Re: [PATCH] audio/pwaudio.c: Add Pipewire audio backend for QEMU

[Dorinda Bassey]

Are there any additional features available when using the pipewire
protocol instead of pulseaudio or jack?

yes, Pipewire supports both use cases, It is more or less a hybrid between pulseaudio and jack.

Pipewire uses a much more accurate timing model for timer based scheduling.

Pipewire provides highly optimized audio processing paths.

Pipewire uses ACP(copy of PulseAudio card profiles), UCM devices, profiles, ports, soft/hw volumes, jack detection, it supports ALSA API and UCM profiles.

Are there any plans beyond audio?  pipewire does video too and gnome
screen sharing uses that.  Is it maybe possible to wire up the qemu vga
display and have pipewire send out qemu sound+display as video stream?

I don't know but It's worth considering.

Regards,

Dorinda.

On Wed, Feb 15, 2023 at 4:11 PM Gerd Hoffmann <kraxel@redhat.com> wrote:

> > What is the main advantage compared to using the ALSA backend? (I
> > assume pipewire depends on ALSA anyway on Linux)
>
> I think it does make sense to add Pipewire. Apparently it gains popularity.
>
> The main advantage of Pipewire is its interoperability: It allows you to
> connect apps with each other that only support a specific audio system. Say
> one app that only supports JACK, another app that only supports PulseAudio,
> another that only supports ALSA and so on. So it tries to provide a universal
> plug on a system for all.

We already have support for pulse, jack and alsa in qemu, so there are
already three different ways to talk to pipewire.  So the question
whenever adding yet another way makes sense is valid IMHO.

Are there any additional features available when using the pipewire
protocol instead of pulseaudio or jack?

Are there any plans beyond audio?  pipewire does video too and gnome
screen sharing uses that.  Is it maybe possible to wire up the qemu vga
display and have pipewire send out qemu sound+display as video stream?

take care,
  Gerd