[vfio-users] PCIe Sound Card VFIO Pass through Sounds Terrible (link to audio file)

[Jonathan Scruggs]

Hi all,

I have a PCIe sound card that I wish to pass through to a Windows 10 guest
using VFIO, but it sounds terrible.

Kernel: Linux Beast 4.7.5-gentoo #5 SMP PREEMPT Thu Sep 29 11:26:39 BST
2016 x86_64 Intel(R) Core(TM) i7-5930K CPU @ 3.50GHz GenuineIntel GNU/Linux

Qemu version: app-emulation/qemu-2.7.0-r4::gentoo

Libvirt version: app-emulation/libvirt-2.2.0

The sound card is:
09:00.0 Audio device: Creative Labs Sound Core3D [Sound Blaster Recon3D /
Z-Series] (rev 01)

The relevant part of the XML file is:
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x09' slot='0x00' function='0x0'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
function='0x0'/>
    </hostdev>

The Audio I'm trying to play: https://www.youtube.com/watch?v=jc8Mm5TtIhg

What it actually sounds like:
https://drive.google.com/file/d/0B12vXeyT8c8HZ0RqMmpnWDZUdXM/view?usp=sharing

To record the Audio, I plugged the cable into a recorder instead of going
through speakers or line in on the host to see if it was any other device,
but it sounds the same on all.

I hope you can help.
Jon
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