public static MidiFileAsset Load(byte [] data)
{
var reader = new MidiDataStreamReader(data);
// Chunk type
if (reader.ReadChars(4) != "MThd")
{
throw new FormatException("Can't find header chunk.");
}
// Chunk length
if (reader.ReadBEUInt32() != 6u)
{
throw new FormatException("Length of header chunk must be 6.");
}
// Format (unused)
reader.Advance(2);
// Number of tracks
var trackCount = reader.ReadBEUInt16();
// Ticks per quarter note
var tpqn = reader.ReadBEUInt16();
if ((tpqn & 0x8000u) != 0)
{
throw new FormatException("SMPTE time code is not supported.");
}
// Tracks
var tracks = new MidiAnimationAsset [trackCount];
for (var i = 0; i < trackCount; i++)
{
tracks[i] = ReadTrack(reader, tpqn);
}
// Asset instantiation
var asset = ScriptableObject.CreateInstance <MidiFileAsset>();
asset.tracks = tracks;
return(asset);
}
static MidiAnimationAsset ReadTrack(MidiDataStreamReader reader, uint tpqn)
{
// Chunk type
if (reader.ReadChars(4) != "MTrk")
{
throw new FormatException("Can't find track chunk.");
}
// Chunk length
var chunkEnd = reader.ReadBEUInt32();
chunkEnd += reader.Position;
// MIDI event sequence
var events = new List <MidiEvent>();
var ticks = 0u;
var stat = (byte)0;
while (reader.Position < chunkEnd)
{
// Delta time
ticks += reader.ReadMultiByteValue();
// Status byte
if ((reader.PeekByte() & 0x80u) != 0)
{
stat = reader.ReadByte();
}
if (stat == 0xffu)
{
// 0xff: Meta event (unused)
reader.Advance(1);
reader.Advance(reader.ReadMultiByteValue());
}
else if (stat == 0xf0u)
{
// 0xf0: SysEx (unused)
while (reader.ReadByte() != 0xf7u)
{
}
}
else
{
// MIDI event
var b1 = reader.ReadByte();
var b2 = (stat & 0xe0u) == 0xc0u ? (byte)0 : reader.ReadByte();
events.Add(new MidiEvent {
time = ticks, status = stat, data1 = b1, data2 = b2
});
}
}
// Quantize duration with bars.
var bars = (ticks + tpqn * 4 - 1) / (tpqn * 4);
// Asset instantiation
var asset = ScriptableObject.CreateInstance <MidiAnimationAsset>();
asset.template.tempo = 120;
asset.template.duration = bars * tpqn * 4;
asset.template.ticksPerQuarterNote = tpqn;
asset.template.events = events.ToArray();
return(asset);
}
