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WINMM sends the MODM_GETVOLUME message to the modMessage function of a MIDI output driver to request the current volume level setting for a MIDI device.
Syntax
DWORD modMessage(
UINT uDeviceID,
UINT uMsg,
DWORD_PTR dwUser,
DWORD_PTR dwParam1,
DWORD_PTR dwParam2
);
Parameters
uDeviceID
Specifies the ID of the target device. Device IDs are sequential and have an initial value of zero and a final value that is equal to one less than the number of devices that the driver supports.uMsg
WINMM sets this parameter to MODM_GETVOLUME when it calls modMessage to process this message.dwUser
Use this parameter to return instance data to the driver. Drivers that support multiple clients can use this instance data to track the client that is associated with the message.dwParam1
This parameter specifies a far pointer to a DWORD location. The driver fills this location with the current volume level setting. The high-order word contains the right channel setting and the low-order word contains the left channel setting. A value of zero is silence, and a value of 0xFFFF is full volume. If the driver does not support both left and right channel volume changes, it returns the volume level setting in the low-order word.dwParam2
Not used.
Return value
The modMessage message returns MMSYSERR_NOERROR, if the operation is successful. Otherwise, it returns one of the error messages in the following table.
| Return code | Description |
|---|---|
| MMSYSERR_NOTENABLED | The driver failed to load or initialize. |
| MMSYSERR_NOTSUPPORTED | The driver does not support changes to volume level settings. |
Remarks
Only drivers for internal synthesizer devices can support volume level changes. Drivers for MIDI output ports should return an MMSYSERR_NOTSUPPORTED error for this message. Support for volume level changes by internal synthesizer devices is optional. However, if a driver supports changes to the volume level with the MODM_SETVOLUME message, it must support queries with the MODM_GETVOLUME message.
Requirements
Target platform |
Desktop |
Version |
Available in Windows XP and later Windows operating systems. |
Header |
Mmddk.h (include Mmddk.h, Mmsystem.h, or Windows.h) |