FiltergAPO

development

requirement

1. LibrosaCpp
2. libtorch

thanks

This project is implemented by adding functions to MinimalAPO published in Equalizer APO. The readme of the original MinimalAPO is below.

Preparation steps:

1. Build the project for your OS architecture (Win32/x64).
2. Register the APO by opening a command shell with Administrator privileges in the corresponding build directory (e.g. x64\Debug) and typing regsvr32 FiltergAPO.dll
3. Open regedit, go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Audio and create a DWORD value named DisableProtectedAudioDG with value 1 to allow unsigned APOs to run.
4. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\MMDevices\Audio\Render and find your default audio device by looking at the Properties subkeys. In the FxProperties subkey of the device create or change the value for {d04e05a6-594b-4fb6-a80d-01af5eed7d1d},1 to {0129658B-8ED4-47E7-BFA5-E2933B128766}. If there is the value {d04e05a6-594b-4fb6-a80d-01af5eed7d1d},5 then set that instead.
5. Go to the Sound control panel and make sure that audio enhancements are enabled for your device.
6. Open a command shell with Administrator privileges, type sc config audiosrv type= own and reboot to make the system start the audio service in a separate process. Otherwise the APO DLL will likely be permanently locked until reboot even when the audio service has been stopped.

Development steps:

1. Launch an audio application and verify that the APO is effective. Without changes to the processing method, you should hear some noticeable distortion.
2. Change the APO code. You might want to start with the method FiltergAPO::APOProcess, where the actual audio processing happens. You can debug by attaching to audiodg.exe.
3. Stop the Windows Audio service (AudioSrv) to unlock the FiltergAPO.dll.
4. Build the Visual Studio project to overwrite it with the new DLL.
5. Start the Windows Audio service again and continue with step 1.

Necessary steps before release (just some hints):

1. Change the class name FiltergAPO.
2. Change the registration properties at the top of FiltergAPO.cpp (change name and insert your copyright statement).
3. Use the GUID generator (C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\Tools\guidgen.exe) to generate your own GUID and place it into the __declspec (uuid(...)) declaration in FiltergAPO.h.

Removal steps:

1. Revert the changes you made to the FxProperties subkey of the default audio device (see preparation step 4). If you can't, you can also just reinstall the audio device driver.
2. Open regedit, go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Audio and remove the value named DisableProtectedAudioDG to reenable APO signature checking.
3. Unregister the APO by opening a command shell with Administrator privileges in the build directory (e.g. x64\Debug) and typing regsvr32 /u FiltergAPO.dll