[LAU] I really need help with jack

Bob van der Poel bob at mellowood.ca
Sun Jan 27 17:26:34 UTC 2013

Hey, I have some success to report !!!!

> I record regularly (and play back) using JACKD, Audacity and a UCA202. I'm
> using Debian Sid WITHOUT PULSEAUDIO or an RT kernel.
> I use QJackCTL to start JACK with these settings:
> Server prefix: "/usr/bin/jackd -S --realtime
> Realtime box: checked
> Priority: DEFAULT
> Frames/period: 1024
> Sample Rate: 48000
> Periods/buffer: 3
> Dither: None
> Audio: Duplex
> Input device: hw:1
> Output device: hw:1
> Channels I/O: 2 (for both)
> Latency I/O: Default (for both)

Okay, this is a start. I tried it and it sort of works. Problem is
that on playback I get motorboat sound. Not what we want. I also get a
bunch of dbus errors while jack is trying to start.

So, decided to give it one last try :)

I have pulse running, etc. From a command line:

pasuspender -- jackd -d alsa -d hw:1

jackdmp 1.9.8
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2011 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
Cannot lock down 82241434 byte memory area (Cannot allocate memory)
control device hw:1
control device hw:1
Acquire audio card Audio1
creating alsa driver ... hw:1|hw:1|1024|2|48000|0|0|nomon|swmeter|-|32bit
control device hw:1
configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 16bit little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 16bit little-endian
ALSA: use 2 periods for playback

Start up audacity ... and it works! Using audacity setting Overdub On
I get the background playing out of the usb headphone jack. And
recording seems to be fine. Just spoke some <this is a test> stuff
into the mic, but that seems to work. I'll try my sax later.

I have no idea why the qjackctl is barfing. Versions?

> Settings in Audacity:
> Set your project rate to 48000Hz.

Does this make a difference? I have jack running now at 48000 and
audacity at 44100 and it sounds fine.

So, some progress on a cold winter's day. Wonderful.

**** Listen to my CD at http://www.mellowood.ca/music/cedars ****
Bob van der Poel ** Wynndel, British Columbia, CANADA **
EMAIL: bob at mellowood.ca
WWW:   http://www.mellowood.ca

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