//- loading -------------------------------------------------------------------
//read in a midi seqence from a standard midi file
public static Sequence readMidiFile(String filename)
{
MidiInStream stream = new MidiInStream(filename);
//read midi file header
String sig = stream.getString(4);
uint hdrsize = stream.getFour();
int fileFormat = stream.getTwo();
int trackCount = stream.getTwo();
int division = stream.getTwo();
if (!sig.Equals("MThd") || hdrsize != 6)
{
throw new MidiFileException(filename + " is not a valid MIDI file ", 0);
}
Sequence seq = new Sequence(division);
loadTrackZeroData(stream, seq);
//read midi track data
for (int trackNum = 1; trackNum < trackCount; trackNum++)
{
curTrackNum = trackNum;
loadTrackData(stream, seq, trackNum);
}
finalizeTracks(seq);
return(seq);
}
//read data from a single track chunk
private static void loadTrackData(MidiInStream stream, Sequence seq, int trackNum)
{
//read track header
String trackSig = stream.getString(4);
uint trackDataLength = stream.getFour();
if (!trackSig.Equals("MTrk"))
{
throw new MidiFileException(stream.filename + " has an invalid track at ", stream.getDataPos() - 8);
}
Track track = seq.addTrack(); //get new track from sequence
track.setName("Track " + trackNum.ToString());
int currentTime = 0; //event time in ticks
runningStatus = 0;
sysexCont = false;
prevSysEx = null;
Event evt = null;
int startpos = stream.getDataPos();
while ((stream.getDataPos() - startpos) < trackDataLength)
{
currentTime += (int)stream.getVariableLengthVal(); //add delta time to current num of ticks
evt = loadEventData(stream);
if ((evt != null) && !(evt is EndofTrackEvent ||
evt is MarkerEvent || evt is CuePointEvent || //these are ignored in tracks other than track 0
evt is TempoEvent || evt is SMPTEOffsetEvent ||
evt is TimeSignatureEvent || evt is KeySignatureEvent))
{
track.addEvent(evt, currentTime);
}
}
//last event in track must be an "end of track" event
if ((evt != null) && !(evt is EndofTrackEvent))
{
throw new MidiFileException(stream.filename + ": track " + curTrackNum.ToString() +
"missing end of track event at ", stream.getDataPos() - 8);
}
}
//build the tempo, meter and marker maps from tempo message from track 0
private static void loadTrackZeroData(MidiInStream stream, Sequence seq)
{
//read track header
String trackSig = stream.getString(4);
uint trackDataLength = stream.getFour();
if (!trackSig.Equals("MTrk"))
{
throw new MidiFileException(stream.filename + " has an invalid track 0 at ", stream.getDataPos() - 8);
}
int currentTime = 0; //event time in ticks
runningStatus = 0;
sysexCont = false;
prevSysEx = null;
Event evt;
Meter prevMeter = null;
int startpos = stream.getDataPos();
while ((stream.getDataPos() - startpos) < trackDataLength)
{
currentTime += (int)stream.getVariableLengthVal(); //add delta time to current num of ticks
evt = loadEventData(stream);
if (evt is TempoEvent)
{
Tempo tempo = new Tempo(currentTime, ((TempoEvent)evt).tempo);
seq.tempoMap.addTempo(tempo);
}
else if (evt is SMPTEOffsetEvent) //not handling smpte timing yet
{
}
else if (evt is TimeSignatureEvent)
{
int keysig = (prevMeter != null) ? prevMeter.keysig : 0;
Meter meter = new Meter(currentTime, ((TimeSignatureEvent)evt).numer, ((TimeSignatureEvent)evt).denom, keysig);
seq.meterMap.addMeter(meter);
prevMeter = meter;
}
else if (evt is KeySignatureEvent)
{
int numer = 4;
int denom = 4;
if (prevMeter != null)
{
numer = prevMeter.numer;
denom = prevMeter.denom;
}
Meter meter = new Meter(currentTime, numer, denom, ((KeySignatureEvent)evt).keySig);
seq.meterMap.addMeter(meter);
prevMeter = meter;
}
else if (evt is MarkerEvent)
{
}
else if (evt is CuePointEvent)
{
}
}
}
