[vbox-dev] audio issues

Frank Mehnert frank.mehnert at oracle.com
Thu Apr 27 07:30:20 UTC 2017

Hi Perry,

On Freitag, 21. April 2017 11:02:33 CEST Perry Halbert wrote:
> As of today r66644 from SVN, audio is much improved but not fixed yet.  
> The stutter is improved but now there are popping issues.  The 
> additional logging shows a greatly reduced amount of the stuttering due 
> to stream full but they still happen.
> Host Linux 64-bit guest Mint-17 64-bit and tried both ac97 and intel hd 
> audio. I sounds like the intel hd audio might be better than the ac97 to 
> my ears but can not provide empirical data to support the assumption.
> I don't do a lot with Windows these days but it appears that the audio 
> in a Win-7 guest has been acceptable all along if that is of interest to 
> you.

thank you for testing. Some status update regarding sound in trunk and in the
5.1.x branch:

At the moment the code between trunk and 5.1 drifts away a little bit. In
principle trunk has the more modern audio framework, in particular it moves
more audio work from the EM threads (the VCPU emulation threads) to separate
threads. This is good for the timing and therefore good for audio quality.
Trunk audio didn't change for some weeks (it still needs improvements),
therefore we are slightly surprised that you experience improvements with
the latest trunk updates. I'm also not aware of any recent VMM updates which
would improve timing...

The 5.1.x branch still uses quite old audio code. We don't want to do
fundamental changes in 5.1.x but we need to fix certain cases. Especially
we are aware that Windows 10 AU guests don't work well with 5.1.x (including
5.1.20). Unfortunately fixing this is more complicated and conflicts with
our goal to keep the changes in 5.1.x minimal. I can only say that we are
trying to improve the situation with Windows 10 AU+ guests but we still don't
have a final solution.

Kind regards,

Dr.-Ing. Frank Mehnert | Software Development Director, VirtualBox
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