//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)
{
}
}
}
//read data for a single event in a track's data, convert the event's delta time to an absolute track time
private static Event loadEventData(MidiInStream stream)
{
Event evt = null;
int status = stream.getOne();
if (status < 0x80) //running status
{
stream.pushBack(1);
status = runningStatus;
}
if (status >= 0x80 && status < 0xff) //message event
{
Message msg = loadMessageData(stream, status);
runningStatus = status;
evt = new MessageEvent(msg);
}
else if (status == 0xff) //meta event
{
evt = loadMetaEventData(stream); //this may return null for unrecognized events
}
else
{
throw new MidiFileException(stream.filename + " has an invalid event at", stream.getDataPos() - 8);
}
return(evt);
}