/// <summary>
/// Sorts, removes empty tracks and adds end track markers
/// </summary>
public void PrepareForExport()
{
var comparer = new MidiEventComparer();
// 1. sort each track
foreach (List <MidiEvent> list in trackEvents)
{
MergeSort.Sort(list, comparer);
// 2. remove all End track events except one at the very end
int index = 0;
while (index < list.Count - 1)
{
if (MidiEvent.IsEndTrack(list[index]))
{
list.RemoveAt(index);
}
else
{
index++;
}
}
}
int track = 0;
// 3. remove empty tracks and add missing
while (track < trackEvents.Count)
{
IList <MidiEvent> list = trackEvents[track];
if (list.Count == 0)
{
RemoveTrack(track);
}
else
{
if (list.Count == 1 && MidiEvent.IsEndTrack(list[0]))
{
RemoveTrack(track);
}
else
{
if (!MidiEvent.IsEndTrack(list[list.Count - 1]))
{
list.Add(new MetaEvent(MetaEventType.EndTrack, 0, list[list.Count - 1].AbsoluteTime));
}
track++;
}
}
}
}
/// <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(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(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 (var 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;
}
}
}
