[wdmaudiodev] Re: How to set a driver's default sampling frequency and num channels
- From: Tim Roberts <timr@xxxxxxxxx>
- To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Thu, 5 Jul 2012 14:33:34 -0700
Basileios Bu wrote:
>
> Thank you for your response. This is my first avstream driver, so
> while I've implemented this property for portcls, I've never done so
> for avstream. I'm obviously doing something wrong, because I never
> see it being called. This is my setup (perhaps the MinSize is wrong,
> but I've tried also with just sizeof(KSDATAFORMAT)):
> ...
> I've verified with the debugger that I've put this in correctly in
> my KSFILTER_DESCRIPTOR struct which I then pass
> to KsCreateFilterFactory. I've done this for both PCM render and
> capture, with neither being called? When would I see the handler
> being called?
I believe KS will handle this property on your behalf, based on the
KSDATARANGEs in your pin. Did you already show us your KSDATARANGE?
> Also, I have some general questions for KS property handlers:
> a) Is the only way to find the size of the output buffer from the IRP
> (pIrp->Parameters.DeviceIoControl.OutputBufferLength)?
Yes.
> b) Should I always set the irp->Information field for cases of success
> when I've filled the buffer, or also for cases when the buffer is NULL
> (I would return STATUS_BUFFER_OVERFLOW) and/or the buffer size is too
> small (STATUS_BUFFER_OVERFLOW)?
KS will handle some of this for you. It ensures that your output buffer
is as large as the size you specified in your KSPROPERTY_TABLE structure.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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