[Qemu-devel] Re: [PATCH] alsaaudio: increase default buffer sizes

[malc]

On Thu, 8 May 2008, Jan Kiszka wrote:

> malc wrote:
> > On Tue, 6 May 2008, Jan Kiszka wrote:

[..snip..]

> And those suffer audibly if you increase QEMU_ALSA_DAC_BUFFER_SIZE?

The latency becomes noticable the audio should be okay.

> > > > > > you and this other user on some (kvm was it) mailing list there are no
> > > > > > huge outcries of dissatisfaction, then again i'm not sure how many
> > > > > > people
> > > > > > use ALSA+QEMU or QEMUs+AUDIO in general.
> > > > >
> > > > > I don't think many users are actually running QEMU (or KVM) against
> > > > > ALSA. You have to
> > > > > - manually enable it during configure
> > > > > - pass QEMU_AUDIO_DRV=alsa (OSS remains default even if ALSA is on - I
> > > > >   ran into this trap first.)
> > > >
> > > > I don't see how it's a trap. You can also enable esd or fmod drivers
> > > > in configure along with alsa, which one should be the default?
> > >
> > > For sure, you need this mechanism with >1 audio backends being enabled
> > > in parallel. It's just the question how one is supposed to find out
> > > about this additional requirement:
> >
> > Being enabled? Did you mean being built in? And what do you mean by
> > mechanism, mechanism to do what exactly?
>
> Yes, I meant built-in.
>
> > > $ grep -r QEMU_AUDIO_DRV qemu
> > > qemu/audio/audio.c:        "  set QEMU_AUDIO_DRV=wav\n"
> > > qemu/audio/audio.c:        "  export QEMU_AUDIO_DRV=wav\n"
> > > qemu/audio/audio.c:        drvname = audio_get_conf_str
> > > ("QEMU_AUDIO_DRV", NULL, &def);
> > >
> > > Am I missing some reference? Then sorry in advance.
> >
> > What is the question?
>
> Such kind of documentation is not for wimps. You know where to find and
> why to use it, but does the average user do?

Sorry, i still do not understand the actual question you are/were asking.

> > [..snip..]
> >
> > > Well, probably configurable as well with compat-OSS (real OSS is dead on
> > > Linux). The fact is that - not only for me - this sharing does not work
> > > out-of-the-box with OSS, while it does with ALSA. Don't ask me why, I'm
> > > not an expert on this, I'm rather looking at it from a "normal" user
> > > perspective.
> >
> > It doesn't with ALSA on this machine, and on the machine next to this
> > one, and on machine that lies on the floor. It boils down to how ALSA
> > was configured by distribution maintainers.
>
> Chances are generally higher that broken ALSA setups are reported and
> fixed than broken OSS emulations.

There's nothing broken about it. Enabling dmix, thus degarding quality
and speed, is not what some may elect to do.

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