Music21 merge midi/merge instruments

Question

I'm currently working on a project that has some midi processing. For my processing I needed to separate percussive instruments from pitched ones. After I did my processing (transposing the pitched instruments to another key) I need to merge the two back together.

My drums and pitched instruments are saved as midi files. My code is:

    pitch_midi = music21.converter.parse(pitch)
    drums_midi = music21.converter.parse(drums)
    transposed_pitch = pitch_midi.transpose(semitones)  # Int Variable
    transposed_pitch.append(drums_midi)
    transposed_pitch.write('midi', 'Transposed.mid')

The code runs just fine but the saved midi file doesn't include the drum tracks. The type of drums_midi is "<class 'music21.stream.base.Score'> " and the type of the transposed_pitch is "<music21.stream.Score 0x155ad892af0> " and I suspect that this is the problem.

If I do

transposed_midi = transposed_pitch.append(drums_midi)

I get an AttributeError: 'NoneType' object has no attribute 'write'. Which is makes sense since the type of transposed_midi is NoneType.

Any ideas how to overcome that?

As @Jacob Walls notes below -- your code works in newest music21 — Michael Scott Asato Cuthbert, Sep 09 '22 at 08:03

score 1 · Answer 1 · answered May 21 '22 at 12:46

1

music21 currently lacks support for exporting percussion tracks to MIDI, see https://github.com/cuthbertLab/music21/issues/238.

answered May 21 '22 at 12:46

Jacob Walls

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Thanks for the reply. I ended up using pretty_midi for that after all. – Eva K. May 22 '22 at 13:59
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I just went and implemented it in music21, so you should be able to install the bleeding-edge dev version and give it a spin! – Jacob Walls May 23 '22 at 01:51

Music21 merge midi/merge instruments

1 Answers1