MIDI authors should be aware of several design concerns when producing a MIDI song:

• The General MIDI specification defines a base-level configuration and an extended-level configuration for synthesizers. Because you cannot control which synthesizer is used to play your song, you should provide percussion and melody tracks for both configurations. The table in the Channel Assignments section shows you which channels to allocate.

• Put your important melody sounds in the lower-numbered channels. By prioritizing channel use, you ensure that your song sounds reasonable when it is played on hardware that supports only a few channels.

• When selecting instruments for your MIDI song, use the instruments that are defined for the most popular MIDI devices. Your song can then be easily and accurately mapped to other hardware formats.

• When using nonpercussive channels, limit the polyphony (number of simultaneous notes) to 6 notes for the base level and 16 notes for the extended level.

• When using percussion channels, limit the polyphony to 3 notes for the base level and 16 notes for the extended level.

• Use the standard General MIDI patch assignments and percussion key assignments shown in the table in the Patch Assignments section and the figure in the Percussion Key Assignments section.

• Always send a program change command to a channel before sending other commands to the channel. For channels 10 and 16, which are used for percussion, select patch 0.

• Always send a MIDI main volume controller command (controller number 7) to a channel after selecting a patch by sending a program change command. Use the value of 80 (X'50') for normal listening levels.