Greetings audio gurus!
I am reaching out to you as I am looking to incorporate a proprietary DSP
algorithm within a windows driver. This is my first experience with windows
driver development, and I have been doing some reading, in particular:
https://docs.microsoft.com/en-us/windows-hardware/drivers/kernel/introduction-to-wdm
<https://docs.microsoft.com/en-us/windows-hardware/drivers/kernel/introduction-to-wdm>
https://docs.microsoft.com/en-us/windows-hardware/drivers/audio/wdm-audio-architecture--basic-concepts
<https://docs.microsoft.com/en-us/windows-hardware/drivers/audio/wdm-audio-architecture--basic-concepts>
https://docs.microsoft.com/en-gb/windows/win32/learnwin32/module-2--using-com-in-your-windows-program
<https://docs.microsoft.com/en-gb/windows/win32/learnwin32/module-2--using-com-in-your-windows-program>
https://docs.microsoft.com/en-us/cpp/atl/active-template-library-atl-concepts?view=vs-2019
<https://docs.microsoft.com/en-us/cpp/atl/active-template-library-atl-concepts?view=vs-2019>
From my reading, I have understood that software DSP is handled in ATL
COM-based objects known as audio processing objects which exist in the
user-mode Audio Engine which communicates with the drivers on the kernel-side.
As a result I have begun editing the SYSVAD example project, in particular the
Swap APO. The DSP algorithm runs on a proprietary software framework, and to
test whether everything works correctly I have created an identical channel
swap example with it and incorporated it within the MFX swap apo example. My
testing setup uses a virtual box VM as the target, through which I use vmmon
with windbg for debugging (Setup based on the steps at
https://www.youtube.com/watch?v=XUlbYRFFYf0&list=PLZ4EgN7ZCzJx2DRXTRUXRrB2njWnx1kA2
<https://www.youtube.com/watch?v=XUlbYRFFYf0&list=PLZ4EgN7ZCzJx2DRXTRUXRrB2njWnx1kA2>).
Both host and target computers are 64-bit windows 10.
I seem to be running into issues with this simple example - whenever I switch
on the audio enhancements for the sysvad driver (which should apply the channel
swap using our internal framework) a window pops up saying that “Windows has
detected that audio enhancements for the following device are causing problems:
[sysvad device name]. Audio enhancements for this device have been disabled.
Would you like to reenable?”. As an initial step, I have included several
“OutputDebugString” string calls to print some output to the debugger but this
doesn’t seem to show through dbgview (run on target machine with administrator
permissions with all capture types selected under capture menu). Any
suggestions on what I have to do to see this output? I have also put in several
OutputDebugString calls within the unaltered sysvad example and similarly I
cannot obtain any debugging output. Also, I have added
“DisableProtectedAudioDG” as a DWORD and set it to 1 in
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Audio but this has
not helped.
Many thanks guys. I understand that you’re all volunteering to help on this
mailing list, so any clarifications are much appreciated!
- Joey
