/// <summary>
/// Exports a MIDI file
/// </summary>
/// <param name="filename">Filename to export to</param>
/// <param name="events">Events to export</param>
public static void Export(string filename, MidiEventCollection events)
{
if (events.MidiFileType == 0 && events.Tracks > 1)
{
throw new ArgumentException("Can't export more than one track to a type 0 file");
}
using (var writer = new BinaryWriter(File.Create(filename)))
{
writer.Write(Encoding.UTF8.GetBytes("MThd"));
writer.Write(SwapUInt32((uint)6)); // chunk size
writer.Write(SwapUInt16((ushort)events.MidiFileType));
writer.Write(SwapUInt16((ushort)events.Tracks));
writer.Write(SwapUInt16((ushort)events.DeltaTicksPerQuarterNote));
for (int track = 0; track < events.Tracks; track++)
{
IList <MidiEvent> eventList = events[track];
writer.Write(Encoding.UTF8.GetBytes("MTrk"));
long trackSizePosition = writer.BaseStream.Position;
writer.Write(SwapUInt32((uint)0));
long absoluteTime = events.StartAbsoluteTime;
// use a stable sort to preserve ordering of MIDI events whose
// absolute times are the same
MergeSort.Sort(eventList, new MidiEventComparer());
if (eventList.Count > 0)
{
System.Diagnostics.Debug.Assert(MidiEvent.IsEndTrack(eventList[eventList.Count - 1]), "Exporting a track with a missing end track");
}
foreach (MidiEvent midiEvent in eventList)
{
midiEvent.Export(ref absoluteTime, writer);
}
uint trackChunkLength = (uint)(writer.BaseStream.Position - trackSizePosition) - 4;
writer.BaseStream.Position = trackSizePosition;
writer.Write(SwapUInt32(trackChunkLength));
writer.BaseStream.Position += trackChunkLength;
}
}
}
/// <summary>
/// Opens a MIDI file for reading
/// </summary>
/// <param name="filename">Name of MIDI file</param>
/// <param name="strictChecking">If true will error on non-paired note events</param>
public MidiFile(string filename, bool strictChecking)
{
this.strictChecking = strictChecking;
var br = new BinaryReader(File.OpenRead(filename));
using (br)
{
string chunkHeader = Encoding.UTF8.GetString(br.ReadBytes(4));
if (chunkHeader != "MThd")
{
throw new FormatException("Not a MIDI file - header chunk missing");
}
uint chunkSize = SwapUInt32(br.ReadUInt32());
if (chunkSize != 6)
{
throw new FormatException("Unexpected header chunk length");
}
// 0 = single track, 1 = multi-track synchronous, 2 = multi-track asynchronous
fileFormat = SwapUInt16(br.ReadUInt16());
int tracks = SwapUInt16(br.ReadUInt16());
deltaTicksPerQuarterNote = SwapUInt16(br.ReadUInt16());
events = new MidiEventCollection((fileFormat == 0)?0:1, deltaTicksPerQuarterNote);
for (int n = 0; n < tracks; n++)
{
events.AddTrack();
}
long absoluteTime = 0;
for (int track = 0; track < tracks; track++)
{
if (fileFormat == 1)
{
absoluteTime = 0;
}
chunkHeader = Encoding.UTF8.GetString(br.ReadBytes(4));
if (chunkHeader != "MTrk")
{
throw new FormatException("Invalid chunk header");
}
chunkSize = SwapUInt32(br.ReadUInt32());
long startPos = br.BaseStream.Position;
MidiEvent me = null;
var outstandingNoteOns = new List <NoteOnEvent>();
while (br.BaseStream.Position < startPos + chunkSize)
{
me = MidiEvent.ReadNextEvent(br, me);
absoluteTime += me.DeltaTime;
me.AbsoluteTime = absoluteTime;
events[track].Add(me);
if (me.CommandCode == MidiCommandCode.NoteOn)
{
NoteEvent ne = (NoteEvent)me;
if (ne.Velocity > 0)
{
outstandingNoteOns.Add((NoteOnEvent)ne);
}
else
{
// don't remove the note offs, even though
// they are annoying
// events[track].Remove(me);
FindNoteOn(ne, outstandingNoteOns);
}
}
else if (me.CommandCode == MidiCommandCode.NoteOff)
{
FindNoteOn((NoteEvent)me, outstandingNoteOns);
}
else if (me.CommandCode == MidiCommandCode.MetaEvent)
{
MetaEvent metaEvent = (MetaEvent)me;
if (metaEvent.MetaEventType == MetaEventType.EndTrack)
{
//break;
// some dodgy MIDI files have an event after end track
if (strictChecking)
{
if (br.BaseStream.Position < startPos + chunkSize)
{
throw new FormatException(String.Format("End Track event was not the last MIDI event on track {0}", track));
}
}
}
}
}
if (outstandingNoteOns.Count > 0)
{
if (strictChecking)
{
throw new FormatException(String.Format("Note ons without note offs {0} (file format {1})", outstandingNoteOns.Count, fileFormat));
}
}
if (br.BaseStream.Position != startPos + chunkSize)
{
throw new FormatException(String.Format("Read too far {0}+{1}!={2}", chunkSize, startPos, br.BaseStream.Position));
}
}
}
}