MIDI-129: Try to remove PrettyMIDI dependency

[SamuelJanas]

MIDI-129

Getting rid of the dependency on PrettyMIDI so that we could have a little more freedom when it comes to future development.

[roszcz]

Looks good! Can you add some tests for this? :)

[SamuelJanas]

I've written some baseline tests to see if everything is of the correct type/exists.

The code is now a bit of a mess, I'll move classes that work as containers to a separate file. The new change also made it possible to cut some lines of code in different places. Some additional changes need to be made. to_midi() will probably work with MidiFile now. I'll have to add some changes so that rendering would work without PrettyMIDI.

I'm trying to figure out what's the minimal amount of code I can copy from PrettyMIDI for our functionality to still work properly - without the dependency. We'll need to credit them in the docs for sure though!

[SamuelJanas]

    def to_midi_midi_file(self, instrument_name: str = "Acoustic Grand Piano"):
        track = MidiFile()
        program = pretty_midi.instrument_name_to_program(instrument_name)
        instrument = midi_containers.Instrument(program=program, name=instrument_name)

        note_data = self.df[["velocity", "pitch", "start", "end"]].to_records(index=False)

        for velocity, pitch, start, end in note_data:
            note = midi_containers.Note(velocity=int(velocity), pitch=int(pitch), start=start, end=end)
            instrument.notes.append(note)

        track.instruments.append(instrument)

        return track

instrument_name_to_program is I think one of the last dependencies, it's a matter of creating a list that matches general MIDI convention We probably want to keep this functionality as it allows for creating Cello mp3 as simply as specifying instrument_name = "cello".
I've tested loading the file in -> extracting MidiPiece from it -> calling the new to_midi -> loading it in -> exporting to wav
And it works as expected. There's still some experimenting to do.

[roszcz]

    def to_midi_midi_file(self, instrument_name: str = "Acoustic Grand Piano"):
        track = MidiFile()
        program = pretty_midi.instrument_name_to_program(instrument_name)
        instrument = midi_containers.Instrument(program=program, name=instrument_name)

        note_data = self.df[["velocity", "pitch", "start", "end"]].to_records(index=False)

        for velocity, pitch, start, end in note_data:
            note = midi_containers.Note(velocity=int(velocity), pitch=int(pitch), start=start, end=end)
            instrument.notes.append(note)

        track.instruments.append(instrument)

        return track

instrument_name_to_program is I think one of the last dependencies, it's a matter of creating a list that matches general MIDI convention We probably want to keep this functionality as it allows for creating Cello mp3 as simply as specifying instrument_name = "cello". I've tested loading the file in -> extracting MidiPiece from it -> calling the new to_midi -> loading it in -> exporting to wav And it works as expected. There's still some experimenting to do.

Maybe we could ignore the instrument/program problem, and just assume everything is a piano? As far as I know modern Digital Audio Workstation software don't really use this property, and manage different instruments independently from the MIDI file.