No sound from USB audio interface

[kikigarel]

Hi,

I’m experiencing a weird issue with Virtualbox. I had to install a windows 7 32-bit (guest) virtual machine because some applications were no longer compatible with Windows 10 64-bit (host). I’m running version 5.2.12. I have installed the applications pack to improve USB support and I use a Motu Microbook IIc USB audio interface. The Motu driver is correctly installed, the hardware is correctly detected (by Windows, applications, etc) and “captured” by the VMware via a USB filter (USB 2 emulation, USB 3 doesn't detect the audio interface).

However, no sound comes out from the USB audio interface. When I try to play audio (sound file in foobar, streaming online music...) nothing happens and the files remain stuck at 00.00. When I switch the audio output device to the built-in speaker everything goes well. I get the following error message when I launch the Izotope (audio editing) application (see attached screenshot):

"Audio device error. The selected audio device cannot be opened. Please make sure it's not in use by another application and its drivers are up to date. ([0X9])"

error message 1.jpg (89.45 KiB) Viewed 4499 times

Am I doing something wrong? Is it a bug? Please help me. The support team at Motu told me it doesn’t surprise them as the hardware isn’t physically connected into the VM and therefore "can’t access the driver to run sound". Do you have any tips or leads to explore?

Many thanks in advance!

[michaln]

Am I doing something wrong? Is it a bug? Please help me.

Hard to say. Since your guest is Windows 7, you can try downloading Intel's xHCI drivers and installing them in the VM (you'll need the VirtualBox Extension Pack on the host and USB3 emulation enabled for the VM; see VirtualBox manual for details). Some USB audio interfaces are reported to work acceptably, which is no guarantee that another interface will work -- it all depends on the details of how the USB device and its drivers are implemented.

[kikigarel]

Hi Michaln,

Thanks for your reply. Actually I have already installed the extension pack and the audio interface is captured only with USB2 emulation (USB3 doesn't work with it, the hardware is not detected). I also tried to roll back to version 5.1.32, after which people experienced problems with audio interfaces, but it didn't change anything. The person from the Motu technical support told me there must be a conflict as the guest is trying to connect to the driver that is already being used by the host. But then the USB keyboard / mouse shouldn't work...? Please help me, I'm running out of ideas

Thanks in advance!

Gaël

[socratis]

Please read the following thread: USB basics and troubleshooting, all of the posts. If you still have a problem after reading through the whole thing, please follow the advice of the last post, #8: Asking for help and post the information requested.

[michaln]

Thanks for your reply. Actually I have already installed the extension pack and the audio interface is captured only with USB2 emulation (USB3 doesn't work with it, the hardware is not detected).

I don't quite understand what happens, but please keep in mind that xHCI is not the same thing as USB3. An xHCI USB controller handles USB3 and USB2 traffic, and xHCI is much more virtualization friendly than the older OHCI and EHCI designs. So even if you have a USB2 device, it will almost certainly work better with xHCI emulation--with the caveat that Windows 7 needs a vendor driver installed because it includes no xHCI/USB3 support out of the box (unlike Windows 8 and later).

[kikigarel]

Thanks for your help. I must say that installing the "Intel USB 3.0 eXtensible Host Controller Driver" in the Windows 7 guest partially fixed the problem as I now get audio playing through the USB audio interface. However, the sound is totally distorted/crackling/stuttering. It plays fine for 5 seconds, then it gets bad and disappears for 5 seconds, reappears and progressively gets better, and so on. It seems to be a common issue as many other users complain about it. I have rolled back to version 5.1.30 that is supposed not to be affected, but the problem is still there. I have allocated 3 cores and 10 gigs of RAM to the VM so I really don't know what's wrong.

[kikigarel]

I finally managed to capture the USB audio interface with xHCI

[michaln]

I finally managed to capture the USB audio interface with xHCI

That's good to hear. Is it now actually usable? And if yes, could you please list the exact model of your USB audio interface for future reference?

Re rolling back to 5.1: The problems with audio stuttering etc. were/are related to the audio hardware emulated by VirtualBox. Since you are directly passing through a USB audio device to the guest OS, the problems are completely different. Rolling back will probably just make things worse because you lose two or three fixes related to USB.

[kikigarel]

No, it is still unusable because the distorted output fluctuates (sometimes the sound is and remains perfect if I move the pointer at the same time, or if I resize the Foobar window, which is very odd!) but this is due to the VirtualBox issue. However I confirm the hardware is compatible. The USB audio interface is MicroBook IIc from Motu.