Re: USB Audio Passthrough

Andrew Bobulsky
Sun, 02 Jun 2013 21:23:03 -0000

On Sun, Jun 2, 2013 at 10:17 AM, Gordan Bobic <gordan@bobich.net> wrote:

> On 06/02/2013 03:05 PM, David Sutton wrote:
>
>  I ''cheated'' in that I just passed one of the USB
controllers through to
>> my windows domU, then use a pair of USB headphones that I switch from
>> one port to another, depending on which VM i''m currently
using. Not had
>> any issues with it that way.
>>
>
> Yes, I was doing that for my keyboard and mouse passthrough to domU, but
> found that PCI passthrough on USB controllers was a bit hit-and-miss - they
> often wouldn''t come up properly when rebooting the VM. I switched
to using
> USB passthrough because of that, and since my audio PCI passthough
wasn''t
> entirely trouble-free, I thought I''d try the seemingly more stable
USB
> passthrough for that purpose.
>
>
> Gordan
>

Hello Gordan,

I haven''t tried USB passthrough on Xen yet, and I admit that I
haven''t
thought of trying, really, only because I''ve had such a poor experience
with it in the past on ESXi.  When I first undertook the task of getting
audio output from my VM (along with Keyboard/Mouse input!) USB passthrough
was my first idea... but it was just all crackly and terrible.  I was using
a quality device, too---a Sound Blaster X-Fi---I tried others, too, but
that didn''t seem to matter.

The next stop on getting this to work was instead to pass through a USB
controller, but the board I was using didn''t play nice when I did that.
 The onboard USB2''s were all hung off the PCI bus, which meant ESXi
wouldn''t let me pass them at all, and the USB3 controllers just flat
out
didn''t work.

I tried a commercial USB-port sharing product called USB
Redirector<http://www.incentivespro.com/usb-redirector.html>.
 It worked *very well* for both Audio and Inputs.  No latency, no
crackling.... but at about the cost of $40 per device...  Since I needed
twelve devices, I scrapped that idea.

The USB/IP project shows promise, but at the time wasn''t far along
enough
for me to consider using it.  I think that now, though, it might be worth
investigating.  If you want to work this out with software, I''d
actually
suggest looking into that the most!

I''m admittedly a little puzzled by the fact that you''re having
problems
with PCI passthrough of a USB controller, especially because you have an
Intel-based system... I always remember reports of that "just
working."

If you''ve got any more PCIe slots on your system, a USB3 add-in card
might
be the way to go... just make sure it doesn''t take power from a molex
plug
:P

Best Regards,
Andrew Bobulsky


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