[pve-devel] Audio support, dummy/none

[Aaron Lauterer]

Hi Gilou!

On 1/3/21 1:55 AM, Gilles Pietri wrote:
> Hi!
> 
> Happy new year to everyone, especially the devs working on Proxmox, it's
> still awesome in 2021 ;)
> 
> I'm interested in replicating a qemu audio setup that uses the dummy
> driver (called "none") on Proxmox, but the enum $audio_fmt
> (PVE/QemuServer.pm) for drivers only contains spice as a choice, which
> is all nice, but a bit restrictive!

May I ask what your use case is?

The reason why we currently only support the spice audio backend is that for other possible use cases, other (better / simpler) options exist.

Windows RDP supports audio by itself and if you need to play audio on the actual sound card it is simple to pass it through as PCI device to the VM.

> 
> Since this is used only (?) to generate the audio conf (through
> conf_has_audio), which generate the audio devices through audio_devs,
> which in turn generates both the -device param and the -audiodev
> backend,id=xxx, it seems there wouldn't be any side effect if we fed
> "none" instead of spice, as the id param is valid and works the same here.
> 
> I haven't tried patching that, but it might be that this would boil down to:
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index bca5669..54278e5 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -211,7 +211,7 @@ my $audio_fmt = {
>       },
>       driver =>  {
>          type => 'string',
> -       enum => ['spice'],
> +       enum => ['spice', 'none'],
>          default => 'spice',
>          optional => 1,
>          description => "Driver backend for the audio device."
> 
> And maybe, if we want to go further, we may want a bit of documentation
> also, maybe on the wiki… 

Is the current documentation in the admin guide [0] enough or do you mean more documentation on how to setup more advanced audio setups, such as with PA or ALSA?

> Also, though it's not my usecase atm, it might
> be interesting to add others backends as well, like alsa or pa. It was
> mentionned here:
> https://forum.proxmox.com/threads/audiodev-driver-pa-support.62317/#post-285020
> 
> However that will require second level options for the audio backends,
> which are not supported as it's coded.
>
> Cheers,
> 
> Gilou

All the best!
Aaron

[0] https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_audio_device