When/how is an application added to the Windows 7 Volume Mixer window?

I'm trying to get an application which ran okay on XP to run properly on Windows 7 (this is not something I wrote - I'm helping a friend.)

It was able to play audio on XP but cannot on Windows 7 - nothing is heard. Have exhausted a search and check of all settings in Windows 7 as regards audio (have spent many hours searching and reading.)

There is no entry in the Windows 7 Volume Mixer for the application at any time while it is running.

By playing with some other applications I've found that it seems that an application is not added to the Mixer until it actually creates a sound but I've found at least one program which is added to the Mixer right when the program starts and before it has played any sounds.

Is there an API which allows an application to "register" itself with the Windows 7 Volume Mixer so that an entry for it appears in the Mixer even though it has not yet produced any开发者_开发技巧 sounds?

According to this blog post, the audio subsystem keeps track of PIDs that play audio and the volume mixer is able to access this list. It is possible to change the name displayed in SndVol with IAudioSessionControl, so maybe that alone is enough for it to be "registered"

An app slider is added to the mixer when an audio session is created. There are two things that can cause an audio session to be created: First off, when an audio stream created by the app transitions to the "start" state. The other case is when an application manipulates the audio volume using the IAudioSessionControl interface.