The class MidiFileWriter2, available with MPTK Pro V2.88 , is useful to create Midi file by script. It replaces the class MidiFileWriter which is deprecated. MidiFileWriter2 proposes a more consistent behavior with the others classes of MPTK and new helpful functions.

• Channel from 0 to 15
• Methods for all Midi events
• Better errors check

Also look at these page:  Midi Timing and Integration of MPTK by script.

There is two demonstrations scenes: TestMidiGenerator and TinyMidiSequencer. Begin with TestMidiGenerator, it’s very easy to understand.

The schema is classical and you will find all the detail for the class MidiFileWriter2 here in the documentation.

• Create a MidiFileWriter2.
• Create Tracks, minimum one. Since v2.88, tracks are created automatically.
• Add Midi Event (note, preset change, …). There is two groups of methods:
  • defined timing in millisecond: more easy to understand but initial tempo must be respected.
  • defined timing in ticks: independent of the tempo.
• Close each tracks. Since v2.88, tracks are close automatically
• Write the Midi file or Play the Midi file.

See below an extract of the demonstration script.

First example with timing defined in millisecond:

/// <summary>
/// Play four consecutive quarters from 60 (C5) to 63.
/// Use AddNoteMS method for Tempo and duration defined in milliseconds.
/// </summary>
/// <returns></returns>
private MidiFileWriter2 CreateMidiStream_1()
{
    // In this demo, we are using variable to contains tracks and channel values only for better understanding. 

    // Using multiple tracks is not mandatory,  you can arrange your song as you want.
    // But first track (index=0) is often use for general midi information track, lyrics, tempo change. By convention contains no noteon.
    int track0 = 0;

    // Second track (index=1) will contains the notes, preset change, .... all events associated to a channel.
    int track1 = 1;

    int channel0 = 0; // we are using only one channel in this demo

    // Create a Midi file of type 1 (recommended)
    MidiFileWriter2 mfw = new MidiFileWriter2();

    mfw.MPTK_AddText(track0, 0, MPTKMeta.Copyright, "Simple Midi Generated. 4 quarter at 120 BPM");

    // Playing tempo must be defined at start of the stream. 
    // Defined BPM is mandatory when duration and delay are defined in millisecond in the stream. 
    // The value of the BPM is used to transform duration from milliseconds to internal ticks value.
    // Obviously, duration in millisecànds depends on the BPM selected. With BPM=120, a quarter duration is 500 milliseconds.
    mfw.MPTK_AddBPMChange(track0, 0, 120);

    // Add four consecutive quarters from 60 (C5)  to 63.
    // With BPM=120, quarter duration is 500ms (60000 / 120). So, notes are played at, 0, 500, 1000, 1500 ms from the start.
    mfw.MPTK_AddNoteMilli(track1, 0f, channel0, 60, 50, 500f);
    mfw.MPTK_AddNoteMilli(track1, 500f, channel0, 61, 50, 500f);
    mfw.MPTK_AddNoteMilli(track1, 1000f, channel0, 62, 50, 500f);
    mfw.MPTK_AddNoteMilli(track1, 1500f, channel0, 63, 50, 500f);

    // Silent note : velocity=0 (will generate only a noteoff)
    mfw.MPTK_AddNoteMilli(track1, 3000f, channel0, 80, 0, 250f);

    return mfw;
}
Code language: C# (cs)

Second example with timing defined in ticks. The result is exactly the same that with the first example:

/// <summary>
/// Four consecutive quarters played independently of the tempo.
/// </summary>
/// <returns></returns>
private MidiFileWriter2 CreateMidiStream_2()
{
    // In this demo, we are using variable to contains tracks and channel values only for better understanding. 

