| Microsoft DirectX 9.0 SDK Update (October 2004) |
A channel message is addressed to a particular MIDI channel, which corresponds to a part in the music.
A channel message can be either a mode message or a voice message.
A mode message specifies how the channel is to respond to subsequent voice messages. For example, a mode message might instruct the channel to remain silent, ignoring all note-on messages.
A voice message instructs the channel to begin or stop playing a note or to modify notes in some way. Most channel messages are voice messages.
The following table describes types of voice messages.
| Voice message | Command |
| Note-on | Play a note. |
| Note-off | Stop playing the note. |
| Control change | Modify the tone with data from a pedal, lever, or other device; also used for miscellaneous controls such as volume and bank select. |
| Program (patch) change | Select an instrument for the channel by assigning a patch number. |
| Aftertouch | Modify an individual note, or all notes on the channel, according to the aftertouch of a key. |
| Pitch bend change | Modify the pitch of all notes played on the channel. |
Keep in mind that these descriptions apply to standard MIDI messages, not MIDI data that has been converted to performance message format. For example, two MIDI messages to start and stop a note are combined by DirectMusic into a single performance message that specifies the duration of the note. Performance messages also contain additional information about timing and routing.
The following topics contain more information about MIDI channel messages and how they are implemented in DirectMusic: