The WIDM_LOWPRIORITY message requests a waveform input driver to run at low priority.
Parameters
uDeviceId
Device identifier (0, 1, 2, and so on) for the target device.
uMsg
WIDM_LOWPRIORITY
dwUser
Device instance identifier.
dwParam1
Not used.
dwParam2
Not used.
Return Value
The driver should return MMSYSERR_NOERROR if the operation succeeds. Otherwise it should return one of the MMSYSERR or WAVERR error codes defined in mmsystem.h.
Comments
A client sends the WIDM_LOWPRIORITY message by calling the user-mode driver's widMessage entry point, passing the specified parameters.
Typically, the user-mode driver calls DeviceIoControl to send the kernel-mode driver an IOCTL_WAVE_SET_LOW_PRIORITY control code. Kernel-mode drivers using soundlib.lib allow only one client to be running at low priority.
Support for this message by user-mode drivers is optional.