Re: [Qemu-devel] assigned EHCI USB headset not working

[Jan Kiszka]

On 2011-06-09 09:08, André Weidemann wrote:
> Hi Jan,
> 
> On 09.06.2011 08:53, Jan Kiszka wrote:
>> On 2011-06-09 08:19, André Weidemann wrote:
>>> Hi Gerd,
>>>
>>> On 08.06.2011 14:49, Gerd Hoffmann wrote:
>>>> Hi,
>>>>
>>>>> The sound device shows up under Windows7 and drivers are installed
>>>>> automatically. Unfortunately it does not work. All the players I
>>>>> tried,
>>>>> did not even start playing the sound file, although they detected the
>>>>> DirectSound Device.
>>>>
>>>> iso xfer's from usb-linux via ehci are flaky for reasons not yet
>>>> tracked
>>>> down.
>>>>
>>>> Any reason why you don't just plug in a virtual sound card? The HDA
>>>> emulation should work fine with win7.
>>>
>>> Using the hda driver was my first attempt. But the result was not very
>>> convincing. When playing mp3s inside the VM, I could hear music coming
>>> from the speakers, but the sound was very choppy and too slow. It was no
>>> joy listening to it.
>>
>> Does "export QEMU_AUDIO_DAC_TRY_POLL=0" before invoking qemu helps? It
>> depends on your host-side interface. Using ALSA here, it is generally
>> required.
>>
>> Note that this discussion rather belongs on qemu-devel.
> 
> Thank you very much. Setting the variable did the trick.
> Could this perhaps be included in the man page? I am sure there will be
> others who will eventually run into the same problem as I did.

It is a long-standing issue of QEMU that I always wanted to understand
but never found the time for. CC'ing malc, maybe he has a good idea how
to finally attack this.

Jan

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