    // Using multiple tracks is not mandatory,  you can arrange your song as you want.
    // But first track (index=0) is often use for general midi information track, lyrics, tempo change. By convention contains no noteon.
    int track0 = 0;

    // Second track (index=1) will contains the notes, preset change, .... all events associated to a channel.
    int track1 = 1;

    int channel0 = 0; // we are using only one channel in this demo

    long absoluteTime = 0;

    // Create a Midi file of type 1 (recommended)
    MidiFileWriter2 mfw = new MidiFileWriter2();

    mfw.MPTK_AddTimeSignature(0, 0, 4, 4);

    // 240 is the default. A classical value for a Midi. define the time precision.
    int ticksPerQuarterNote = mfw.MPTK_DeltaTicksPerQuarterNote;

    // Some textual information added to the track 0 at time=0
    mfw.MPTK_AddText(track0, 0, MPTKMeta.Copyright, "Simple Midi Generated. 4 quarter at 120 BPM");

    // Define Tempo is not mandatory when using time in ticks. The default 120 BPM will be used.
    //mfw.MPTK_AddBPMChange(track0, 0, 120);

    // Add four consecutive quarters from 60 (C5)  to 63.
    mfw.MPTK_AddNote(track1, absoluteTime, channel0, 60, 50, ticksPerQuarterNote);

    // Next note will be played one quarter after the previous
    absoluteTime += ticksPerQuarterNote;
    mfw.MPTK_AddNote(track1, absoluteTime, channel0, 61, 50, ticksPerQuarterNote);

    absoluteTime += ticksPerQuarterNote;
    mfw.MPTK_AddNote(track1, absoluteTime, channel0, 62, 50, ticksPerQuarterNote);

    absoluteTime += ticksPerQuarterNote;
    mfw.MPTK_AddNote(track1, absoluteTime, channel0, 63, 50, ticksPerQuarterNote);

    // Silent note : velocity=0 (will generate only a noteoff)
    absoluteTime += ticksPerQuarterNote * 2;
    mfw.MPTK_AddNote(track1, absoluteTime, channel0, 80, 0, ticksPerQuarterNote);

    return mfw;
}

Code language: C# (cs)

Now play directly the Midi list of events. All the methods available for playing a Midi file with MidiFilePlayer are also available. For example: defined callback at start, end of Midi, at each notes, looping, …

private void PlayDirectlyMidiSequence(string name, MidiFileWriter2 mfw)
{
    // Play midi with the MidiExternalPlay prefab without saving midi in a file
    MidiFilePlayer midiPlayer = FindObjectOfType<MidiFilePlayer>();

    midiPlayer.MPTK_Stop();
    mfw.MPTK_MidiName = name;

    midiPlayer.OnEventStartPlayMidi.RemoveAllListeners();
    midiPlayer.OnEventStartPlayMidi.AddListener((string midiname) =>
    {
        startPlaying = DateTime.Now;
        Debug.Log($"Start playing {midiname} at {startPlaying}");
    });

    midiPlayer.OnEventEndPlayMidi.RemoveAllListeners();
    midiPlayer.OnEventEndPlayMidi.AddListener((string midiname, EventEndMidiEnum reason) =>
    {
        Debug.Log($"End playing {midiname} {reason} Duration={(DateTime.Now - startPlaying).TotalSeconds:F3}");
    });

    midiPlayer.OnEventNotesMidi.RemoveAllListeners();
    midiPlayer.OnEventNotesMidi.AddListener((List<MPTKEvent> events) =>
    {
        foreach (MPTKEvent midievent in events)
            Debug.Log($"At {midievent.RealTime:F1} ms play: {midievent.ToString()}");
    });


    midiPlayer.MPTK_Loop = true;

    // Sort the events by ascending absolute time (optional)
    mfw.MPTK_SortEvents();
    mfw.MPTK_Debug();

    // Send the midi sequence to internal midi sequencer
    midiPlayer.MPTK_Play(mfw);
}
Code language: C# (cs)

Or write it to a Midi file:

private void WriteMidiSequenceToFile(string name, MidiFileWriter2 mfw)
{
    // build the path + filename to the midi
    string filename = Path.Combine(Application.persistentDataPath, name + ".mid");
    Debug.Log("Write Midi file:" + filename);

    // Sort the events by ascending absolute time (optional)
    mfw.MPTK_SortEvents();
    mfw.MPTK_Debug();

    // Write the midi file
    mfw.MPTK_WriteToFile(filename);
}
Code language: C# (cs)