music21: writing notes to MIDI file by note position

Question

I am using music21 to write midi file from the note values.

Following code writes three notes sequentially.

However, how do I insert an "empty" space between the notes?

It would be very easy if I could just insert the notes by their "position" so that I wouldn't have to calculate the position/length of each silent interval. Is that possible with music21?

import music21
from music21 import *

mt = midi.MidiTrack(1)
mt2 = midi.MidiTrack(1)

# duration, pitch, velocity
data = [[1024, 60, 90], [1024, 50, 70], [1024, 51, 120],[1024, 62, 80], ]

t=0
tLast=0
for d,p,v in data:
    dt = midi.DeltaTime(mt)
    dt.time = t-tLast
    #add to track events
    mt.events.append(dt)

    me=midi.MidiEvent(mt)
    me.type="NOTE_ON"
    me.channel=1
    me.time= None #d
    me.pitch = p
    me.velocity = v
    mt.events.append(me)

    # add note off / velocity zero message
    dt = midi.DeltaTime(mt)
    dt.time = d
    # add to track events
    mt.events.append(dt)

    me=midi.MidiEvent(mt)
    me.type="NOTE_ON"
    me.channel=1
    me.time= None #d
    me.pitch = p
    me.velocity = 0
    mt.events.append(me)
    tLast = t+d
    t +=d

dt=midi.DeltaTime(mt)
dt.time = 0
mt.events.append(dt)
me = midi.MidiEvent(mt)
me.type = "END_OF_TRACK"
me.channel = 1
me.data =''  # must set data to empty string
mt.events.append(me)

mf = midi.MidiFile()
mf.ticksPerQuarterNote = 1024 # cannot use: 10080
mf.tracks.append(mt)

mf.tracks.append(mt2)


mf.open('test.mid', 'wb')
mf.write()
mf.close()

Answer 1

In a MIDI file, all events are preceded by a delta time value that specifies how long to wait from the last event.

In your code, t and tLast are both increased by the note's duration, so there is no pause between a note off and the following note on.

If you want the next note to start later, you have to increase t by a larger amount.