audio driver troubles on VM

[dbaker]

See my signature for details of my setup....

Until today, audio has been working fine on my Raring VM. I've had a few glitches here and there, but by and large I've been able to play sound in any app. However, I've ruined several VMs previously when I've installed a MIDI sequencer like qTractor which has caused some kind of audio driver conflict, killing sound system-wide. The only solution when this happened was to delete the VM and make a new one. So I've been very cautious with what audio-related software I install - until today.

I wanted to try out LMMS (Linux MultiMedia Studio) and I decided it was worth taking the risk. I didn't check my other audio apps (like Banshee and MuseScore) to make sure they were working immediately before installing it, but I assume they were because I've used them fairly recently. Anyway, on opening LMMS I discovered there was no sound output. It had started up with 'dummy sound', aka no sound output, so I switched that to ALSA (what I seem to be using system-wide) and restarted LMMS. Still no sound. I checked out the LMMS documentation and there was no mention of problems with NO sound, although plenty of mention of problems with BAD sound. Just to see if it might help, I followed the instructions under heading 2 on this page (http://lmms.sourceforge.net/wiki/ind...roubleshooting). It didn't make any difference.

At this point I decided to check if my other audio apps were still working. Guess what? No sound in any of 'em. I also checked Youtube. It seems the audio blackout is system-wide

I checked the system log and found the following. I don't know whether this is relevant or not, but it sure looks like it might be...

09/17/13 05:21:46 PM	kubuntu-VirtualBox	pulseaudio[2062]	[pulseaudio] pid.c: Daemon already running.
09/17/13 05:21:46 PM	kubuntu-VirtualBox	pulseaudio[2020]	[alsa-sink] alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write!
09/17/13 05:21:46 PM	kubuntu-VirtualBox	pulseaudio[2020]	[alsa-sink] alsa-sink.c: Most likely this is a bug in the ALSA driver 'snd_intel8x0'. Please report this issue to the ALSA developers.
09/17/13 05:21:46 PM	kubuntu-VirtualBox	pulseaudio[2020]	[alsa-sink] alsa-sink.c: We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail.

I should add that I've googled this issue and while lots of people appear to have problems with sound, it's always under different circumstances to mine (such as upgrading hardware or software). I haven't changed anything except installed an app that appears to have confused the audio drivers!

If anyone understands what's going on here and how to fix it, I'd really appreciate a step-by-step explanation. I'm a Linux newbie, so there's a lot of stuff I haven't learnt yet.

[SteveRiley]

First, read this -- Linux Audio Explained.

Next, study the following diagram:



After you've recovered from your vodka hangover, please try steps 1 through 6 on the Ubuntu Sound Troubleshooting page and let us know the results. You might also take a look at your Alsamixer configuration.

Also...please press Alt+F2, enter phonon, and post a screen capture of the resulting dialog box.

[dbaker]

Ok. I had no idea it was that bad O.O

All I've been able to determine, from following those troubleshooting instructions, is that it's not actually system wide - I made a new user and everything works fine. What's most incredible is that I was able to get sound working in LMMS and MuseScore at the same time - unheard of!

I'm no closer to understanding the cause of the problem though, except that I've seriously messed up the configuration. Is there some way I can just revert the audio configuration to 'factory settings'? I wasn't able to run the refreshing/reinstalling drivers step:

dorothea@kubuntu-VirtualBox:~$ sudo aptitude --purge reinstall linux-sound-base alsa-base alsa-utils linux-image-`uname -r` linux-ubuntu-modules-`uname -r` libasound2
sudo: aptitude: command not found
dorothea@kubuntu-VirtualBox:~$ sudo apt-get --purge reinstall linux-sound-base alsa-base alsa-utils linux-image-`uname -r` linux-ubuntu-modules-`uname -r` libasound2
E: Invalid operation reinstall
dorothea@kubuntu-VirtualBox:~$ sudo apt-get --purge install linux-sound-base alsa-base alsa-utils linux-image-`uname -r` linux-ubuntu-modules-`uname -r` libasound2
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package linux-ubuntu-modules-3.8.0-30-generic
E: Couldn't find any package by regex 'linux-ubuntu-modules-3.8.0-30-generic'

Here is the result of the phonon command. Doesn't seem to show much...


EDIT: ignore all that. I found out how to reset the configuration and it works now. But I CAN'T have musescore open at the same time as LMMS, it crashes. Oh well, I'm not likely to need to do that anyway. I just hope it doesn't apply to other audio apps as well. Going to test them all out now.

[SteveRiley]

Ok. I had no idea it was that bad

Just wait until you try to learn the graphics stack. It's worse

I wasn't able to run the refreshing/reinstalling drivers step:

...
E: Unable to locate package linux-ubuntu-modules-3.8.0-30-generic
E: Couldn't find any package by regex 'linux-ubuntu-modules-3.8.0-30-generic'

There are no packages that go by the name linux-ubuntu-modules-*. So that part of the advice is wrong, not sure where it would have come from.

Here is the result of the phonon command. Doesn't seem to show much...

It looks correct. Sometimes you'll see "PulseAudio Sound Server" as the lone object in that list; when you do, it means that the script that hooks PulseAudio to KDE didn't run. It's easy to fix that, just press Alt+F2 and run start-pulseaudio-kde.

But I CAN'T have musescore open at the same time as LMMS, it crashes. Oh well, I'm not likely to need to do that anyway. I just hope it doesn't apply to other audio apps as well. Going to test them all out now.

LMMS may simply not play well with Pulse, I dunno.

[dbaker]

Just wait until you try to learn the graphics stack. It's worse

Uh oh I wonder if that's why I still can't get the desktop cube effect to happen even though other desktop effects seem to be working? Although that's probably to do with the VM.

[SteveRiley]

Although that's probably to do with the VM.

Possibly...3D graphics in a VM can exhibit wonkiness.