Once you open a MIDI output device, you can begin sending it MIDI messages using the following functions:
| Function | Description |
| midiOutLongMsg | Sends a buffer of MIDI data to the specified MIDI output device. Use this function to send multiple MIDI events, including system exclusive messages, to a MIDI device. |
| midiOutShortMsg | Sends a MIDI message to a specified MIDI output device. |
| midiOutReset | Turns off all notes on all channels for a specified MIDI output device. Any pending system-exclusive buffers are marked as done and returned to the application. |
Use midiOutShortMsg to send any MIDI message (except for system-exclusive messages). This function takes an HMIDIOUT parameter specifying the MIDI output device to send the message to, and a DWORD for the MIDI message. The message is packed into the DWORD, as shown in the following illustration:
This illustration is not available for this release
The two MIDI data bytes are optional, depending on the MIDI status byte. The following code fragment uses midiOutShortMsg to send a given MIDI event to a given MIDI output device:
/* Sends a given MIDI event to the given output device
*/
UINT sendMIDIEvent(hMidiOut, bStatus, bData1, bData2)
HMIDIOUT hMidiOut; // handle to the output device
BYTE bStatus; // MIDI status byte
BYTE bData1; // first MIDI data byte
BYTE bData2; // second MIDI data byte
{
union {
DWORD dwData;
BYTE bData[4];
} u;
/* Construct the MIDI message */
u.bData[0] = bStatus;
u.bData[1] = bData1;
u.bData[2] = bData2;
u.bData[3] = 0;
/* Send the message */
return midiOutShortMsg(hMidiOut, u.dwData);
}
Note:
MIDI output drivers are not required to verify data before sending it to an output port. It is up to applications to ensure only valid data is sent using midiOutShortMsg.