[wdmaudiodev] Re: PC Audio Capture

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Fri, 08 Jan 2010 10:07:12 -0800

Sushma wrote:
>> Pre-Vista, it is possible to insert an audio class upper filter to
>> intercept the kernel streaming ioctls.  It is surprisingly difficult in
>> that situation to figure out what format the audio is in every case, so
>> plan some frustrating test time.
>>
>>     
>
> If the implement a audio class upper filter, what IRPs i need to look
> out for capturing the data.
>   

All kernel streaming transactions take place in internal ioctls,
IRP_MJ_INTERNAL_DEVICE_CONTROL.  Data gets transferred with
IOCTL_KS_READ_STREAM and IOCTL_KS_WRITE_STREAM.  You'll also need to
monitor the property exchanges through IOCTL_KS_PROPERTY.  There are a
lot of properties being exchanged.

If you don't have kernel streaming experience, you have a LOT of reading
to do.

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

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