Scratchy Audio in Vista Guest

[slackcc]

Hi all,

I recently installed VirtualBox (v. 2.0.6) under LinuxMint (2.6.24-16-generic kernel) and I'm finding that audio playing from within the guest (Vista Ultimate) is very scratchy.

I'm running the VM on a separate physical disk drive and have 512MB RAM allocated. And I've tried all 3 audio adapter settings on the VB side, PulseAudio seems to be the worst and ALSA and OSS seem to be about equal.

Has anyone else run into this problem and found a solution?

Thanks,

Chris

[Sasquatch]

If PulseAudio gives some response, that means that you run PulseAudio as sound server. Check the settings of it. By default (on Ubuntu, and Mint is Ubuntu), these settings are not optimal. You may need to increase the buffer size and amount of buffers to get better sound quality.
You can also decide to remove PulseAudio completely and stick to Alsa.

[slackcc]

That seems like the right direction to go in, it sounds like a buffering issue of some sort. Could you point me to where I might adjust the buffer sizes or give me an idea of how I might go about getting the pulse settings to be more optimal?

I've run Linux servers for years but audio doesn't frequently come up given the lack of sound cards and speakers and I think the last time I setup a Linux desktop system with audio running was around 1993, things have changed a bit since then So I'm a bit out of my element in this one.

Thanks,

Chris

[Sasquatch]

Check the PulseAudio site. Should be www.pulseaudio.org but I'm not sure.

[mark_orion]

I had similar problems with recording (microphone input) with pulse and an XP guest. XP recorded too slow and distorted. I could solve the problem by setting up ALSA to use pulseaudio by default. This can be done by entering
asoundconf set-pulseaudio
or by setting up an .asoundrc file in your homedirectory:

pcm.!default { type pulse }
ctl.!default { type pulse }
pcm.pulse { type pulse }
ctl.pulse { type pulse }

Now I can use the ALSA driver in Virtualbox and the output / input is still routed through pulseaudio.

[tshann]

I was having scratchy sound in these VM's using alsa. Then, I used the suggestion of mark_orion: asoundconf set-pulseaudio
After that, I set the VM to pulse, and rebooted the guest. Boom! the sound is crystal clear. So if there is a config file I can set that command in, I should have good sound in VM's from now on. Coolio!

Thanks for the suggestion mark, appreciate it. I'll probably look into the other suggestions and the config file he suggests (.asoundrc) and perhaps just put that single command in that config file. But for now, it's great to have non-scratchy sound. Awesome!
Peace

[eha1990]

@ tshann and mark_orion: Thank you for your suggestions on how to fix the problem with scratchy sound when running Windows XP as a guest OS in Ubuntu. I added the following to my .asoundrc file:

pcm.!default { type pulse }
ctl.!default { type pulse }
pcm.pulse { type pulse }
ctl.pulse { type pulse }

Saved my changes and set the Audio for Windows XP in VirtualBox to Pulse audio and it competely fixed my problem with audio sounding scratchy when played on the Windows XP guest OS. I thought it was some sort of buffer problem as well.

Thank you for the suggestions, I wanted to let you both know that your recommendations solved my problem.

[owain]

That's what I've got in .asoundrc already, so no luck there. However, I did notice a while ago that one program, which had an option to work at 48KHz rather than 44.1KHz, could play clear audio with this. So I wonder whether it's to do with resampling, as both my internal and USB soundcards work at 48KHz? (Being on a slow laptop hard drive coupled with resampling, I mean...)

[fmcdavid]

I played with everything to get the cruddy sound working. Tried different sound setups on the host, recompiled the kernel to change the timer setting from 100 (went to 1000...no luck, better maybe, but not good enough). Finally, I punted and set the number of cpus to 1 and turned off 2d acceleration. Eureka! One or more of all that was certainly not necessary, but I'm not backtracking...it's fine. Thought I'd post in the name of "something else to try"

[fmcdavid]

setting things to 1 cpu worked worked pretty well. I don't think acceleration mattered.

Upgrading to bleeding edge ubuntu kernel 2.6.32 seemed to help a little (required new X packages to keep things working).

But the weird thing is that, as long as I have 'pavucontrol' running, audio in the Win7 guest is almost tolerable and when I close it, it degrades back to unusable.

[fmcdavid]

This page has some hints for improving pulseaudio performance as well. Specifically, setting default-fragment-size-msec = 5 in /etc/pulse/daemon.conf has greatly helped.

http://fedorasolved.org/Members/fenris0 ... orkarounds

[fmcdavid]

Last post on this topic. Everything I did (past few posts) was tested using Netflix player and I'm pretty sure I managed to squeeze every ounce of performance out of it because it really is _almost_ watchable now. After being a bit discouraged messing with it all night, I tried playing some of the media files that win7 installs by default and was blown away. Sound is now flawless. I had tried them at the start of this exercise (just after getting sound working using AC97 driver and OSS host audio in ubuntu 10) and I was seeing broken audio comparable to the netflix player's cruddy performance (now somewhat improved).

To summarize what I did to get audio working:

* recompile host kernel changing timer setting (under processor type menu) from 100Hz to 1000Hz (possibly overkill...saw recommendations for 250Hz)
* drop to 1 cpu (possibly not necessary...definitely helps netflix player)
* Upgrading to bleeding edge ubuntu kernel 2.6.32
* upgrading x packages via this ppa: http://ppa.launchpad.net/xorg-edgers/ppa/ubuntu
* ensure 'pavucontrol' is running (seems like a hack, but it's very necessary for me)
* use pulseaudio atop alsa as sound system (and select pulseaudio in vm settings)...making this happen required some work beyond scope of post
* for me, since I have an intel hda-based card, follow steps in "If you have an Intel HDA card" section in http://fedorasolved.org/Members/fenris0 ... orkarounds
* change /etc/pulse/daemon.conf as follows:
realtime-scheduling = yes
default-fragments = 8
default-fragment-size-msec = 5

If someone who understands this stuff better than me can clean this up (to remove need for running pavucontrol, for instance), I think this would make a great addition to the faq.

One thing worth noting, where netflix is "almost watchable", hulu audio is flawless...framerates are probably comparable.