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The following webpage http://www-etud.iro.umontreal.ca/~boulanni/icml2012 mentions that it is possible to convert MIDI files to piano rolls in python:

Below are the source files (MIDI) for the 4 datasets evaluated in the paper (split in train, validation and test sets). You can generate piano-rolls from the source files by transposing each sequence in C major or C minor and sampling frames every eighth note (quarter note for JSB chorales) following the beat information present in the MIDI file. Alternatively, pickled piano-rolls for use with the Python language are also provided.

They have done it for a few examples. I would like to know how to do it but I cannot find in their code-base anywhere where it is done. Is there a simple way to do this?

So I know from How to convert midi files to keypresses (in Python)? that I can do

import midi
midi.read_midifile('example.mid')

that will return me a pattern of the likes of 

midi.Pattern(format=1, resolution=220, tracks=\
[midi.Track(\
  [midi.NoteOnEvent(tick=0, channel=0, data=[43, 20]),
   midi.NoteOffEvent(tick=100, channel=0, data=[43, 0]),
   midi.EndOfTrackEvent(tick=1, data=[])])])

But then how do I transpose the sequence in C major or minor and how do I sample frames every eighth note?

So it seams that in the code referenced above, they do:

from midi.utils import midiread, midiwrite
midiread(midi_file, (21, 109), 0.3).piano_roll

So then my question becomes, where do I find those midi.utils and how do I assure that the sequence is transposed in the right key and sampled at the right rate?

Matthieu Brucher
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patapouf_ai
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1 Answers1

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So it seems that they have a modified version of the original midi library (https://github.com/vishnubob/python-midi) which creates piano rolls. And the modified version of the code can be found here: http://www.iro.umontreal.ca/~lisa/deep/midi.zip .

patapouf_ai
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