Q Light Controller+

Hi all - I'm hoping someone can give me a hand trying to solve this issue. I tried using QLC+ a couple months ago and could never get the audio trigger factory to work properly or find anyone who could help. I gave up in frustration, but have come groveling back to try once more to get it working, as I'd really like to be able to use QLC+, but absolutely need the audio trigger part to work.

I decided to wipe the computer and try starting again from scratch, with a fresh install of Ubuntu 12.04 LTS, 32 Bit, and a fresh install of QLC+ 4.5.0. I used the standard Desktop version of Ubuntu this time thinking my issues may have been tied to the minimal install version before. I also hoped the new version of QLC might help. The problem I'm having is certainly different, but I still can't get it to work.

I've started up qlcplus via the console, to aid in debugging. I add a fixture. I then to to input/output and select my DMX USB PRO for DMX output, and HDA Intel - AD198x Analog for Input and Output under Audio. I then go to the virtual console and add a new audio trigger. I go to properties and name it test, then for volume bar I select DMX, go to my fixture, and check the "Fade" box next to the master dimmer channel. I hit OK, switch to operate mode, and press the button with the green check mark.

The program then crashes, and this is what I see in the console:

qlcplus: pcm.c:1310: snd_pcm_readi: Assertion `size == 0 || buffer' failed.
Aborted (core dumped)

I've tried all kinds of different things I can think of, but the result is always the same - instant crash.

To test things a bit, I installed Audacity. In Audacity, the Audio Host is set to ALSA, and the input is set to pulse: Mic0. It's also set to stereo. I can make a recording and it picks up the sound perfectly.

Here is the contents of the ALSA debugging script, which I hope gives lots of relevant info that might help troubleshoot the issue:

[MC - EDIT] Log attached

Thank you to anyone who can help!

Hey, please do not paste extremely long logs like you did. I converted it to an attachment.
Now, I suspect you're not telling us the whole truth as Ubuntu 12.04 LTS (which I use every day at work) has kernel 3.2.0, while you installed kernel 3.8.0 which has been introduced in ubuntu 13.04.

The crash seems to be appearing inside ALSA and not QLC+. pcm.c is not a QLC+ file.
Anyway, version 4.5.0 has the audio device selection in input/output panel. Could you check if that makes any difference ?

Thanks for the response!

I'm not sure what you're trying to accuse me of regarding Ubuntu and the kernel version. I went to ubuntu.com, clicked on Download Ubuntu, Ubuntu Desktop, and selected 32bit under "for extended support" and downloaded 12.04. If I go to Settings > Details, it says "12.04 LTS". If I open a terminal and type "uname -r" it says 3.8.0-29-generic. I didn't do anything special at all. Maybe your computers at work just need to have updates installed or something. I'm just trying to give you all possible information, as requested in your sticky, to help troubleshoot the issue.

However, your suggestion regarding the audio device selection under input/output has resolved the issue! I went in and removed the check-mark from my sound card, so that nothing is selected/checked at all on the audio page, and now everything works as expected.

To be honest, this is pretty unintuitive. Reading the documentation on the site I got the impression that I was supposed to select my sound card on this screen. I'm not sure why the page exists at all if checking them causes the program to crash, regardless of what the pcm.c file is.

I'm not trying to accuse you, I just found weird you had a 3.8.0 kernel installed.
I use Ubuntu since more than 5 years and I know they don't change kernel so easily cause it could break a lot of things.
In the end I found the explanation. If you install the original 12.04 or 12.04.1 you won't get any kernel update. 12.04.2, instead, has kernel 3.5 while 12.04.3 has kernel 3.8.
So, what I've got at work is correct, since we installed the first 12.04.

"To be honest, this is pretty unintuitive. blah blah...". Now, who's trying to accuse who ?
If you can do better than that, download the sources and be my guest.

I get the samme error message on a thinkpad. Arch running kernel 3.11 and 3.12.

Could this have to do with pulseaudio?
Try running with pulseaudio disabled, like so:

pasuspender qlcplus

It fixes it for me but breaks my music player