[wdmaudiodev] Re: Problem getting MSVAD driver handle

  • From: "Jan M" <jan_m@xxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Wed, 14 Jul 2010 20:27:57 +0100

Hi Tim,

The handle will be used with DeviceIOControl() to do custom IOCTL.

Regards,

Jan

----- Original Message ----- From: "Tim Roberts" <timr@xxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Wednesday, July 14, 2010 8:06 PM
Subject: [wdmaudiodev] Re: Problem getting MSVAD driver handle


I am having a problem with getting a handle on the example MSVAD (Simple)
audio driver. It is installed using DevCon and working ok.

Using the example application code from
WinDDK\7600.16385.0\src\general\ioctl\wdm, I have tried the following:

 HANDLE hDrv = CreateFile(L"\\\\.\\MSVAD (Simple)",

GENERIC_READ|GENERIC_WRITE,
                                               0,
                                               NULL,
                                               CREATE_ALWAYS,
// Also tried OPEN_EXISTING
FILE_ATTRIBUTE_NORMAL, //
Also tried 0
                                               NULL);

Other paths tried:

L"\\\\.\\*MSVADSimple"
L"\\\\.\\MSVAD_Simple"

What path should I pass to CreateFile()?
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None of these.  The driver does not create a symbolic link, because
there's nothing you could do with it, anyway.  What do you hope to do
with this handle once you open it?

You open audio devices using audio APIs.  If you plan to send kernel
streaming requests directly, then you need to use the system device
enumerator (CLSID_SystemDeviceEnum) to fetch an IBaseFilter instance.
There are different instance file names for the filter and the various
pins, and the APIs know how to manage this.

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

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