Jupyter notebook midi player doesn't recognize MetronomeMark

[oxygen-dioxide]

music21 version

9.7.0

Operating System(s) checked
Windows 11

Problem summary
In Jupyter Notebook, load a midi file with 6/8 timesignature, play it with .show('midi'). It will play faster than playing the original midi file in windows media player.

If I .show('musicxml') in normal python command line and play it in the musescore window poped up, or .show('.midi') in normal command line, the playing speed is correct

Steps to reproduce
只要平凡68.zip

run in both Jupyter Notebook and normal python command line.

import music21
a=music21.converter.parseFile(r"C:\Users\lin\Desktop\只要平凡68.mid")
a.show('midi')
a,show('musicxml')

Expected vs. actual behavior
Expected: no matter how I play it, it plays in the same speed.
Actual: If I play it with .show('midi') in jupyter notebook, it will play faster.

More information

[mscuthbert]

Oh, in this case the bug is in music21j.

Music21j is used for playing MIDI files in the browser. Can you see if the problem persists even in a very simple file you create on your own (like converter.parse('tinynotation: 6/8 c8 d e f d e c2.') ).

It's either in music21j or midicube -- both though are projects I maintain.

[oxygen-dioxide]

This minimal example plays without problem. It plays in Jupyter Notebook .show('midi'), in command line .show('midi'), and in musescore all with the same speed

[mscuthbert]

hmmm... let's try to trim down your example until it plays at the proper speed -- can you reduce it to a single part and just a few notes and have it have the problem?

When there are problems with "when I import file X and export it as Y it breaks" usually the problem is either "importing file X has a bug". or "export anything as Y has a problem". - very rare that the problem is the entire import to export chain, so I'd like to figure out where the bug is to fix it.

My guess is that it's in export (hence the test above) since music21j has never had the amount of testing that music21(python) has, mostly because it's never had the amount of $$ support that m21-python has. :-)

[oxygen-dioxide]

However, if I insert a custom MetronomeMark to it, Jupyter Notebook still plays at the original speed, but command line .show('midi') and musescore play at new speed.
It seems that Jupyter Notebook player completely ignores the MetronomeMark.

import music21
a=music21.converter.parse('tinynotation: 6/8 c8 d e f d e c2.')
m=music21.tempo.MetronomeMark(number=40)
a.measure(1).insert(0, m)
a.show('midi')

[mscuthbert]

Is it the same in 4/4 etc.?

I know that there was a problem (I think well documented in music21j) where in the past the two systems used different tempo systems. Music21j in the past just used Stream.tempo = bpm --- it only got the full tempo.MetronomeMark system later.

Basically MIDI in Juptyer notebook is limited to what music21j supports -- and that's about 1/10th of what music21 supports. For that reason, music21j is still a beta project -- lack of support of just about everything is well known there.

Music21p wants to represent the full Midi 1.0 + 1.1 specs -- so problems there are definitely worth reporting. Music21j would like to get there, but there's no time or money. And no one in academia cared about music21j so it wasn't even useful for promotions in academia (when I worked there!)

[oxygen-dioxide]

Oh yes it's the same in 4/4. Sorry for misleading you when I initially found this issue

[oxygen-dioxide]

Currently I'll just bypass it and play the midi in windows media player with music21.converter.subConverters.ConverterMidi().show(a, 'mid')