/**
* Write a track to an output stream.
*
* @param track the track to write
* @param dos a MidiDataOutputStream to write to
* @return the number of bytes written
*/
private int writeTrack(Track track, MidiDataOutputStream dos) throws IOException {
int i = 0, elength = track.size(), trackLength;
MidiEvent pme = null;
dos.writeInt(0x4d54726b); // "MTrk"
trackLength = computeTrackLength(track, dos);
dos.writeInt(trackLength);
while (i < elength) {
MidiEvent me = track.get(i);
int dtime = 0;
if (pme != null) dtime = (int) (me.getTick() - pme.getTick());
dos.writeVariableLengthInt(dtime);
// FIXME: use running status byte
byte msg[] = me.getMessage().getMessage();
dos.write(msg);
pme = me;
i++;
}
// We're done if the last event was an End of Track meta message.
if (pme != null && (pme.getMessage() instanceof MetaMessage)) {
MetaMessage mm = (MetaMessage) pme.getMessage();
if (mm.getType() == 0x2f) // End of Track message
return trackLength + 8;
}
// Write End of Track meta message
dos.writeVariableLengthInt(0); // Delta time of 0
dos.writeByte(0xff); // Meta Message
dos.writeByte(0x2f); // End of Track message
dos.writeVariableLengthInt(0); // Length of 0
return trackLength + 8 + 4;
}
/**
* Compute the length of a track as it will be written to the output stream.
*
* @param track the track to measure
* @param dos a MidiDataOutputStream used for helper method
* @return the length of the track
*/
private int computeTrackLength(Track track, MidiDataOutputStream dos) {
int count = 0, length = 0, i = 0, eventCount = track.size();
long ptick = 0;
while (i < eventCount) {
MidiEvent me = track.get(i);
long tick = me.getTick();
length += dos.variableLengthIntLength((int) (tick - ptick));
ptick = tick;
length += me.getMessage().getLength();
i++;
}
return length;
}
/* Write a sequence to an output stream in standard midi format.
* @see javax.sound.midi.spi.MidiFileWriter#write(javax.sound.midi.Sequence, int, java.io.OutputStream)
*/
public int write(Sequence in, int fileType, OutputStream out) throws IOException {
MidiDataOutputStream dos = new MidiDataOutputStream(out);
Track[] tracks = in.getTracks();
dos.writeInt(0x4d546864); // MThd
dos.writeInt(6);
dos.writeShort(fileType);
dos.writeShort(tracks.length);
float divisionType = in.getDivisionType();
int resolution = in.getResolution();
// FIXME: division computation is incomplete.
int division = 0;
if (divisionType == Sequence.PPQ) division = resolution & 0x7fff;
dos.writeShort(division);
int length = 14;
for (Track track : tracks) length += writeTrack(track, dos);
return length;
}