Sent to a MIDI output device driver to set the volume for a device.
MMSYSERR_NOTENABLED | The driver failed to load or initialize. |
MMSYSERR_NOTSUPPORTED | The driver does not support changes to volume level. |
This volume message is not the same as the MIDI volume controller message which will be used by sequencers and the mapper. This volume is the final output volume on the card; therefore, 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. Support for volume level changes is optional for internal synthesizer devices. When a driver receives a MODM_GETDEVCAPS message, it should indicate support for volume level changes by setting or clearing the MIDICAPS_VOLUME and MIDICAPS_LRVOLUME bits in the dwSupport field of the MIDIOUTCAPS data structure. If a driver supports the MODM_SETVOLUME message, then it must also support MODM_GETVOLUME.
MODM_GETVOLUME