Patch
Maps
Each channel
map entry can have an associated patch map. Patch maps affect MIDI
program-change and volume-controller messages. Program-change messages tell a
synthesizer to change the instrument sound (patch) for a specified channel.
Volume-controller messages set the volume for a channel.
A patch map
has a translation table with an entry for each of the 128 program-change
values. Each patch map specifies the following:
A destination program-change
value
A volume scalar
An optional key map
When
program-change messages are received by the MIDI Mapper, the destination
program-change value is substituted for the program-change value in the
message. For example, if the destination program-change value for
program-change 16 is 18, the MIDI Mapper modifies the MIDI program-change
message as shown in the following illustration.
{bml bm79.WMF}