I would like to know is there any way I create an application which can intercept all the audio that is being played back on the computer, so I can process the audio (apply some effect) and then pass it further to the Windows audio subsystem?
I just had a glimpse in Vista/7 WASAPI, there is this sAPO: http://www.microsoft.com/whdc/device/audio/sysfx.mspx but it seems that I cannot create my sAPO and install it anywhere I like - I need a WHQL drivers for this.
Is there any universal way to do that? I have an experience with DirectSound but I haven't seen any useful info about intercepting the audio streams.
If you're loading a custom sAPO, you're globally affecting the sound for a system. This is going to require signing. From this article:
The audio engine does not load unsigned sAPOs into the audio processing graph. So while you are testing your sAPO, you must disable the protected process for Audiodg.exe. To disable the protected process, set the value of the DisableProtectedAudioDG registry key to '1'.
来源：https://stackoverflow.com/questions/4512097/intercepting-and-postprocessing-all-audio-streams-on-windows