Music 21 finds notes with duration 1/3 when there are none

Question

I wrote a python script to extract all the notes, their offset, and durations from a midi file. I have achieved this, but I have a problem with the quarterlengths (the duration in quarter notes). I get many notes with duration 1/3, or some other multiple of a third. However, as far as I can tell, none of the notes have any duration of 1/3, because they are all quarter notes, half notes, or sixteenth notes. Where are these durations coming from?

I've tried using pieces with different times signatures, but both 4/4 pieces, 3/4 pieces, and 3/2 pieces come up with 1/3 quarter lengths for some of the notes. Here is my code for reference:

lis = []
s = converter.parse("music2/" + "bwv525-1.mid")
a = s.flat
for item in a.notes:
    print(item.duration.type, item.duration.dots, item.quarterLength)

where bwv525-1.mid is the file I am reading

Here's part of the output: eighth 0 0.5 eighth 0 1/3 eighth 0 1/3 16th 0 0.25 quarter 0 1.0 eighth 0 1/3 eighth 0 1/3 eighth 0 1/3 eighth 0 1/3 16th 0 0.25 16th 0 0.25 16th 0 0.25 16th 0 0.25 16th 0 0.25 — Pseudo Nym, Jan 12 '19 at 19:49
Maybe this helps: http://web.mit.edu/music21/doc/moduleReference/moduleDuration.html — moritzg, Jan 12 '19 at 20:00

score 3 · Accepted Answer · answered Jan 13 '19 at 01:37

3

I know this piece well and this encoding: most of its notes are encoded as 1/3 length eighth notes and 1/6 length sixteenth rests to give them some separation.

MIDI files generally encode performance not scores.

answered Jan 13 '19 at 01:37

Michael Scott Asato Cuthbert

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is there a way to know which notes are being shortened and which ones are normal length? Essentially, is there a way to correctly represent them? – Pseudo Nym Jan 13 '19 at 01:51
Not w/ MIDI -- it's the reason why MusicXML and other formats were invented. – Michael Scott Asato Cuthbert Jan 13 '19 at 06:00

Music 21 finds notes with duration 1/3 when there are none

1 Answers1