Audio-processing overloads processor and slows output to a stop

[J.L. Blom]

I'm running virtualbox on an AMD Phenom II 4-core, 4GB memory. Host Os is Ubuntu jaunty (9.04). The guest OS is Windows XP + SP2 which I run with one core enabled. I'm running a rather heavy application in the guest which use sound intensively.This application, Finale, is a music notation program which can play the score written. When I have a score of say 100 bars, and let it play then after a few bars, the tempo of playing diminishes until, instead of say 90 bpm (beats/min.) it slows to less then 10 (and then I cut it off). When I look at the load, one processor runs at 100% continuously. When I play sound in e.g.a youtube film, the load is much lower although considerable, approx. 75% of one processor (but it is of course video and sound) but the sound is equal throughout. I have used the program on an original Windows installation on a slow system and I didn't have this problem ( although the sound reproduction was imperfect due to memory limitations). The audio is the board-integrated audio controller VIA 1708S. Virtualbox host driver: OSS Controller: ICH AC97. This is the best setting as with Pulse-audio the sound is distorted and the choice Soundblaster16 (as host driver) doesn't work at all. It is very important for me to have it solved as I use the program on a daily base.

[Frank Mehnert]

Actually PulseAudio is the preferred host backend. When using this backend, is the sound always distorted (that is, when viewing youtube videos as well) or only when running your special application? I assume that your Ubuntu Jaunty host is up-to-date ...

[Philippe Verdy]

if you use VBOX for daily work, and you have these performance issues, the best you can do for now is to use the nulldriver emulation mode, or accept to have distortions in SB16 mode (possible clicks because of excessive delays when transfering virtualized audio data buffers from the guest to the host)

[Philippe Verdy]

you may also try by reducing the audio quality in the guest (avoid 32-bit mode, or go with 8-bit mode if 16bit mode is still using too much CPU). It's strange anyway that it blocks both the hist and guest, when you have a quad-core CPU (or may be this is caused by atomic operations that lock all cores at the same time during the virtualization)

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.