: Ubuntu 13.10 with ardour, jackd
and qjackctl installed from packages, it sounds like I shouldn't be the
only person to experience this problem.
Has anyone else come across that?
Maciej
9:29 p.m.
On Wed, 1 Jan 2014, Maciej (Matchek) Bliziński wrote:
Hello list,
I've come across a problem where the hardware latency numbers entered into
qjackctl setup window don't take effect. I wrote up the details here:
The workaround was to start jackd from command line and pass the -I and -O
options that way.
As qjackctl comes from Ubuntu, it tries to control jackdbus and not jackd.
This can be changed in qjackctl settings, but probably will not help :)
The real problem is probably (use ps x to check) that jackd is already
running before you start qjackctl which means qjackctl can not control
jackd. Why might this happen? Normally it is because you have started an
application that requires jack and that process has started jack for you
with whatever it thought was good parameters. The cure is to always start
qjackctl and use it to start jackdbus before running anything that uses
jack as soon as you login.
To test this, logout, login, start qjackctl, use it to start jack. You can
use qjackctl's "Status" window to see what parameters are current.
--
Len Ovens
www.ovenwerks.net
3775
days inactive
3775
days old
linux-audio-user@lists.linuxaudio.org
2 comments
3 participants
participants (3)
-
Len Ovens -
Maciej (Matchek) Bliziński -
Robin Gareus