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I have extracted notes, chords, rests and time signatures from parsed MIDI file. Storing them and again playing them back, I still cannot get the original speed and mix of sounds. What am I doing wrong? What am I forgetting?

temp_name = 'Chopin.midi'#any example of MIDI song
temp_score = converter.parse(temp_name)
flat = temp_score.flat
all_elements = []
# Iterate over the elements in the flattened stream
for el in flat:
    if isinstance(el, music21.note.Note):
        pitch = el.pitch
        note_name = pitch.nameWithOctave
        new_note_c = note.Note(note_name)
        new_note_c.duration = el.duration
        dur = float(el.duration.quarterLength)
        all_elements.append((str(note_name), dur))
    elif isinstance(el, music21.chord.Chord):
        chord_pitches = []
        for p in el.pitches:
            #note_name = p.pitch
            #note_name_oct = note_name.nameWithOctave
            new_note_c = note.Note(p.nameWithOctave)
            #new_note_c.duration = el.duration
            dur = float(el.duration.quarterLength)
            chord_pitches.append((str(new_note_c.nameWithOctave)))
        chord_pitches = ".".join([i for i in chord_pitches])
        all_elements.append((chord_pitches,dur))
    
    
    #elif isinstance(el, note.Rest):
    #    rest_duration = el.duration.quarterLength
    #    temp_str = 'REST'
    #    all_elements.append((temp_str, rest_duration))
    
    
    elif isinstance(el, music21.meter.TimeSignature):
        current_time_signature = el.ratioString
        all_elements.append(('TIME_SIGNATURE', current_time_signature))

Here, extracting the rests resulted in unnecessary rests in the output and I have no idea how it is possible. The code to run back these sequences is as follows:

def get_music_midi_filename_from_chords(input_chords, initial_ts, initial_tempo):
    midi_stream = stream.Stream()
    i=0
    new_tempo = tempo.MetronomeMark(number=initial_tempo)
            
    midi_stream.append(new_tempo)
    midi_stream.append(initial_ts)
    
    for note_pattern, duration_pattern in input_chords:
        if 'TIME_SIGNATURE' in note_pattern:
            ts_numerator, ts_denominator = duration_pattern.split('/')
            new_ts = meter.TimeSignature(f'{ts_numerator}/{ts_denominator}')
            midi_stream.append(new_ts)

        if '.' in note_pattern:
            notes_in_chord = note_pattern.split('.')
            chord_notes = []
            for current_note in notes_in_chord:
                new_note = note.Note(current_note)
                new_note.duration = duration.Duration(duration_pattern)
                new_note.storedInstrument = instrument.Piano()
                chord_notes.append(new_note)
            new_chord = chord.Chord(chord_notes)
            midi_stream.append(new_chord)
        
        elif 'REST' in note_pattern:
            rest_ = note.Rest()
            rest_.duration = duration.Duration(duration_pattern)
            midi_stream.append(rest_)
        else:
            if is_valid_pitch(note_pattern):
                note_single = note.Note(note_pattern)
                note_single.duration = duration.Duration(duration_pattern)
                note_single.storedInstrument = instrument.Piano()
                midi_stream.append(note_single)

    midi_stream = midi_stream.chordify()
    timestr = time.strftime("%Y%m%d-%H%M%S")
    new_file = 'output-' + timestr + '.mid'
    return midi_stream.write('midi', fp=new_file
)

Here, initial tempo is taken as initial_tempo = temp_score.flat.getElementsByClass('MetronomeMark')[0].number and initial time signature is taken as initial_ts = temp_score.recurse().getElementsByClass(music21.meter.TimeSignature)[0]

The function is_valid_pitch() is :

def is_valid_pitch(note_pattern):
    try:
        p = music21.pitch.Pitch(note_pattern)
        return True
    except:
        return False

I am addressing time signatures and tempo as well from the song. But again, the timing duration is differed from the original. When I include the rests from the MIDI flat, why am I getting unusual lengths of rests and the duration is increased way too much? How can I improve this code? What am I missing? I am quite lost in it now.

I need to be able to store all the required features under an array, basically trying to create an audio dataset, and then after training, I will be producing the music. But before training, I am not able to even replay back the same MIDI I have parsed in the original way.

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  • 1
    Can you combine your code into a single example that will run by itself? It takes some work to combine your various code snippets to test your code. Also, right now, your example code is missing a function "is_valid_pitch" that it needs to run.
    – Bavi_H
    Feb 14, 2023 at 16:55
  • 1
    Can you provide a simple MIDI file you are having a problem with?
    – Bavi_H
    Feb 14, 2023 at 16:55
  • 1
    Just out of curiosity, can you tell more about what kind of MIDI file analysis or conversion you eventually want to accomplish?
    – Bavi_H
    Feb 14, 2023 at 17:26
  • I answered some of you r queries and added the code snippets in my question as well. I want to just play back the original MIDI back by taking the features. After that, I may be able to train.
    – ROOT31415
    Feb 15, 2023 at 7:44

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