python 解析 MIDI 文件并生成 MIDI 文件

import mido
import sys
import json
def midifile_to_dict(mid):
    tracks = []
    for track in mid.tracks:
        tracks.append([vars(msg).copy() for msg in track])
    return {
        'ticks_per_beat': mid.ticks_per_beat,
        'tracks': tracks,
    }
mid = mido.MidiFile("Pianoboy-你离开的事实_爱给网_aigei_com.mid", clip=True)
dict_mid = midifile_to_dict(mid)
json_mid = json.dumps(dict_mid, indent=2)
print(json_mid)
track0 = (dict_mid["tracks"])[0]
track1 = (dict_mid["tracks"])[1]
track2 = (dict_mid["tracks"])[2]
######### EXTRACT MUSIC DATA FROM THE TWO MAIN TRACKS ##########
on_off1=[]
note1_on=[]
note1_off=[]
velocity1_on=[]
velocity1_off=[]
time1_on=[]
time1_off=[]
on_off2=[]
note2_on=[]
note2_off=[]
velocity2_on=[]
velocity2_off=[]
time2_on=[]
time2_off=[]
for i, msg in enumerate(track1):
    if msg["type"] is "note_on":
        on_off1.append(1)
        note1_on.append(msg["note"])
        velocity1_on.append(msg["velocity"])
        time1_on.append(msg["time"])
    if msg["type"] is "note_off":
        on_off1.append(0)
        note1_off.append(msg["note"])
        velocity1_off.append(msg["velocity"])
        time1_off.append(msg["time"])
for i, msg in enumerate(track2):
    if msg["type"] is "note_on":
        on_off2.append(1)
        note2_on.append(msg["note"])
        velocity2_on.append(msg["velocity"])
        time2_on.append(msg["time"])
    if msg["type"] is "note_off":
        on_off2.append(0)
        note2_off.append(msg["note"])
        velocity2_off.append(msg["velocity"])
        time2_off.append(msg["time"])
######### CREATE NEW MIDI FILE ############
outfile = mido.MidiFile()
outtrack0 = mid.tracks[0]
outtrack1 = mido.MidiTrack()
outtrack2 = mido.MidiTrack()
outfile.tracks.append(outtrack0)
outfile.tracks.append(outtrack1)
outfile.tracks.append(outtrack2)
for i in range(len(on_off1)):
    if on_off1[i]:
        outtrack1.append(mido.Message('note_on', note=note1_on.pop(0), velocity=velocity1_on.pop(0), time=time1_on.pop(0)))
    else:
        outtrack1.append(mido.Message('note_off', note=note1_off.pop(0), velocity=velocity1_off.pop(0), time=time1_off.pop(0)))
for i in range(len(on_off2)):
    if on_off2[i]:
        outtrack2.append(mido.Message('note_on', note=note2_on.pop(0), velocity=velocity2_on.pop(0), time=time2_on.pop(0)))
    else:
        outtrack2.append(mido.Message('note_off', note=note2_off.pop(0), velocity=velocity2_off.pop(0), time=time2_off.pop(0)))
outfile.save('createtest.mid')