function sets the volume of a MIDI output device.
| HMIDIOUT hmo,
| DWORD dwVolume
Handle of an open MIDI output device. This parameter can also contain the
handle of a MIDI stream, as long as it is cast to HMIDIOUT
. This parameter can also be a device identifier.
New volume setting. The low-order word contains the left-channel volume
setting, and the high-order word contains the right-channel setting. A value of
0xFFFF represents full volume, and a value of 0x0000 is silence.
If a device does not support both left and right volume control, the low-order
word of dwVolume
specifies the mono volume level, and the high-order word is ignored.
Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error
values include the following:
||The specified device handle is invalid.
||The system is unable to allocate or lock memory.
||The function is not supported.
If a device identifier is used, then the result of the midiOutSetVolume
call applies to all instances of the device. If a device handle is used, then
the result applies only to the instance of the device referenced by the device
Not all devices support volume changes. You can determine whether a device
supports it by querying the device using the midiOutGetDevCaps
function and the MIDICAPS_VOLUME flag.
You can also determine whether the device supports volume control on both the
left and right channels by querying the device using the midiOutGetDevCaps
function and the MIDICAPS_LRVOLUME flag.
Devices that do not support a full 16 bits of volume-level control use the
high-order bits of the requested volume setting. For example, a device that
supports 4 bits of volume control produces the same volume setting for the following
volume-level values: 0x4000, 0x43be, and 0x4fff. The midiOutGetVolume
function returns the full 16-bit value, as set by midiOutSetVolume
, irrespective of the device's capabilities.
Volume settings are interpreted logarithmically. This means that the perceived
increase in volume is the same when increasing the volume level from 0x5000 to
0x6000 as it is from 0x4000 to 0x5000.
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