[gentoo-user] Optimum sound settings for QEMU VM?

[gentoo-user] Optimum sound settings for QEMU VM?

[waltdnes]

  I'm involved in beta testing Gstreamer 1.x support for HTML5 under
Pale Moon (a Firefox fork).  So far so good; it works.  I use a QEMU VM
for some building and testing.  Things work great on a real physical
machine, but audio absolutely sucks in the QEMU VM.  I get an annoying
warble-stutter and the playback seems a bit slower than it should be.
The same thing also happens with mplayer playing a .wav file, so it's
definitely not a Pale Moon browser problem.

  The VM gets 3 gigs of RAM (host has 8), 4 gigs of swap space, and 3 of
the host's 4 cores.  Resources should not be a problem.  Has anybody got
better performance?  If so, what are your kernel and sound card settings?

  I launch QEMU with "-soundhw hda".  Here are the "make menuconfig"
kernel config sound driver settings for the Gentoo guest VM.

    Device Drivers  --->


<*> Sound Card Support  --->


<*>   Advanced Linux Sound Architecture  --->


[*] PCI sound devices  --->
    HD-Audio  --->


<*> HD Audio PCI
(64) Pre-allocated buffer size for HD-audio driver
[*] Build hwdep interface for HD-audio driver
<*> Build Realtek HD-audio codec support
<*> Build Analog Device HD-audio codec support

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

[gentoo-user] [SOLVED] Optimum sound settings for QEMU VM?

[waltdnes]

On Mon, Mar 28, 2016 at 10:37:57PM -0400, waltdnes@waltdnes.org wrote
>   I'm involved in beta testing Gstreamer 1.x support for HTML5 under
> Pale Moon (a Firefox fork).  So far so good; it works.  I use a QEMU VM
> for some building and testing.  Things work great on a real physical
> machine, but audio absolutely sucks in the QEMU VM.  I get an annoying
> warble-stutter and the playback seems a bit slower than it should be.
> The same thing also happens with mplayer playing a .wav file, so it's
> definitely not a Pale Moon browser problem.
> 
>   The VM gets 3 gigs of RAM (host has 8), 4 gigs of swap space, and 3 of
> the host's 4 cores.  Resources should not be a problem.  Has anybody got
> better performance?  If so, what are your kernel and sound card settings?

  The problem appears to be the "sdl" flag.  It slows down things by
adding one more layer of middleware and overhead.  I also got rid of the
"gtk2" flag, for the same reason.  By building QEMU with "-sdl" and
"-gtk2", I get playback that is indistinguishable from playback on the
host.  Here is the build that works properly "emerge -pv qemu"...

[ebuild   R    ] app-emulation/qemu-2.5.0-r1::gentoo  USE="aio alsa curl
fdt gtk jpeg ncurses opengl pin-upstream-blobs png snappy ssh threads
usb vhost-net vnc -accessibility -bluetooth -caps -debug -filecaps
(-glusterfs) -gnutls -gtk2 -infiniband -iscsi -lzo -nfs -nls -numa
-pulseaudio -python -rbd -sasl -sdl -sdl2 -seccomp (-selinux) -smartcard
-spice -static -static-softmmu -static-user -systemtap -tci {-test}
-usbredir -uuid -vde -virgl -virtfs -vte -xattr -xen -xfs"
PYTHON_TARGETS="python2_7" QEMU_SOFTMMU_TARGETS="i386 x86_64 -aarch64
-alpha -arm -cris -lm32 -m68k -microblaze -microblazeel -mips -mips64
-mips64el -mipsel -moxie -or32 -ppc -ppc64 -ppcemb -s390x -sh4 -sh4eb
-sparc -sparc64 -tricore -unicore32 -xtensa -xtensaeb"
QEMU_USER_TARGETS="i386 x86_64 -aarch64 -alpha -arm -armeb -cris -m68k
-microblaze -microblazeel -mips -mips64 -mips64el -mipsel -mipsn32
-mipsn32el -or32 -ppc -ppc64 -ppc64abi32 -ppc64le -s390x -sh4 -sh4eb
-sparc -sparc32plus -sparc64 -tilegx -unicore32"


-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] [SOLVED] Optimum sound settings for QEMU VM?

