Remove all notes example from the README not working

[Phibonacci]

I am looking to remove all the notes from each chords but the first one, for each track. To get started I tried the following example from the README that is supposed to remove absolutely all notes from the midi.

using Melanchall.DryWetMidi.Core;
using Melanchall.DryWetMidi.Interaction;

var midiFile = MidiFile.Read("myfile.mid");
foreach (var trackChunk in midiFile.GetTrackChunks())
{
    using (var notesManager = trackChunk.ManageNotes())
    {
        notesManager.Notes.RemoveAll(n => n.NoteName == NoteName.CSharp);
    }
}

notesManager.Notes does not exist.

error CS1061: 'TimedObjectsManager' does not contain a definition for 'Notes' and no accessible extension method 'Notes' accepting a first argument of type 'TimedObjectsManager' could be found (are you missing a using directive or an assembly reference?)

[melanchall]

Hi,

Thank you, I'll fix the example. You just need to use notesManager.Objects.

[Phibonacci]

Thanks for your quick answer.

I looked at the ManageNotes extension but then I get an IEnumerable that cannot be modified.

[melanchall]

I looked at the ManageNotes extension but then I get an IEnumerable that cannot be modified.

Where? What code? Please provide details.

[Phibonacci]

After going through the library I found a method to update the chords. I thought this would allow me to remove all notes from each chord but the first one, on all tracks.

using Melanchall.DryWetMidi.Core;
using Melanchall.DryWetMidi.Interaction;

var midiFile = MidiFile.Read("in.mid");
foreach (var trackChunk in midiFile.GetTrackChunks())
{
    trackChunk.ProcessChords(TrimChord);
}
midiFile.Write("out.mid");

void TrimChord(Chord chord)
{
    chord.Notes.RemoveAll(x => x != chord.Notes.First());
}

But the output file is identical to the input one.

I'm guessing the ProcessChords is making copies of the chords. How can I edit them instead?

[Phibonacci]

This worked.

using Melanchall.DryWetMidi.Core;
using Melanchall.DryWetMidi.Interaction;

var midiFile = MidiFile.Read("in.mid");
foreach (var trackChunk in midiFile.GetTrackChunks())
{
    var newChords = new List<Chord>();
    foreach (var chord in trackChunk.GetChords())
    {
        var higherNote = FindHigherNote(chord.Notes);
        chord.Notes.RemoveAll(x => x != higherNote);
        newChords.Add(chord);
    }
    trackChunk.RemoveChords();
    trackChunk.AddObjects(newChords);
}

Note? FindHigherNote(TimedObjectsCollection<Note> notes)
{
    var higherNote = notes.First();
    foreach (var note in notes)
    {
        if (higherNote.GetMusicTheoryNote().CompareTo(note.GetMusicTheoryNote()) < 0)
        {
            higherNote = note;
        }
    }
    return higherNote;
}

midiFile.Write("out.mid");

[melanchall]

I'm guessing the ProcessChords is making copies of the chords. How can I edit them instead?

That's correct. But the file should be updated. Hmm, it's probably a bug in the library. I'll check it. Please don't close the issue.

[melanchall]

Yes, that's the bug. I'll think how to support chord's notes collection changes within ProcessChords methods.

[melanchall]

I've released DryWetMIDI 7.0.0-prerelease2 which introduces ChordProcessingHint parameter in ProcessChords methods. So now for your task you can use this code:

midiFile.ProcessChords(
    chord => 
    {
        var higherNote = FindHigherNote(chord.Notes);
        chord.Notes.RemoveAll(x => x != higherNote);
    },
    hint: ChordProcessingHint.NotesCollectionCanBeChanged);

Thanks for the issue!

[melanchall]

🚀 7.0.0 version is released now!

Prerelease NuGet packages will be unlisted soon, so please update the package references to the new version.