USB Audio device passthrough

[loiphin]

My understanding is that it affects all USB audio due to its single thread nature and not specifically to the Focusrite.

But my motherboard audio, which is also USB , works just fine?!?

 

[promoxer]

Motherboard means onboard right? How is that USB?

 

[loiphin]

Motherboard means onboard right? How is that USB?

Although its not physically connected to a USB port on your motherboard, your motherboard components (like bluetooth and audio) are connected by USB. You have two choices in motherboards when its comes to connectivity of internal components, PCIE and USB. I would argue most of your "lower bandwidth" stuff will always be connected by USB. Only the Ethernet adapter is normally PCIE.

Load up a linux distro and do a "lsusb" and a "lspci" on your machine and you shall see

 

[leesteken]

Motherboard means onboard right? How is that USB?

I understand the confusion, as all my motherboards since PVE 3 have had on-board sound connected via PCI(e) (with PCIe passthrough working fine).
The onboard audio device on Ryzen actually comes from the CPU via PCIe (with some components on the motherboard), like some of the USB controllers.
But is could just as easily be via USB. Both kinds of passthrough have their own caveats.

You have two choices in motherboards when its comes to connectivity of internal components, PCIE and USB.

Many onboard devices nowadays use USB or PCIe but some still use neither, such as touchpads, the onboard "speaker" and PS/2 keyboards.

 

[promoxer]

All my motherboards always had onboard audio connected via the I/O controller aka southbridge chip which usually hosts the USB but does not talk USB to the onboard audio. Which motherboard are you using exactly?

 

[leesteken]

All my motherboards always had onboard audio connected via the I/O controller aka southbridge chip which usually hosts the USB but does not talk USB to the onboard audio. Which motherboard are you using exactly?

This one (maybe one revision newer, different WiFi), where the audio device (10:00.4) shows up as a PCIe devices (in a iOMMU group coming from the CPU).
EDIT: Sorry, I did not realize you were asking @loiphin.

 

[promoxer]

I meant the motherboard that implemented onboard audio via USB (because I plan to stay far, far away)

 

[Jduluc]

I stumbled upon this thread and am also having plenty issues with my Focusrite Clarett 4pre USB, and passthrough from my Arch host to a Windows 11 Guest.

Although I am using Arch, I am pretty sure its the all the same (VFIO, QEMU) inner workings.

Sound in the guest works for a few minutes up to say 30 minutes. Then suddenly I get distortion, a bit crushing effect, beeping or silence. If I select another audio interface and then choose the Focusrite again, it normally works for a short time again, but the problem quickly reappears.

I have used the Focusrite Clarett on both the motherboard USB controller, passed through as a PCIE device to the windows guest, as well as a dedicated Startech PCIE USB 3.0 Card (Renesas chipset) passed through. Both exhibit exactly the same issues. The Startech card is considered the gold standard for PCIE USB cards and passhthrough.. it wasnt cheap!

So I am convinced that the USB implementation that Focusrite uses is very sensitive to timings or something like that, and just wont work.

My workaround for now is that I have passed through my motherboards audio card (Realtek ALC4082) to the windows guest instead, and it has worked flawlessly. Its just a shame I cant use my Focusrite Clarett

My focusrite uses built-in Linux drivers by Proxmox. My use case is just listening to music and short voice recordings as messages.

While I have no experience with ASIO as I never found the need for it (even before virtualization), I would say I'm sensitive to lags and there is none that I can detect. The only glitch is a few audible "clicks" when the machine as a whole is under load.

This is in comparison to what I will call garbled audio when passing thru USB.

I have near metal experience in passing guest audio to my focusrite on the host via VBAN

Hi, can you explain the process to do that?

 

[promoxer]

@Jduluc

1. It would be easier to familiarize yourself with setting up VBAN first, it basically sends audio over IP in realtime. https://vb-audio.com/Voicemeeter/vban.htm
2. Once familiar, you can send audio from VMs to proxmox