How to change instrument?

[aquiire]

Could you please give an example with two or more instruments? https://github.com/MarkCWirt/MIDIUtil/issues/1 This is unclear to me..

[MarkCWirt]

This is done with the program change. As an example, the following snippet creates two tracks, assigns program 0 to channel 0 and program 6 to channel 1. Then it adds two notes to the separate track and channel.

If you listed to the MIDI file with a player that maps pograms to General MIDI, you will hear the first note as a piano, and the second as a harpsicord.

from midiutil import MIDIFile

# Create a two-track file
MyMIDI = MIDIFile(2, adjust_origin=False)
MyMIDI.addTempo(0, 0, 30)

MyMIDI.addProgramChange(0, 0, 0, 0)
MyMIDI.addProgramChange(0, 1, 0, 6)


track = 0
time = 0
channel = 0
pitch = 60
duration = 1
volume = 100

MyMIDI.addNote(track, channel, pitch, time, duration, volume)

track = 1
time = 1
channel = 1
MyMIDI.addNote(track, channel, pitch, time, duration, volume)

with open("output.mid", 'wb') as binfile:
    MyMIDI.writeFile(binfile)

Note that the library uses a zero-origin for program, whereas most documentation is one-origined!