Very large audio delay in Windows XP guest while CPU loaded at 100%

[dinosaur0]

I discovered a new bug in VirtualBox v5.1 that did not happen in v5.0 and older versions.

When running a Windows XP SP3 guest on a Linux host (with sound configured for ALSA on the host side and AC97 on the guest side), I get very long delays in games (1 to 3 seconds !) between the moment the sound is triggered and the moment it gets played: the higher the load on the CPU, the longer the delay.

Turning on HPET on the guest doesn't change anything...

I'm attaching a log of a short session when I started the VM and a game in it, clicked on menu items (which produce sounds at each click), got the delays each time, and shut down the game and the VM.

[dinosaur0]

See also this forum thread: ​https://forums.virtualbox.org/viewtopic.php?f=6&t=79505&p=371460#p371460

[Kosi]

I can confirm this behavior with Linux Mint 16 (Ubuntu based) host and Win7x64 guest. When I upgraded from 5.0.26 to 5.1.6 audio suddenly had a ~1.5s delay (both on start and stop) most noticeable on YouTube. The settings on the VM have not been modified. My CPU (neither host nor guest) have to show significant load to cause the issue. Updating the Guest Additions did not resolve the issue.

Downgrading to 5.0.26 removed the delay again (downgrade/reinstall of Guest Additions has NOT been performed after downgrade, still running with 5.1.6 additions).

[Kosi]

VBox config file for Win7 VM on Mint/Ubuntu host having audio delay on VB 5.1.6

[dinosaur0]

The bug still happens with VirtualBox v5.1.8

[dinosaur0]

From v5.1.10 changelog:

Audio: fixed a few 5.1.x regressions by using the audio code from 5.0.x until the audio overhaul is completed

This fixed the issue, indeed.

I'll add that v5.0.x audio always worked like a charm for me, so no need to break what's working just fine, don't you think so ?...

[Frank Mehnert]

Replying to dinosaur0:

I'll add that v5.0.x audio always worked like a charm for me, so no need to break what's working just fine, don't you think so ?...

Even the audio code in 5.0 is far away from working perfectly. There are many known issues and the overhaul in VirtualBox 5.1.x aims to overcome these problems. At the moment there are still too many problems left. But next time before we re-enable the new code we will let more users test and hopefully make more users happy.

[pentagonik]

Please have a try with the latest 5.2 test build 120822, which is located here: https://www.virtualbox.org/wikhttps://www.virtualbox.org/wiki/Testbuildsi/Testbuilds. Thank you!