I've built the example SwapAPO.dll from Microsoft, and wanted to have
that as a starting point for my own APO.
I've modified the following "FxProperties" registry keys for my device
in order to "hack" into the audio pipeline:
This is because the SwapAPO.dll source defines the above GUIDS for MFX and SFX:
and Microsoft documentation:
I've restarted the Windows audio process, and attached the debugger to
However, when I playback some audio, SwapAPO.dll is not loaded. What I
see loaded are:
Have I modified the right registry keys?
Sorry for my ignorance, I am new to this.
On Wed, Dec 16, 2020 at 7:33 PM Matthew van Eerde
APOs are expected to be loaded in two circumstances:
Audio effect queries
APOs are loaded for streaming if one of the following property keys is set:
Otherwise, they are loaded only for effects queries; such an APO is called a
“proxy APO” because the actual processing is done elsewhere.
To debug the operation of an audio processing object, you would attach a
user-mode debugger to the audio device graph isolation process audiodg.exe.
From: Danijel Domazet
Sent: Wednesday, December 16, 2020 10:18 AM
Subject: [EXTERNAL] [wdmaudiodev] Microsoft SYSVAD example audio driver: are
I installed Microsoft's SYSVAD example audio driver with APOs, but I
am not sure if the APOs are working.
I have done the steps as in the SYSVAD documentation:
- "devcon install ComponentizedAudioSample.inf
Root\Sysvad_ComponentizedAudioSample", and received a message "Drivers
- Right clicked on ComponentizedAudioSampleExtension.inf and
"install". After some time a message box popped-up saying the install
- Right clicked on ComponentizedApoSample.inf and "install". Waited,
but no pop-up message box appeared as in step 2, so I am not sure this
step finished successfully.
What I see in the Device Manager is:
- under Sound, video and game controllers: "SYSVAD (with APO Extensions)"
- under Software components: "Audio Proxy APO Sample"
- under Audio inputs and outputs: "Headphones (SYSVAD (with APO
extensions))", and other devices too with the similar name.
Is that all I should see?
I tried to check if all is working: I played back some audio, and
found the wav files were dropped at "C:\STREAM_HOST_*.wav", which
means the driver is working.
However, my goal is the APOs.
I don't see anywhere in the sound device properties any enable/disable
checkboxes for the APOs?
Is there a way to check if APO components are correctly installed and active?
I also set-up the WinDbg host-target PC debugging session, and managed
to break into the sysvad code, but only into TabletAudioSample.sys and
not into and of the APOs (SwapAPO.dll, KWSApo.dll, DelayAPO.dll).
Any help most appreciated,
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