private void ReadHeader(BinaryReader reader)
{
if (BigEndianHelper.ReadInt32(reader) != 6) //midi header should be 6 bytes long
{
throw new Exception("Midi header is invalid.");
}
mTrackFormat = (TrackFormat)BigEndianHelper.ReadInt16(reader);
mTracks = new MidiTrack[BigEndianHelper.ReadInt16(reader)];
int div = BigEndianHelper.ReadInt16(reader);
mDivision = div & 0x7FFF;
mTimeFormat = ((div & 0x8000) > 0) ? TimeFormat.FamesPerSecond : TimeFormat.TicksPerBeat;
}
private static MidiTrack ReadTrack(BinaryReader reader)
{
List <byte> instList = new List <byte>();
List <byte> drumList = new List <byte>();
List <MidiEvent> eventList = new List <MidiEvent>();
int channelList = 0;
int noteOnCount = 0;
int totalTime = 0;
while (!new string(IOHelper.Read8BitChars(reader, 4)).Equals("MTrk"))
{
int length = BigEndianHelper.ReadInt32(reader);
while (length > 0)
{
length--;
reader.ReadByte();
}
}
long endPosition = BigEndianHelper.ReadInt32(reader) + reader.BaseStream.Position;
byte prevStatus = 0;
while (reader.BaseStream.Position < endPosition)
{
int delta = ReadVariableLength(reader);
totalTime += delta;
byte status = reader.ReadByte();
if (status >= 0x80 && status <= 0xEF)
{//voice message
prevStatus = status;
eventList.Add(ReadVoiceMessage(reader, delta, status, reader.ReadByte()));
TrackVoiceStats(eventList[eventList.Count - 1], instList, drumList, ref channelList, ref noteOnCount);
}
else if (status >= 0xF0 && status <= 0xF7)
{//system common message
prevStatus = 0;
eventList.Add(ReadSystemCommonMessage(reader, delta, status));
}
else if (status >= 0xF8 && status <= 0xFF)
{//realtime message
eventList.Add(ReadRealTimeMessage(reader, delta, status));
}
else
{ //data bytes
if (prevStatus == 0)
{ //if no running status continue to next status byte
while ((status & 0x80) != 0x80)
{
status = reader.ReadByte();
}
if (status >= 0x80 && status <= 0xEF)
{//voice message
prevStatus = status;
eventList.Add(ReadVoiceMessage(reader, delta, status, reader.ReadByte()));
TrackVoiceStats(eventList[eventList.Count - 1], instList, drumList, ref channelList, ref noteOnCount);
}
else if (status >= 0xF0 && status <= 0xF7)
{//system common message
eventList.Add(ReadSystemCommonMessage(reader, delta, status));
}
else if (status >= 0xF8 && status <= 0xFF)
{//realtime message
eventList.Add(ReadRealTimeMessage(reader, delta, status));
}
}
else
{//otherwise apply running status
eventList.Add(ReadVoiceMessage(reader, delta, prevStatus, status));
TrackVoiceStats(eventList[eventList.Count - 1], instList, drumList, ref channelList, ref noteOnCount);
}
}
}
if (reader.BaseStream.Position != endPosition)
{
throw new Exception("The track length was invalid for the current MTrk chunk.");
}
if (((channelList >> MidiHelper.DrumChannel) & 1) == 1)
{
if (!drumList.Contains(0))
{
drumList.Add(0);
}
}
else
{
if (!instList.Contains(0))
{
instList.Add(0);
}
}
MidiTrack track = new MidiTrack(instList.ToArray(), drumList.ToArray(), eventList.ToArray());
track.NoteOnCount = noteOnCount;
track.EndTime = totalTime;
track.ActiveChannels = channelList;
return(track);
}
