[LAU] I really need help with jack

david gnome at hawaii.rr.com
Mon Jan 28 07:52:34 UTC 2013

On 01/27/2013 07:26 AM, Bob van der Poel wrote:
> 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
> audio_reservation_init
> 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?

I have QJackCtl 0.3.9.

>> 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.

I just prefer to use the highest quality sample rate it supports. 
Removes one resampling step from the audio processing chain. But, really 
- how much music is distributed on CD these days, vs electronic download?

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


gnome at hawaii.rr.com
authenticity, honesty, community

More information about the Linux-audio-user mailing list