[wabe]

waltdnes@waltdnes.org wrote:

>   The problem appears to be the "sdl" flag.  It slows down things by
> adding one more layer of middleware and overhead.  I also got rid of
> the "gtk2" flag, for the same reason.  By building QEMU with "-sdl"
> and "-gtk2", I get playback that is indistinguishable from playback
> on the host.  Here is the build that works properly "emerge -pv
> qemu"...

I have all gtk and sdl flags enabled and don't have problems with
the sound. 

--
Regards
wabe

Re: [gentoo-user] [SOLVED] Optimum sound settings for QEMU VM?

[waltdnes]

On Sat, Apr 02, 2016 at 06:55:29PM +0200, wabe wrote
> waltdnes@waltdnes.org wrote:
> 
> >   The problem appears to be the "sdl" flag.  It slows down things by
> > adding one more layer of middleware and overhead.  I also got rid of
> > the "gtk2" flag, for the same reason.  By building QEMU with "-sdl"
> > and "-gtk2", I get playback that is indistinguishable from playback
> > on the host.  Here is the build that works properly "emerge -pv
> > qemu"...
> 
> I have all gtk and sdl flags enabled and don't have problems with
> the sound. 

  Strange.  I kept making changes until it worked.  Now that it works,
I'll stop tweaking it.  Whatever works for you, or me.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] [SOLVED] Optimum sound settings for QEMU VM?

[wabe]

waltdnes@waltdnes.org wrote:

> On Sat, Apr 02, 2016 at 06:55:29PM +0200, wabe wrote
> > waltdnes@waltdnes.org wrote:
> >   
> > >   The problem appears to be the "sdl" flag.  It slows down things
> > > by adding one more layer of middleware and overhead.  I also got
> > > rid of the "gtk2" flag, for the same reason.  By building QEMU
> > > with "-sdl" and "-gtk2", I get playback that is indistinguishable
> > > from playback on the host.  Here is the build that works properly
> > > "emerge -pv qemu"...  
> > 
> > I have all gtk and sdl flags enabled and don't have problems with
> > the sound.   
> 
>   Strange.  I kept making changes until it worked.  Now that it works,
> I'll stop tweaking it.  Whatever works for you, or me.

I also disabled now gtk2, sdl and sdl2 because I don't really need it. 
I have to leave on gtk, because I run qemu in a gtk window. I don't 
notice any difference.

--
Regards
wabe

Re: [gentoo-user] [SOLVED] Optimum sound settings for QEMU VM?

[wabe]

wabe <wabenbau@gmail.com> wrote:

> waltdnes@waltdnes.org wrote:
> 
> > On Sat, Apr 02, 2016 at 06:55:29PM +0200, wabe wrote  
> > > waltdnes@waltdnes.org wrote:
> > >     
> > > >   The problem appears to be the "sdl" flag.  It slows down
> > > > things by adding one more layer of middleware and overhead.  I
> > > > also got rid of the "gtk2" flag, for the same reason.  By
> > > > building QEMU with "-sdl" and "-gtk2", I get playback that is
> > > > indistinguishable from playback on the host.  Here is the build
> > > > that works properly "emerge -pv qemu"...    
> > > 
> > > I have all gtk and sdl flags enabled and don't have problems with
> > > the sound.     
> > 
> >   Strange.  I kept making changes until it worked.  Now that it
> > works, I'll stop tweaking it.  Whatever works for you, or me.  
> 
> I also disabled now gtk2, sdl and sdl2 because I don't really need
> it. I have to leave on gtk, because I run qemu in a gtk window. I
> don't notice any difference.

I have to correct myself. Indeed there is a big difference. As I 
disabled the gtk2 flag, gtk3 is used now. Before, I sometimes had
some graphic glitches when I moved windows or scrolled window 
content in the guest machine. It seems that these glitches are not
there any longer. And it also seems, that graphics output is s little
bit smoother now. So THX for your post. :-)

--
Regards
wabe