[wdmaudiodev] Re: setting sample rate in the control panel in Vista
- From: Eugene Gavrilov <egavrilov@xxxxxxxxxxxxx>
- To: Uwe Kirst <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Tue, 30 Oct 2007 02:29:16 +0300
Hi Uwe,
>> * declare only current sample rate in the Vista control panel, and use
>> custom control panel for sample rate switch (it will be automatic for
>> external sources)
> That would be great, but how do you do that without unloading the
> driver? My understanding was so far that this is not possible. Please
> correct me if I´m wrong.
> Unloading the driver is not an option for me, because the driver has to
> control the hardware all the time the hardware is present. The driver is
> also needed for the other intefaces (ASIO / GSIF).
My driver is AVStream-based, not portclass-based, that's why it might
be a bit easier for me. On driver start-up, the driver reads current sample
rate from the device and creates filter factory + pins + data ranges
with a single sample rate. Vista shows single format in
its control panel, the control is grayed out, disabled. Whenever an
event happens (user changes hardware sample rate or opens
vendor-specific control panel), I perform the following:
* signal AVStream that device classes state is 'disabled' (this
terminates all pending DirectSound/WinMM sessions) - by using
KsFilterFactorySetDeviceClassesState
* _KsEdit() pin's data range, filter factory data range and change the sample
rate
* signal AVStream that device classes state is 'enabled'
This solves the problem with everything but Vista control panel :) It
keeps displaying previous sample rate, but also lists new one. If a
user selects new sample rate, old one disappears... However, WinMM
applications won't work until sample rate is changed manually. But
ASIO/GSIF clients are working properly, of course.
For PortClass driver it should be possible to achieve the same by
using IUregisterSubdevice interface.
I'm still unsure if this Vista behavior is correct. I suppose it is a
bug, because the control panel keeps listing the format no longer
supported by device and no longer manifested by the driver. Moreover,
even after reboot / disable-re-enable and similar events Vista
remembers the format. I wonder if this is caused by the specifics of
the audio format (our hardware uses 24-bit data packed into 32-bit
containers) - since the control panel checks 8-, 16-, and 24-bit
formats during initialization (I receive corresponding intersection
requests), but no 32-bit formats are enumerated.
Regards,
Eugene Gavrilov
Senior Software Engineer,
CEntrance, Inc.
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