Hello all,
A new release of jack_delay is available at
<http://kokkinizita.linuxaudio.org/linuxaudio/downloads>
> From the README:
jack_delay 0.4.0 - 18/04/2011
-------------------------------
Jack_delay can be used to measure the round-trip latency of a soundcard.
To do this, start the program and connect like this:
jack_delay -> playback_port -> cable from soundcard output to input -> capture port -> jack_delay
Jack_delay generates a signal consisting of 13 sine waves, measures the
phase difference between the input and output for each of these, and
computes the delay from those phase differences. The algorithm used is
one developed originally for satellite ranging - that is measuring the
distance between a satellite and a ground station.
With a good sound card jack_delay will measure the round-trip latency
with an accuracy of around 1/1000 of a sample. The assumption is that
the delay is more or less independent of frequency. The actual value
displayed is the one for a frequency of 1/16 of the sample rate. The
phase measurement for this frequency of course only provides a result
in the range of 0..16 samples. The other frequencies are used to extend
this interval to 4096 * 16 samples, more than a second at 48 kHz.
This release should be much less sensitive to frequency-dependent delay
than the previous ones.
The following options are avaiable (use jack_delay -h to see them):
-O playback port connect output to named port.
-I capture port connect input to named port.
-E show excess latency instead of full latency.
Using -E requires -O and -I, as the the computation depends on
the latency values reported by jack for the ports used.
The excess latency is the measured value minus the expected one,
taking into account any corrections set by jack's -I and -O options.
That is, if you have the right values for these options, then the
value displayed with -E will be at most +/- half a sample.
To determine the correct values for jack's -I and -O, set both
of them to zero ('default' in qjackctl) and measure the latency
using the -E option. Then set each of the -I and -O options to
half the value displayed.
Ciao,
--
FA
On Mon, Apr 18, 2011 at 4:52 PM, S. Massy <lists(a)wolfdream.ca> wrote:
> Thanks,
> Builds and runs fine on Debian Wheezy AMD64. What latency would be
> considered average? What numbers should one expect?
the "excess" value is generally on the order of several tens of
samples in each direction. it can reach as high as the low hundreds.
with USB audio (and potentially some firewire devices, the excess can
even get up into the thousands, but its dependent on a variety of
factors. this assumes you are doing the obvious thing and measuring a
loopback via a D/A and A/D converter pair.
for reference, my RME HDSP system, connected to a Frontier Designs
Tango24 converter, meaures 68 samples of total excess latency, so
about 34 in each direction.
One thing I forgot to mention: this release of jack_delay
requires a Jack version providing the new latency API.
AFAIK that is Jack >= 0.120.1
Ciao,
--
FA
Hi everybody.
This is the second release of aj-snapshot, which is a command line
utility to store/restore ALSA and/or JACK connections.
For more information: goto http://aj-snapshot.sourceforge.net/
Changes in this release:
- Ask for confirmation when the user saves a snapshot over an existing file.
and added the '-f/--force' option to override this.
- Added the '-q/--quiet' option. With this option aj-snapshot will not report
any information about storing/restoring connections. This includes messages
about connections that aj-snapshot failed to restore, because they are not
considered an error in this context.
- Added an '-i/--ignore' option with which you can tell aj-snapshot to ignore
certain clients when storing/restoring connections.
- Made the connection messages more readable.
To clone the git repository:
git clone git://aj-snapshot.git.sourceforge.net/gitroot/aj-snapshot/aj-snapshot
Let me know if you have any questions...
I hope you enjoy :-)
lievenmoors
Hi all,
It's been online for a while, but with 4 weeks to go: the
conference-programme is now officially fixed:
http://lac.linuxaudio.org/2011/?page=program
and for your xPhone or googol-calendar:
http://lac.linuxaudio.org/2011/vcal.php
Should you attend LAC, please register if you have not done so:
http://lac.linuxaudio.org/2011/?page=registration
If you can not make it to Maynooth: live streams will be available
during the conference and the recordings and papers will also be
published online afterward.
Looking forward to seeing you in Maynooth!
PS. We are going to provide some printed copies of the programme at
the conference registration-desk, but if you wish to do a colorful print
yourself:
http://lac.linuxaudio.org/2011/printprogram.php
Set your browser's File->Print->Options->Print background colors
or simply run:
wkhtmltopdf -s A4 --minimum-font-size 18 \
http://lac.linuxaudio.org/2011/printprogram.php \
lac2011.pdf
--
Robin Gareus
84bis Rue de Grenelle
75007 Paris, France
mobile: +33 612 738 346
mailto: robin(a)gareus.org
jabber: xmpp:rgareus@ik.nu
phone & fax: +33 95 222 567 2
Public Key at http://pgp.mit.edu/
Fingerprint : 7107 840B 4DC9 C948 076D 6359 7955 24F1 4F95 2B42
Hi,
What is needed for a working jack session environment?
I was hoping to be able to use it with qjackctl-0.3.7 and jack-0.120.1
but this fails to work:
1) When "Save and Quit" is selected and "Save.." has finished, nothing quits.
2) Applications rarely start when a session is loaded and the entries
in the session window have red crosses next to them.
I need a working jack session environment because I'm trying to code
and test Petri-Foo's Jack session support.
So far the set session callback returns without error, but the
callback is never called (when using the setup mentioned above).
I briefly tried pyjacksm but get "inconsistent use of tabs and spaces
in indentation" errors (is that because of python3/python2 conflicts
arising from scripts starting with #!/usr/bin/python ? I tried adding
a sed to the AUR PKGBUILD but failed to find the correct
search/replace terms.)
Any help appreciated,
Cheers,
James.
I did not get any? ... Not from LAD and not from Gene. Something is
working though since Veronica apparently could see the message from
Gene.
Trying once more
/j
On Tue, 2011-04-12 at 23:08 -0700, Veronica Merryfield wrote:
> On 2011-04-12, at 2:04 PM, gene heskett wrote:
>
> > On Tuesday, April 12, 2011 05:03:51 PM Jens M Andreasen did opine:
> >
> >> Test: ISP ate my e-mail ...
> >>
> >> /j
> >>
> > And this one made it through the gauntlet.
> >
> Or the ISP was sleeping off it's meal.
>
>
>
Nope. And not this one either. Only from you Veronica.
/j
On Wed, 2011-04-13 at 00:56 -0700, Veronica Merryfield wrote:
> Did you get your original test returned to you?
>
> On 2011-04-13, at 12:49 AM, Jens M Andreasen wrote:
>
> > I did not get any? ... Not from LAD and not from Gene. Something is
> > working though since Veronica apparently could see the message from
> > Gene.
> >
> > Trying once more
> >
> > /j
> >
> > On Tue, 2011-04-12 at 23:08 -0700, Veronica Merryfield wrote:
> >> On 2011-04-12, at 2:04 PM, gene heskett wrote:
> >>
> >>> On Tuesday, April 12, 2011 05:03:51 PM Jens M Andreasen did opine:
> >>>
> >>>> Test: ISP ate my e-mail ...
> >>>>
> >>>> /j
> >>>>
> >>> And this one made it through the gauntlet.
> >>>
> >> Or the ISP was sleeping off it's meal.
> >>
> >>
> >>
> >
> >
>
