Click/Crackle/Chopiness on audio output (JACK problem?)

Installation & Configuration Linux
#1

Hi. I am really new to all this, and barely even know what I am clicking (no pun intended) on in the application. Anyway, it looks very impressive, and I am so far able to connect my guitar multi-fx unit’s USB Audio output into the computer, and using software-monitoring I can hear the output.

However I have a problem. The audio output (through my onboard sound) is very crackly/choppy and broken. I expect this may be a kernel/JACK problem but I wonder if anybody has any advice.

I got out of bed early this morning with a brainwave - try 44,1KHz instead of 48k or vice-versa, but alas it makes no difference.

I can hear the crackling just listing to the inbuilt “click” metronome.

My machine is an Intel Core 2 Quad Q6600. I have no realtime kernel enabled. I could try moving to one, but I seem to remember reading that nVidia’s proprietary graphics module doesn’t work with RT kernel… (I had all those problems trying to use the nVidia module with a Xen kernel and believe the problem also relates to RT kernel).

My output device is : 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 02)
I think the actual hardware codec thing is an Analog Devices. ALSA says it’s ALC882.

I am using qjackctl before starting Ardour. Previous to this I was not, and I beleive Ardour was starting up jackd by itself. I couldn’t see where to alter sample rate and other jackd settings within Ardour so I started qjackctl before running Ardour and Ardour happily goes along with that instance, showing the sample rate that I set in the corner.

Others I have read have all found it to be sample rate related, but this isn’t helping :frowning:

I am using Fedora 8 on x86-64.

Hope you can help - thanks!

#2

Not having a realtime kernel is most likely your problem. Nvidia works fine with a realtime kernel on my system and on every other distro i’ve ever used. If you don’t want to get a realtime kernel you will need to have your frames/periods set to minimum of 1024, and you will need to read up about setting your system to give audio threads preference over other processes…google for jack and /etc/security/limits.conf.

Good luck

#3

Thanks Solv. I have just come back to say that I have had some good sucess:

I changed “Periods/Buffer” to 4 (from 2) and it has stopped the clicking. It now sounds fine except for a some small latency that I can live with for now.

I will play with the frames/period as well, although it is on 512 at the moment and sounding good!

Super.

#4

great stuff

#5

Thanks to this thread for some more ideas.

I’m running Ubuntu Studio (RT-Kernel already built), and while I’m waiting for my new interface I was just trying to get my feet wet with the on-board audio card. I had the same problem: sounded good when recording, sounded like chop suey (not the song) coming out. I’ll try the suggestions listed here.

Any other feedback much appreciated.

HP AMD64x2 dual-core, 2GB RAM, 80GB SATA (System) 500GB SATA (Home/Data).