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

[Jan Kiszka]

On 2011-06-09 17:13, malc wrote:
> On Thu, 9 Jun 2011, Jan Kiszka wrote:
> 
>> On 2011-06-09 09:08, Andr? Weidemann wrote:
>>> Hi Jan,
>>>
>>> On 09.06.2011 08:53, Jan Kiszka wrote:
>>>> On 2011-06-09 08:19, Andr? 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.
>>
> 
> Attack what exactly?

Sound output over (at least) ALSA is not smoothly working in polled
mode. It's similar to [1], which is yet unsolved.

Jan

[1] http://thread.gmane.org/gmane.comp.emulators.qemu/52365

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