Process 5.1 audio in DSP plugin in Win7

[KimT]

Hi,
I have a WMP audio DSP plugin which does binaural downmixing from 5.1/7.1 to
2.0. In the plugin I use "SetSpeakerConfig" from dsound SDK to set the active
speaker configuration in Xindows XP to 7.1. The reason I have to do this is
that Windows XP/Vista/7 automatically downmixes the audio data BEFORE it
reaches the DSP plugin.
In other words: If the Windows speaker configuration is set to stereo my
plugin does not work correctly as it will only receive stereo audio data even
if I playback a 5.1 multichannel audio (or video) file in WMP.

"SetSpeakerConfig" worked fine in Windows XP but in Windows Vista/7 it has
not effect. How do you make WMP and Win Vista/7 stop downmixing the audio
before it reaches the DSP plugin?

It is not acceptable that you need to have a 7.1 sound card and set the
Windows speaker configuration in control panel to 7.1 just to make WMP
deliver the real multichannel data. I need a lasting solution where I am sure
always to get the number of audio channels available in the audio material. I
think the plugin from DFX somehow handles this problem.

Best regards,
Kim Therkelsen