public static void Parse(Model midi, string filename, int frameRateMillis = 50)
{
using (MidiBigEndianWriter writer = new MidiBigEndianWriter(File.Open(filename, FileMode.Create)))
{
ParseHeaderChunk(writer, frameRateMillis);
ParseTrackChunk(midi, writer, frameRateMillis);
}
}
private static void ParseTrackChunk(Model midi, MidiBigEndianWriter writer, int frameRateMillis)
{
// track chunk signature
writer.Write((uint)0x4D54726B);
var notes = midi.Where((MidiControlEvent e) => e is NoteOn || e is NoteOff).OrderBy(e => e.AbsoluteRealTime).ToArray();
// notes + instrument + end of track
var length = notes.Length * 7 + 6 * (Instrument.NumberOfClusters - 1) + 4;
// write the length of the track
writer.Write((uint)length);
// write instrument changes
for (var i = 0; i < Instrument.NumberOfClusters; i++)
{
if (i == Channel.PercussionChannelNumber)
{
continue;
}
writer.WriteSemiVariableLengthValue(0);
writer.Write((byte)(0xC0 | i));
writer.Write((byte)Instrument.TypicalInstrument((InstrumentCluster)i).Id());
}
var lastTime = 0.0;
foreach (var note in notes)
{
// delta time
writer.WriteSemiVariableLengthValue((uint)((note.AbsoluteRealTime.TotalMilliseconds - lastTime)));
if (note is NoteOn)
{
var noteOn = (NoteOn)note;
// event type
writer.Write((byte)(0x90 | note.ChannelNumber));
writer.Write((byte)noteOn.NoteNumber);
writer.Write((byte)noteOn.Volume);
}
else if (note is NoteOff)
{
var noteOff = (NoteOff)note;
// event type
writer.Write((byte)(0x80 | note.ChannelNumber));
writer.Write((byte)noteOff.NoteNumber);
writer.Write((byte)noteOff.Velocity);
}
lastTime = note.AbsoluteRealTime.TotalMilliseconds;
}
// end of track
// delta time
writer.WriteVariableLengthValue(0);
// meta event
writer.Write((byte)0xFF);
// end of track event
writer.Write((byte)0x2F);
// length
writer.WriteVariableLengthValue(0);
}
