Microphone delay in both Linux and Windows guests

[JackSpidy]

Relatively new to Proxmox and have been scratching my head over this for the past day.
When passing through my USB XLR Interface independently (tried by passing through the port and the specific device, and the entire controller) I get about a second (sometimes 2-3) of delay between speaking and that output actually being heard/registered, every other USB device performs fantastically, so I thought it might be a weird thing with XLR, so I fetched my old Blue Snowball out of the closet and I get the same level of delay from it, even though it's purely over USB with no kind of audio interface in between them.

Sorry if this is an obvious question but I really haven't been able to find anything on something like this, and I'm struggling here as this is kind of important as I'd like to have a Windows guest for gaming/discord, and a Linux guest that has access to the microphone.

(as an interesting addition, when I have my headphones plugged in over the USB XLR Interface, the output to the headphones has no delay, so this seems to be purely tied to microphones, not any other function of the interface.)

 

[leesteken]

When using SPICE, I do notice that sound sometimes gets delayed but how often it happens seems to depend on the physical USB headphones that I use. USB passthrough is not well-suited for high-bandwidth or low-latency. I have never had any such issues with USB audio devices when doing PCIe passthrough of a USB controller, but I assume you already tried that. High quality audio in a VM might be difficult because of timing issues (since the VM is not in control), so make sure to leave lots of CPU and memory headroom.
Do you see a high CPU overhead when using the USB microphones maybe? Some USB devices are constantly disconnecting and reconnecting due to incompatibilities between (cheap) devices and controllers. No errors in the Proxmox Syslog (or journalctl)?
Do your devices work on Linux VMs? Then you could try booting your Proxmox with an Ubuntu Live installer (without installing it) and see if it is Proxmox or VM specific or happens on this physical system as well.

 

[JackSpidy]

When using SPICE, I do notice that sound sometimes gets delayed but how often it happens seems to depend on the physical USB headphones that I use. USB passthrough is not well-suited for high-bandwidth or low-latency. I have never had any such issues with USB audio devices when doing PCIe passthrough of a USB controller, but I assume you already tried that. High quality audio in a VM might be difficult because of timing issues (since the VM is not in control), so make sure to leave lots of CPU and memory headroom.
Do you see a high CPU overhead when using the USB microphones maybe? Some USB devices are constantly disconnecting and reconnecting due to incompatibilities between (cheap) devices and controllers. No errors in the Proxmox Syslog (or journalctl)?
Do your devices work on Linux VMs? Then you could try booting your Proxmox with an Ubuntu Live installer (without installing it) and see if it is Proxmox or VM specific or happens on this physical system as well.

I have tried passing through the controller in it's entirety to the vms, and this did result in the windows guest having improved latency (around a quarter of a second consistently instead of 1-3 seconds of delay, usable enough for how much trouble its been) linux guests however still have a horribly long delay even with the entire controller passed through. I've now tested on both bare windows and bare linux, both with identical hardware and software configuration without any delay present. The big headscratcher for me here is that I plugged my headphones into my XLR interface for audio output (it has a less-than stellar amp/dac built in) and that has 0 delay, so it seems to exclusively apply to audio input from microphones, regardless of whether it's a direct USB microphone like the snowball or an XLR microphone, they both experience equal delay. With Linux guests, and the only consistency I can pin down between the Arch install and the PopOS install I've tried is Pipewire, maybe PulseAudio would provide a better result? also Journalctl nor the actual Proxmox error log outputs anything out of the ordinary. I'm also not noticing any kind of CPU or memory limitations on host or guest, both have plenty of memory and CPU power to play with (I have a 5900x and 32gb of ram, the guest is only using 8 cores and 16gb of memory, I've also tried running a guest with 4 cores and 8 gb of ram with the same results, the host always has good amounts of overhead in my current usecase)