Windows Media Player and audio engine behavior

Question

I have made one LFX and one GFX module both residing in the same dll.
I have noticed some strange behavior with windows media player which I don't understand.
When playing back audio with WMP there are always two processes (image names) that loads my dll with APOs. One process called audiodg.exe and one called svchost.exe. My understanding is that my APOs would be loaded only by the audio engine which I belief
is found in audiodg.exe.
Is there any explanation of why WMP causes my APO dll to be loaded by two different modules (image names) at the same time?
One of the reasons I'm asking is that I have problems getting my APOs working correctly with the tidal web player (tidal.com). I'm not sure what the problem is but I can see that my APO dll is loaded by two different modules (image names) at the same time,
just like WMP.
Thomas BE

Answer 1

The "Windows Audio service" svchost.exe process is always running; you can check its current state via the "sc query audiosrv" command.
>sc query audiosrv
SERVICE_NAME: audiosrv
        TYPE               : 20  WIN32_SHARE_PROCESS
        STATE              : 4  RUNNING
                                (STOPPABLE, NOT_PAUSABLE, IGNORES_SHUTDOWN)
        WIN32_EXIT_CODE    : 0  (0x0)
        SERVICE_EXIT_CODE  : 0  (0x0)
        CHECKPOINT         : 0x0
        WAIT_HINT          : 0x0
When someone calls IAudioClient::IsFormatSupported(...), your SFX is loaded into audiosrv to answer the query. Some media players call this, and some don't.
When audio actually plays, audiosrv launches audiodg.exe. audiodg.exe builds the full audio pipeline from app to driver, including all of your APOs.
Some time after audio stops playing, audiodg.exe shuts itself down.
Matthew van Eerde