[wdmaudiodev] Re: for help in implementation virtual audio driver

  • From: "Jeff Pages" <jeff@xxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Thu, 20 Jul 2006 17:22:12 +1000

If you're trying to send standard audio data into MSVAD, why are you trying to 
access it through a device interface rather than using one of the audio APIs 
such as waveOutOpen and waveOutWrite?

  ----- Original Message ----- 
  From: Weiji Zheng 
  To: wdmaudiodev@xxxxxxxxxxxxx 
  Sent: Thursday, July 20, 2006 2:49 PM
  Subject: [wdmaudiodev] for help in implementation virtual audio driver


  I am developing one project, that is, PCM data is transfered into MSVAD by 
usr mode, and MSVAD then put these PCM data into another application based on 
DirectSound, such as Skype, that means MSVAD will be open simultaneously both 
the applications.

  Actaully, I encounter the same question as following: 

  1. how can I get the handle of the MSVAD(Simple)? 
  2. I tried to use IoRegisterDeviceInterface() in AddDevice() of 
MSVAD(Simple), and then in my user mode application I use 
SetupDiGetDeviceInterfaceDetail() and CreateFile() to get the handle of the 
MSVAD device. It seems that I can get the handle of the MSVAD(Simple), but the 
Graph Edit con not find any device about MSVAD, Do you have any idea about 

  Maybe the implementation in IRP_MAJOR_CREATE is one key.

  //dispatch function
  extern "C"
      IN      PDEVICE_OBJECT  pDeviceObject,
      IN      PIRP            pIrp
   PIO_STACK_LOCATION IrpStack = IoGetCurrentIrpStackLocation(pIrp);
   DPF(D_TERSE, ("[enter PCP_Create]"));
   DbgPrint("the Flags is 0x%x\n", pIrp->Flags);
   DbgPrint("the RequestorMode is 0x%x\n", pIrp->RequestorMode);
   if(pIrp->RequestorMode == 0x1) //my own application
   {// Complete successfully
    pIrp->IoStatus.Status = STATUS_SUCCESS;
    pIrp->IoStatus.Information = 0;
    IoCompleteRequest(pIrp, IO_NO_INCREMENT);
    return STATUS_SUCCESS;
   else //Graph Edit
     // Pass the IRPs on to PortCls
     ntStatus = PcDispatchIrp( pDeviceObject, pIrp );
     DbgPrint("success to open device\n");
     DbgPrint("fail to open device\n");
    return ntStatus;

  But when I run own application(not Graph Edit), the system crash!

  so would you please give me some advice.

  thanks for any help.

  best regards

  --weiji zheng


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