This function sends messages from user applications to the audio driver's PDD layer.
DWORD PDD_AudioMessage( UINT uMsg, DWORD dwParam1,
DWORD dwParam2 );
Dependent on uMsg.
Custom functions can be accessed through this function. It is ultimately called in response to the waveOutMessage and waveInMessage functions.
This function is declared in the Waveddsi.h header file.