state of spice and audio?

[Tom Horsley]

So I'm completely confused by how audio is supposed to work
with spice. The spice-space.org docs have various marketing
level blurbs talking about how audio is one of the channels
of data handled by the spice client, but playing with my
windows XP KVM machine on fedora 14, I can't get any audio
at all to play.

I'm also confused by all the examples showing I should start
qemu with an ac97 audio device. I would have expected an audio
equivalent of the video qxl driver (but what do I know?).

Can anyone clarify for me the state of spice and audio
(and maybe even give me a hit about how to get audio
out of the Windows XP virtual machine?).

[Dor Laor]

On 09/18/2010 03:38 AM, Tom Horsley wrote:
>  So I'm completely confused by how audio is supposed to work
>  with spice. The spice-space.org docs have various marketing
>  level blurbs talking about how audio is one of the channels
>  of data handled by the spice client, but playing with my
>  windows XP KVM machine on fedora 14, I can't get any audio
>  at all to play.
>
>  I'm also confused by all the examples showing I should start
>  qemu with an ac97 audio device. I would have expected an audio
>  equivalent of the video qxl driver (but what do I know?). 
qxl is paravirt GPU that was specifically created to provide advantages 
over the poor old Cirrus logic alternative.
For audio things are simpler, there is no need for pv device since the 
rate is usually slow - 44khz +- That's why full emulation is still a 
good idea and ac97 should be used.

>  Can anyone clarify for me the state of spice and audio
>  (and maybe even give me a hit about how to get audio
>  out of the Windows XP virtual machine?). 
ac97 is the device/driver pair. Without spice you should use a host 
'backend' like pulse. With spice, spice-server is the backend and it 
sends the audio directly to the spice-client that plays the actual stream.

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[Tom Horsley]

On Sun, 19 Sep 2010 10:42:14 +0200
Dor Laor wrote:

>  ac97 is the device/driver pair. Without spice you should use a host 
>  'backend' like pulse. With spice, spice-server is the backend and it 
>  sends the audio directly to the spice-client that plays the actual stream. 
OK, that is consistent with the examples, but no audio plays via
the client. The Windows machine clearly believes it has ac97
audio, and the volume is set to 100% and I can try playing
sounds, but nothing happens on the spicec side.

I'd expect the spicec client to play the sounds via the default
pulseaudio everything else uses on the machine where the
client is running (which in my case is the same as the KVM host).

Should I just submit a bugzilla on this?

[Tom Horsley]

On Sun, 19 Sep 2010 08:25:57 -0400
Tom Horsley wrote:

>  I'd expect the spicec client to play the sounds via the default
>  pulseaudio everything else uses on the machine where the
>  client is running (which in my case is the same as the KVM host).
>  
>  Should I just submit a bugzilla on this? 
I just went ahead and did it:

https://bugzilla.redhat.com/show_bug.cgi?id=635401

I see libasound linked with spicec, but there is
no indication it every tries to use it to play
anything.

[Gerd Hoffmann]

On 09/19/10 15:05, Tom Horsley wrote:
>  On Sun, 19 Sep 2010 08:25:57 -0400
>  Tom Horsley wrote:
>
> > I'd expect the spicec client to play the sounds via the default
> > pulseaudio everything else uses on the machine where the
> > client is running (which in my case is the same as the KVM host).
> >
> > Should I just submit a bugzilla on this?
>
>  I just went ahead and did it:
>
>  https://bugzilla.redhat.com/show_bug.cgi?id=635401 
[ also replying to the list so not everybody has to walk to bugzilla
   to figure what is going on ]

Yea, libvirt has no spice support (yet), so this road is a bit bumpy 
unfortunately.  We are working on it, F15 will be better ;)

libvirt sets "QEMU_AUDIO_DRV=none".  Which in turn will make qemu send 
all audio to /dev/null.  Setting "QEMU_AUDIO_DRV=spice" will make qemu 
send all audio to the spice client.  As you need a wrapper script anyway 
to enable spice you can easily stick this in there as well to make audio 
work.

cheers,
   Gerd

[Tom Horsley]

On Mon, 20 Sep 2010 09:52:00 +0200
Gerd Hoffmann wrote:

>  libvirt sets "QEMU_AUDIO_DRV=none".  Which in turn will
> make qemu send 
>  all audio to /dev/null.  Setting "QEMU_AUDIO_DRV=spice" will make qemu 
>  send all audio to the spice client.  As you need a wrapper script anyway 
>  to enable spice you can easily stick this in there as well to make audio 
>  work. 
Yep, that did indeed fix it (thanks for spotting what my eyes
apparently couldn't see - seems pretty obvious when pointed out :-).

Now that I got that far in my testing, I was able to add a
new (apparently random) bug:

https://bugzilla.redhat.com/show_bug.cgi?id=635900

The spice client crashed on me with a failed to parse message error
(but I couldn't reproduce it, even playing same video).