[wdmaudiodev] Re: Obtaining unique identifier of Filter from its DispatchRoutines

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 18 Feb 2009 11:40:23 -0800

swapnil kamble wrote:
> Hi All,
>          I have created multiple instances of my Filter Centric
> AVStream driver by using a call KsCreateFilterFactory (), in which I
> give RefString name which matches with "wave name" in INF, and 
> FilterDescriptor table, which contains functions pointers related with
> Filter. Currently I am using DispatchCreate and DispatchProcess.
>       
> What I want is, whenever any of Dispatch Routine related to that
> filter is called, I want to know, which filter is responsible or
> associated with this call.
>
> Lets say I have 2 filters name VAD1,VAD2 with wave name WAVE1,WAVE2. I
> want to get either of these identifier from its DispatchRoutines to
> identify the filter correctly.

What's the purpose for this?  Each filter will have its own KSFILTER
object, and each callback is handed the appropriate KSFILTER, so you
will always be able to keep them straight in the dispatch routines

I *believe* you CAN get this information, but it will be ugly.  The
Create callback in the KSFILTER_DISPATCH table receives the
IRP_MJ_CREATE IRP that opened the file.  That IRP has a FILE_OBJECT, and
the FILE_OBJECT contains the namespace portion of the file name.

I am dubious that this is really the right way to do this, however.

-- 
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.

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