VirtualBox 6.1.32 guests choppy sound after Slackware 15 upgrade

dracolich · 02-19-2022, 10:27 AM

Hello, guys, hopefully someone can offer some ideas. I've searched here and Google but not finding any recent ideas about this.

Up to two weeks ago my VirtualBox guests were fine, running on a Slackware 14.2 host with kernel 5.10.80 and pulseaudio. I could also have Audacious playing music on the host while playing games in a WinXP guest.

After upgrading Slackware to 15.0 and kernel 5.10.99, I had a problem at first with pulseaudio not finding any devices, and solved it by deleting the old /var/lib/alsa/asound.state. Now audio works fine on the host but all of my VirtualBox guests have terrible choppiness/stuttering using pulseaudio as the host driver and Intel ICH controller. Also, anything else playing sound on the host at the same time suffers the same. Below is my entire ~/.asoundrc:

Code:

pcm.pulse {
    type pulse
}

ctl.pulse {
    type pulse
}

pcm.!default {
    type pulse
}

ctl.!default {
    type pulse
}

I have not changed any host hardware or guest VM settings. The host is a 4-core cpu with 16GB Ram and a 2GB GTX750Ti. My XP and 7 guests are set for 1 cpu core at 100% cap with 2GB ram, legacy paravirtualization, and 64MB video ram with vboxsvga controller.

I have tried changing the host driver to ALSA, then Windows sounds are good but the games and other applications have no sound

I also tried reinstalling VB from the .run file to rebuild the kernel modules. One idea I read in an Arch forum suggested it is a timing issue caused by pipewire, but I do not have pipewire enabled. Other reddit posts and ubuntu forums suggest installing the guest additions, but I already have the 6.1.32 guest additions and extension pack installed.

dracolich · 03-21-2022, 05:31 PM

Since posting this 4 weeks ago I have tried alsa again and found that some games play sound while others don't. For example, Diablo and Diablo II have no sound

, while Mageslayer does have sound. A week ago I installed alien's multilib packages and wine 7.3, and I spent this past weekend updating all of my SBo packages now that the SlackBuilds.org 15.0 repo is up. None of that helped VirtualBox. I tried removing /opt/Virtualbox and the kernel modules from /lib/modules/5.10.99/blah/blah, then reboot and reinstall 6.1.32. Then I tried rolling back to 6.0.24, the last version with software virtualization support in case that is the problem, but it won't install because the kernel modules won't compile.

I could try recreating the VMs, hopefully using the same disk images, but it feels like something that should have a simpler solution.
The VMs are not laggy, just choppy sound.

dracolich · 03-23-2022, 01:41 PM

I finally found a simple enough workaround. Keeping the host audio driver as pulseaudio and changing the guests' device from ICH AC97 to SB16 fixed the choppy sound. Of course, the guest OS has to install SB16 drivers software.

Edit 03-27-2022: Switching to SB16 was not as effective as originally thought. Windows guest system sounds worked fine but in games the audio lagged by 1-2 seconds and voices sounded like a cassette tape at 50% speed.
I just now found that having pavucontrol open at the same time as a guest is enough to fix the choppy audio. While the guest is running if I close pavucontrol the audio immediately becomes choppy again, and when I reopen pavucontrol it is fixed again. So I made a little shellscript that opens pavucontrol before VirtualBox. Very weird...