MODM_GETVOLUME

The MODM_GETVOLUME message requests a MIDI output driver to return the current volume level setting for the specified device.

Parameters

uDeviceId

Device identifier (0, 1, 2, and so on) for the target device.

uMsg

MODM_GETVOLUME

dwUser

Device instance identifier.

dwParam1

Pointer to a DWORD location to receive the volume setting.

dwParam2

Not used.

Return Value

The driver should return MMSYSERR_NOERROR if the operation succeeds. Otherwise it should return one of the MMSYSERR or MIDIERR error codes defined in mmsystem.h. See midiOutGetVolume return values in the Win32 SDK.

Comments

A client sends the MODM_GETVOLUME message by calling the user-mode driver’s modMessage entry point, passing the specified parameters.

Support for this message by user-mode drivers is optional. If the driver supports MODM_SETVOLUME, it must support MODM_GETVOLUME.

The volume value is returned in the DWORD pointed to by dwParam1 as follows:

Channel	Portion of dwParam1 Used
Left channel	Low word
Right channel	High word
Single channel	Low word

A value of zero is silence, and a value of 0xFFFF is full volume.

Typically, the user-mode driver calls DeviceIoControl to send the kernel-mode driver an IOCTL_MIDI_GET_VOLUME control code.

Only drivers for internal synthesizer devices can support volume level changes. Drivers for MIDI output ports should return a MMSYSERR_NOTSUPPORTED error for this message.