Choppy Audio From Wine, VirtualBox when Using Simultaneous Output

[Reuben Firmin]

Binary package hint: pulseaudio

Simultaneous output works fine from Gnome/Ubuntu. However, apps running under Wine or VirtualBox have poor performance and choppy/laggy sound when "simultaneous" is the preferred output.

I've verified that output to either one of the cards independently works fine - it's just the simultaneous option which introduces the bug.

[David Henningsson (diwic)]

First ensure that VirtualBox using the PulseAudio driver. If the bug is still present, please attach a PulseAudio verbose log according to https://wiki.ubuntu.com/PulseAudio/Log

What version of Ubuntu are you running?

[Reuben Firmin (reubenf)]

Thanks for the prompt reply David.

I'm using Ubuntu 9.10.

Your suspicion was correct - VirtualBox was indeed using ALSA. I thought that the ability to output to multiple soundcards simultaneously was one of the key benefits of the PulseAudio layer, am I wrong? And, further, that ALSA cannot output to multiple cards simultaneously, at least without a good deal of fiddling with asoundrc? If those assumptions are correct, then the bug would appear to be in Gnome - i.e. that the "output to both devices" option (system/preferences/sound/output) should not be applied to applications that bypass PulseAudio and use ALSA directly.

Wine is also using ALSA, as I guess you inferred (I did try out the patched wine to allow it to output to pulseaudio, but reverted to mainline a while back.)

[David Henningsson (diwic)]

It's a little more complicated than that. Setting Virtualbox to ALSA means virtualbox -> alsa-plugins -> pulseaudio -> alsa-lib -> kernel. I think the same goes for Wine.

And there's a bug in alsa-plugins that I've fixed (a new alsa-plugins for Karmic is in my PPA) that fixes stuttering issues, at least for some users. Perhaps that one will solve your problem as well?

[Reuben Firmin (reubenf)]

Yes, that does the trick, thanks.