[wdmaudiodev] No sound out from MSVAD capture pin

  • From: "Yong Liu" <ly.didiom@xxxxxxxxx>
  • To: wdmaudiodev <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 2 Mar 2007 11:53:11 -0800

I have been working on this virtual audio driver for a while, and I got a
lot of helps from here during the development. Now I have problem in using
this driver as a audio capture device. Here is the structure of the driver.
It is a virtual audio driver, receiving audio data from a user
mode application, and send the audio data out as a capture device. Based on
MSVAD, the drive sent event to the application in the interval of 10 ms,
this was done by m_pTimer, m_pDpc and TimerNotify in MSVAD. As the
application received the event, it called DeviceIoControl via
IOCTL_KS_PROPERTY to send audio data to driver (10ms data). In the property
handler, audio data was passed to m_pvDmaBuffer which was allocated when
NewStream was created. Also the dma buffer size is 10 ms. Since it is
capture driver, I overwrited CopyTo to do nothing. In CopyFrom, I wrote:
      RtlCopyMemory(Destination, m_pvDmaBuffer, ByteCount);

As I ran the driver in GraphEdit, no sound out. But if I did nothing in
Copyfrom, there was sound like "sha, sha". What is wrong in copyfrom, or any
other error in the structure? Any suggestions are appreciated.


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  • » [wdmaudiodev] No sound out from MSVAD capture pin